Paul G

Active member
I'll just drop this here and we'll see what comes of it.

pH 6.6 typical
ORP 340 - 390 mv typical
CONDUCTIVITY 750 uS/cm typical
OXYGEN 6 - 10 ppm
CO2 50 ppm typical
GH 110 ppm typical
CALCIUM 75 ppm typical
MAGNESIUM 30 ppm typical
Ca:Mg 2.5 : 1
KH 120 ppm typical
IRON, total 0.30 ppm typical
NO3 5 - 10 ppm typical
PO4 3 - 5 ppm typical
POTASSIUM 40 - 50 ppm typical
SO4 > 200 ppm

Source Water : RO / DI
Total Filtration Turnover : 1200 GPH minimum
Substrate : inert siliceous gravel w/ high CEC calcined clay and granulated laterite
Chemical Filtration : no carbon or resins of any kind are used
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Paul G

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Echinodorus 'ozelot' (six individuals)
Nymphaea lotus, rubra
Anubias barteri
Anubias gracilis
Cryptocoryne wendtii
Hygrophila difformis
Ludwigia repens
Sagittaria subulata
Hydrocotyle luecocephala

I regard the swords and the nymphaea to be the keystones of the ecosystem. The occurrence of any kind of algae is inversely proportional to the productivity of these large plants. There is currently no nuisance algae in this tank. Some green spot and a little bba were evident up to about a year ago, but died back when the big plants settled in and started sending out leaves. Large leaves are regularly removed to let in the light. I try to limit floating leaves of the nymphaea to five or six; new leaves get very large very quickly.

In near future I will be putting in some Java fern, Microsorum pteropus, if I can find some really healthy robust pieces.

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Paul G

Active member
I use Neptune Systems Apex Aquacontroller to manage this aquarium. As many functions as lend themselves to it are automated. Here is the dosing system. There is a lot of DYI going on here. I will be happy to share details if there is further interest.

Each additive/supplement is contained in a dedicated 1.5 liter vat (small AquaMaxx). The concentration of each is consistently maintained while the dose rate is determined by the run-time of the peristaltic pumps (Milwaukee). The doses are regulated by Apex timer programs. Dosing is daily. All feeds are done at 06:00, except PO4 which is done at 18:00 to minimize trace removal by precipitation of insolubles. UV is turned off from 06:00 to 12:00 to prevent premature chelate denaturation. The additives are

KH BOOST (Sodium Bicarbonate)
GH BOOST (Sulfates of Calcium, Magnesium, and Potassium)
ORGANICS (50:50 mix SeaChem EXCEL and ADVANCE)
N : 0 : K (Potassium Nitrate, no Phosphorus)
0 : P : K (Monopotassium Phosphate, no Nitrogen)
(The eighth outlet is an unused spare.)

The dosing rates (run times) are determined over time, depending entirely on the apparent health and productivity of the plants. I test everything frequently. If something looks like it's running behind or ahead of demand, I can easily adjust the daily dose by changing the timer (one program line in the Aquacontroller). This routine is inherently adaptable to the exact tank conditions, types of plants, biomass, etc. It requires some methodical experimentation, but in the long run it eliminates a lot of guesswork.
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Paul G

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The pumps are Iwaki MD55-RLT. All loops are closed recirculating high-pressure siphon feed. There is no net head loss for lift. All losses occur in the piping and apparatus. Conduit is 1" ID with few exceptions. The nominal flow rate in each high speed loop is 450 gph, varying with condition of filters of course. Note that water in these loops is transferred to opposite sides of the tank for maximum mixing. The processing loops run about 170 to 210 gph, depending on the condition of the filters, with the loop having the chiller typically being the slower of the two. The chiller was necessary because of heat from the lights, due to the use of a closed canopy. More about this later.

The returns are spray bars below the waterline. They are rotatable so the flow may be directed. These are adjusted to affect 'RIPPLE' not 'CHOP' at the surface.

I use LifeGard QL UV-C sterilizers, a 40 watt and two 15 watt units. I like the QL types for ease of maintenance. My opinion here is that the fish are protected better from incidental infections than without UV, but I must remember to shut it down when dosing bacteria.

The water is polished to 25 microns. One such filter in each processing loop is adequate to maintain this polish. The high speed loops filter to 100 microns and keep the mix uniform.

The biological filtration in this system is robust. The plants are being forced to use nitrate exclusively, as ammonia is removed instantaneously. I provide them sufficient energy for this. The Matrix (SeaChem) is bagged, and is rinsed with every filter change. The bioballs (Coralife) do not have near the surface area of the Matrix, but they have "open" structure, so do not clog and resist channeling. They are not bagged. I only open these canisters once every couple of years just to check the smell. They are never anaerobic - ever. They are now nine years old.
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Paul G

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Pictured above is from this morning before I took the shears to it. The scape was looking pretty dark. I have let too many nymphaea leaves go unclipped. Quite a lot of overspreading tops in the Hygrophila and Ludwigia as well. I decided to prune just enough to let some light in. Some maintenance is scheduled for next week and I will get more aggressive then.

Ludwigia is an attractive red plant and hardy. It's fast growing. I've got it bushing out at the top and spreading out at the surface. I think this is pretty much how it likes to get its light and is a normal growth habit. It is pleasing to look at the dense growth from above, but it casts a lot of shade. It has a nice effect as a background plant because it is a good "filler," and I like it with the Echinodorus. I've been keeping Ludwigia for several years. It is eventually necessary when it is time to refresh the scape to allow the Ludwigia to overgrow in order to harvest leafy stems of good length for replanting, and pull out the old weak stumps. One downside to this plant is that it sheds leaves more readily than I'd like. But I appreciate its appearance in my scapes and I'll go on keeping it.

I scraped the front glass this AM. Way past due as you could see the Garra's mouthprints in the aufwuchs. While that is kind of interesting, it's a reminder that this needs doing every three days or so.

Tests today show that the iron is gradually falling off. The plants are devouring the stuff. This AM iron was 0.07 ppm, so I ran the Fe GLUCONATE doser for a full minute, then revised the daily dosing from 30 seconds to 40 seconds for both Fe GLUCONATE and MICRO/TRACE.

PO4 is doing okay, but I'll be watching the NO3. If NO3 falls below 5 ppm, I'll bump it up too.
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Paul G

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My personal preference for the overall appearance of the aquarium is to fully contain the light, to have a "viewscreen" aspect. There is a lot of energy being given off under this canopy and the heat does build up quickly. The air temperature above the water surface during daylight soon reaches 89 F, perfectly representing the tropical condition. Note the temperature probe. Above 89 F, the Apex is programmed to run six 5" fans installed on top of the canopy. The chiller is needed to pull down the water temp by only a couple of degrees. It does not run long or often, but without it the temp could creep up to higher than 80 F, especially in summer. I keep the aquarium water at 77 F.

The system diagram pretty much explains the lighting arrangement. The three Build My LED (BML) are 6300K high output, purpose built for dutch tanks. The 24V 60" strips are each comprised of five 12" Ecoxotic Stunners, all fitted with reflectors. The 24V and 12V power supplies are Automation Direct Rhino.

The turn-on schedule is TWILIGHT > DAWN A > DAWN B > SUN 1 > SUN 2 > SUN 3 > SUN 4. The turn-off schedule is SUN 4 > SUN 3 > SUN 2 > SUN 1 > DUSK B > DUSK A > TWILIGHT. All phases except SUN 4 are ramped brightness, up on turn-on and down on turn-off. The current programming has DAWN starting at 7:15 and DUSK full off at 22:00, and SUN 4 full on at 10:30 and full off at 18:30. The BLMs are presently set for 60% of maximum brightness and 30 minute ramp slopes. These are user programmed as 'profiles' in Apex. The ramp slopes of the Current USA timers are factory fixed at 15 minutes.

The BLMs are approximately 7" above the waterline, while the Stunners are at 8".
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Paul G

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This AM doing maintenance, testing, and pruning. These are the intakes, three just removed and their replacements. The dirty ones show what to expect in a planted tank. There is a constant evolution of detritus and it will clog the holes as it gradually decomposes in place. The flow meters show a reduction. When I did this today, the fast loop rates were almost at 400 gph, but returned to 480 gph. The processor loops recovered about 10 gph, but their rates are below normal, which means the 25 micron filters are due for replacement.

Loose muck is rinsed off the dirty intakes, then they are stored in straight bleach. When they come out they are rinsed thoroughly and go back into service. The rotation cycle is typically around three weeks. It does take about two weeks in undiluted bleach to completely clear the holes. There is no brushing involved, as it's not very effective at clearing the holes. The clean intakes do not go back into the tank until there is no hint of bleach smell on them.

These are 1" pvc pipe with 1/4" holes drilled in them. The mesh covering is standard fiberglass insect screen, wound tight and cemented with aquarium grade silicone adhesive caulk.

The bleach is reused. The bottles are 2" pvc pipe long enough to fully submerge the intake. After a few rotations, the bleach tends to neutralize. When it looses its strong smell, I replace it with new. This method economizes on bleach and the bottles can be capped and stowed out of the way.


Paul G

Active member
Yesterday morning I ran the iron doser for one minute and shut down the UV. After today's dosing, the iron is 0.56 ppm. This is about twice the normal target concentration. The iron test kit is Hanna H1721 Checker. This is an easy way to get really accurate results.

Nitrate is not keeping up despite recent increases, so it will get boosted again. I have set the doser for one minute a day.

Phosphate is holding at approximately 3 ppm according to both Fluval and Salifert test kits.

Potassium is holding at over 50 ppm. This is a LaMotte turbidity-based test. I have confidence that it is accurate within + or - 5 ppm, which is plenty good for my purposes.

KH is 6 degrees, not much changed from last test. A small amount of sodium bicarbonate is dosed daily. Normal acidification is being adequately buffered.

GH is 7 degrees. Again, no change. A dose of booster is done daily as the plants of course uptake magnesium and calcium.

These hardness tests, reported in degrees, are API test kits which I trust to give reasonably accurate results and are fast and easy to do. I can pin these parameters down to actual ppm numbers with LaMotte titration kits. I use the titration kits often enough to detect drift in the parameters, but I rely on the API kits for routine ball-parking.
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Paul G

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I have been experimenting here with iron ferts. In the following I make reference to claims made by SeaChem. To verify my citations go to the Discussions section of their website and surf around in the Sunken Gardens forum. Not all the info available from SeaChem is printed on the bottle.

As previously noted, I turned off the UV Wednesday AM, and as of Thursday AM I had brought up the iron to 0.56 ppm. No iron ferts were added until this AM. Everything else was done regularly and the plants spent those two days under the normal light cycle. I tested several times throughout the day Thursday and Friday. Friday evening the iron tested at 0.52 ppm. No change. The UV was turned back on at that time and ran all night until its regularly scheduled 6:00 AM shutoff. Then I allowed the normal dose of MICRO/TRACE which contains Ferric EDTA, but withheld the Ferrous Gluconate. I tested 4 hours later, after the lighting was well under way, and the iron was back down to 0.07 ppm.

SeaChem asserts, and I accept, that Flourish Iron is the superior iron fertilizer for foliar uptake because it is a carbohydrate that plants can metabolize readily, thereby being a good carbon source as well as having the advantage of releasing iron in the ferrous state. Something I have noticed since I continuously monitor ORP (redox), is that the ORP drops a full 100 mV every morning at dosing time (6:00 AM). The moment the gluconate goes into the water, the redox drops like a rock, then gradually rises to its normal "real" value by midday. Both days the gluconate was withheld, the redox did not fall off and has stabilized at about 380 mV on a flat curve. The ORP meter is keeping tabs on the relative abundances of reducing agents and oxidizing agents. In a system that is highly oxidative as a rule (in which plants produce lots of O2 and keep the dissolved oxygen at a high level day after day) a reduction in the redox can be interpreted as an increase in DOC, which is comprised largely of reducing agents. Gluconate is a dissolved carbohydrate and is a reducing agent. No other additive used, including Excel (gluteraldehyde), affects the redox in this way.

SeaChem asserts that the plants will consume a prescribed dose of Fe Gluconate so rapidly that it will virtually disappear from the system in half an hour. Of course, I think this depends on some variables such as rates and patterns of water circulation, and, as I assume the plants must be photosynthesizing and metabolizing normally for this to occur, the total plant mass, character of the light, and other things. In any case, I accept that the plants will uptake Fe Gluconate rapidly and I fully expect it to be consumed within a couple of hours in my system. SeaChem states that if you test 0.1 ppm iron within one half hour of dosing Flourish Iron, that is a sufficient dose of iron for the aquarium. This may be a better way of stating the case. But I should think that a heavily planted tank with highly productive specimens could do with a somewhat larger dose than that.

For cations to be bioavailable, they can be complexed with relatively stable organic molecules to preserve them, at least for a while, from being immediately bound to anions in the solution and present them to the plant as food it recognizes and can use. Both EDTA and gluconate are subject to photodissociation. Probably a UV sterilizer is a more expeditious way to get that done than is overhead visible light, but both will do. The gluconate ligand is probably fairly weak, which is a desirable characteristic in a plant fertilizer, as the idea is to require as little energy input from the plant as possible in order to get the iron ion out. Also the gluconate is a carbon source, and is likely a source, rather than a sink, of energy. EDTA is a hexadentate chelate and is a strong ligand. The plant has to pry the iron loose and then reduce it to ferrous state before it can use it. This requires energy from the plant. Many of the desirable metals in micronutrient fertilizer are made bioavailable by EDTA, or similar, chelation. Probably all such complexes can be decomposed by exposure to light. Some ligands are stronger than others, and rates of decomposition may be intensity and wavelength dependent. When these substances are exposed to light, the molecule is denatured and oxidizing agents and orthophosphate anions grab the metal, forming insoluble inorganics that precipitate out of solution and are no longer bioavailable, at least in terms of foliar uptake.

SeaChem says that you should not keep iron and phosphate ferts in the same bottle. Since Flourish iron is consumed so rapidly, there is little opportunity for it to decompose in the water column, so there isn't much concern about the timing of phosphate dosing. I think that does follow from the theory of what gluconate is and how it works, but I still dose these two nutrients 12 hours apart. It's just good karma. I also suspend UV exposure from 06:00 to 12:00 every day to maximize the gluconate's presence; that is, I give it 6 hours - 4 hours with lights on - before I subject it to UV.

Pretty clearly, the UV denatures EDTA fairly rapidly, as this experiment shows. And since EDTA complexed nutrients are not rapidly consumed, there may be a lot lost to UV exposure. This, I think, must be accepted and dealt with in much the same way as the inevitable loss due to water changes, especially by those who practice EI for example. It seems to me that many (most?) micro/trace nutrients are more ideally dosed via substrate, for root uptake. Getting this stuff into the roots from the water column is the hard way for the plant, but the easy way for the aquarist. I should probably make better use of root tabs, but in a large densely planted tank there are practical difficulties, and I wouldn't rely on that method completely in any case.

I will not be going to an "active" (soil-based) substrate. I like my inert gravel and unchanging Flourite mix. It is eternally stable.

All this explains also why I do not routinely use activated carbon. It is good at removing DOCs from water, and it won't remove desirable dissolved inorganics such as those that comprise macronutrients. But it will remove organic molecules, and that includes all ligands and the metals bound to them. Activated carbon is a good way to defeat dosing of anything that is complexed, and it will also take out gluteraldehyde (Excel), phytohormones, humic (blackwater) additives, and any allelopathic toxins the plants may be generating to suppress algae (and yes, I do believe in that). And the same goes for other chemical filtration media designed to latch onto organic molecules. I don't use them, and haven't missed them since I stopped.

So, there is no doubt in my mind that ferrous gluconate is the preferred way to provide iron to the aquatic macrophyte, provided certain things are borne in mind about when and how much to dose it. It does, however, play merry hell with my data curves.
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Paul G

Active member
This diagram is of the pressurized CO2 setup I am using. I purchase CO2 in 20 pound bottles. The in-line diffusor appears in a previous photo.

I use the Apex Aquacontroller for pH monitoring and control. The CO2 PRIMARY is programmed to maintain the average pH at 6.6, while the CO2 BACKUP is programmed to maintain pH at 6.8. When the primary empties, the pH will rise just enough to activate the backup. I replace the primary tank as soon as I notice it is empty, but the backup prevents the system pH from going out of control if I don't see it even for a few days (it could go to as high as around 8 I think).

The primary's solenoid valve is parallel connected to an elapsed time indicator. At present, one 20 pounder is good for over 150 hours and this lasts typically about a month or so. I will in future be paying closer attention to this and refine those numbers.

The end-of-line solenoid is redundant, you might even say unnecessary. If you live in fear that your first CO2 valve may fail open and poison your fish, you need this. If you have a measure of sanity, maybe not.

Since this system's alkalinity is controlled to 6 to 7 degrees, the CO2 concentration is about 50 ppm. I have learned to watch out for drift in the KH. The stocking level in this tank is high and I feed liberally. The oxygen tension in this system is also vey good. The biofilters are extremely efficient and acidification proceeds apace (in every ammonium molecule conversion reaction two hydrogen ions are evolved). The buffering must answer. I can adjust the daily bicarbonate dose easily, but if I don't test KH frequently I may lapse into instability, and I certainly don't need any more of that.
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Paul G

Active member
Still on the subject of hardware:

Illustrated are the probes and aeration setup. Two small powerheads direct flow over the probes which are secured in magnetic mount probe holders. There are two titanium grounding rods.

Apex turns on aeration if DO, dissolved oxygen, falls below 5 ppm, or if pH falls below 6.5. In this aquarium, plant generated O2 peaks to 10 ppm (super-saturation) by the time SUN 4 lights turn off and falls off overnight to 6 ppm low just before dawn. The pH on either end of the tank seldom drops below 6.5, and that only happens occasionally when the CO2 injection briefly overshoots. So the aeration is only used as a "safety." I also turn it on manually when the pumps are shut down for maintenance.

Other Apex controlled functions have been previously described and are diagrammed above.

The chiller has an internal thermostat system, as most aquarium chillers do, and I set that to 76 F to prevent overheating. I do not use an Apex thermostat program for chiller on-off. I do use an Apex thermostat program to control the heaters. The 300 watt heaters' internal thermostats are set to allow maximum 80 F so they cannot run away, but Apex is set for 77 F. When the heaters come on, power to the chiller is switched off automatically. Also, whenever PUMP 1 is off, CO2 injection, the UVs, the heaters, and the chiller must also be shut down. Apex is programmed to do this automatically.

The CO2 EOL is programmed to turn on when either the CO2 PRIMARY or CO2 BACKUP comes on. The magnetic stirrers under the doser vats are programmed to turn on 5 minutes ahead of any scheduled dosing event, and to turn off when dosing is done. They all run simultaneously regardless of what is being dosed (it's always good to stir the vats).

I use relays (socket extenders) to distribute power sources to high-current loads so as to minimize loading on the Apex energy bars and their associated UPSs. One example is shown here, where 5 amps is switched by a 30 mA relay solenoid. There are reasons why this is done, but I need not go into it here.

This is by no means a complete map of the Apex Aquacontroller or description of its capabilities, but it gives an idea of how versatile and useful it is. You can set up as many timers, thermostats, parameter controllers, lighting and dosing schedules as desired depending on the modules you connect and how you program the system. It is not just for reefers.
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Paul G

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This is the data plot of dissolved oxygen for the last 5 days.

The blue graph is the light cycle. Apex energy bars report their amperage draw. All power sources for the lighting system derive from this particular energy bar, so the current being displayed represents all the energy going to the lights. All during SUN 4 portion of the day, the total current draw of all the lights is between 3 and 3.5 amps.

The red graph is the oxygen concentration, DO, in ppm. The constant background DO through the 24 hour cycle, day after day, is what the top to bottom water circulation patterns and surface agitation characteristic cause it to be. That is the portion contributed by the air-water interface. That flat line is embedded in the data, but cannot be differentiated. Aeration by airstones is not practiced here, so there is zero contribution from sparging techniques. The cyclical variability is imposed entirely by the oxygen production of the aquatic macrophytes in response to the light.

As a generalization, 100% oxygen saturation in aquarium water is 9 ppm. Oxygen-using organisms typically do okay around 3 ppm. Aerobic heterotrophs not limited by other nutrients (but carbon in particular) adjust population response to available oxygen. The biochemical oxygen demand, BOD, of a load of nutrient is the oxygen requirement of the bacterial community to mineralize it to a specified concentration. If nutrient (DOC) is present in the system, the aerobic heterotrophs will remove it so long as there is oxygen available to oxidize it. Aerophilic autotrophs, nitrifiers in particular, require large quantities of oxygen to maintain healthy populations and to convert nitrogenous waste product. When the aquarium environment is polluted to unacceptable levels there is a very high BOD; the heterotrophs are hogging the oxygen.

In a planted aquarium, oxygen is being generated by the plants and light is the throttle. If DO rises throughout the day that is an indication that the ecosystem BOD is being satisfied and nitrification is not being thwarted. If the DO never goes below 3 ppm, even at night, all is well; there is just enough O2 for everyone. If the oxygen tension can be kept higher, so much the better. The best all around oxidizer in the aquarium is oxygen. If the DO goes high every day, over time the oxidation-reduction potential, ORP (or redox), of the aquarium will tend to go high and stay there, assuming no unusual pollution event occurs that floods the system with DOCs.

The O2 evolution in this aquarium is happening on its own terms. It's coming spontaneously from the plants under the light I am providing. I can demonstrate a reduction of peak production by turning down the lights, but the pattern persists. I am hitting saturation daily with the BMLs running at only 60% of capacity. This is one factor helping with alga control - it's only as bright as it needs to be and algae is not encouraged. The normal ORP is consistently high.

I have a significant biological filtering apparatus installed and it is very mature. This can be viewed as a high capacity enzyme reactor that employs a complex community of heterotrophic and autotrophic bacteria populations that oxidizes every labile molecule that enters it. This enzyme reactor needs oxygen in copious quantities to do this. That the DO peaks daily is testament that the system does not run an oxygen deficit. The plants drive the system's oxidative power, optimizing its oxygen budget. To be clear, this works as described only if the plant biomass is high and healthy; that is, if there is sufficient biologically active photosynthesizing matter to fully evolve the oxygen required to make it happen.
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Paul G

Active member

Cryptocoryne has an interesting way of spreading. When I first planted a few individuals, some suffered the 'melt' often seen in this plant, but when left alone they slowly came back. New plants then started to show up nearby. Then, new plants began volunteering at locations remote from existing stands. Evidently the runners these plants send out are far ranging and piles of rocks don't get in their way. I have been using root tabs with this plant. It is a relatively slow grower. Rarely individual leaves melt or detach, but once established whole plants are hardy and can get fairly large. Patience is key to success with Cryptocoryne. It looks great with the big swords.

Paul G

Active member

Three of my fat SAEs. Number four, not so fat, scampered into the bushes just before this picture was taken. I had just put in this wood with some new Java fern stuck on. They took to it right away and seem to like it being there. Another reason I keep the tank covered; these fish can jump and have nervous dispositions.

On the subject of wood (or rock) and epiphytes such as Java fern and Anubias, I use cyanoacrylate - SeaChem Flourish glue - instead of thread. It's much easier and works very well.

Noted just for fun... Wednesday midday a large Nerite snail went for a walk on the oxygen sensor. It spent some time cleaning the membrane before moving on.

Today I did some serious pruning. I removed a lot of Ludwigia and Hygrophila. The Sagittaria has been spreading rapidly. I am letting it fill in through the middle and along the back, but keep it thinned out in front. I inspected the Echinodorus for unhealthy leaves and cleaned them up. I am very pleased to report that I found not a trace of algae anywhere.

Paul G

Active member

After yesterday's maintenance, this morning I broke out the 5" net and dipped out the floating debris and duckweed. Can't get every last bit, but if I spend 15 minutes on it I get quite a lot. I have three little Eheim surface skimmer internal filters that I occasionally use to sweep up the duckweed. The tank is 72" x 24" so I need three to make this an overnight job. One little teeny-tiny scrap of duckweed will proliferate and once again cover the whole surface if I let it. The Eheims do a really good job, and every time I think they got it all at last. But to be honest, I take the staying power of duckweed as a sign of a healthy tank, so, in the end I am always happy to see it come back. I just have to keep after it; it's part of the bargain I've made with nature.

So this is the system this AM. Several large Nymphaea leaves were removed to let in the light, and now several new ones are arising to replace them. This plant is especially important to the system's health. It has the "aerial advantage" (to take a leaf from Walstad's book), and transports voluminous oxygen into the substrate. The whole physio-anatomical nature of this plant speaks to its dominating strategy - it has big leaves that float and an extensive tuberous root system. The rhizosphere benefits similarly from the huge root systems of six large productive swordplants. While they don't grow emergent, they are tank-busters. There is no doubt in my mind that these plants are the key to everything that makes this system work, garden fresh and algae free. Brisk water circulation is important to the health of the jungle - no "dead spots" are allowed.

Today's numbers:

NO3: 5 ppm
PO4: 3 ppm
K: 50 ppm
GH: 92 ppm (5 degrees)
Ca: 60 ppm
Mg: 32 ppm
Ca:Mg = 2:1
KH: 108 ppm
Fe: 0.32 ppm
pH: 6.6
ORP: 350 mV and rising
EC: 700 uS/cm

The GH is slowly descending. This is a desirable trend as the softer water is more appropriate to this type of system. The Ca and Mg levels are more than adequate for the plants.

Hello, ajw9356. There is a lot to learn, but it is a kind of investment. I get satisfaction from the natural art of the results in equal measure to the science study and technological effort that I put into creating it. I think everyone in the hobby makes this deal with themselves at a level that suits them.
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Paul G

Active member

Today I cleaned and calibrated the pH meters. It has been awhile since the last calibration. The probes are double junction lab grade and are both about a year old. The calibration procedure is performed twice with each probe. The probes are installed on either end of the tank. The right end, pH-R, is the sensor for the pH controller, i.e. the CO2 solenoids. The left end, pH-L, is monitoring the pH at the distance farthest from pH-R. Interestingly, they never agree exactly. The pH "officially" stated for the tank is the daily average of the pH-R value.

Also today I switched out the intakes, as the flow rates were slowing considerably. It has been 13 days since the last swap.

The 25 micron filters need changing and I have been putting it off until a day I can spend entirely in the pump room. Then I'll change all 8 filters and be done with that for a while.

Yesterday the CO2 PRIMARY bottle went empty, so a new one was connected. This last 20 pound bottle clocked out at 146 hours. I did not record when it was connected. Hereon I will be noting this so I will have a better idea of how often this is done.

The City of Independence, MO, is noted for supplying some of the best quality water anywhere in the country. The city water department uses chloramine exclusively. I have dual carbon block filters ahead of the RO/DI (reverse osmosis and deionization) system that are designed for superior chloramine removal. A diverter valve is installed on the reject water discharge so the brine can be sampled and checked with a chloramine test strip. I do this about every two weeks. At the first sign of chloramine, a new carbon block goes into the prefilter lineup.

In this RO setup, feedwater input is controlled by a solenoid valve that is switched by a float switch in the RO reservoir. The membrane is automatically flushed for 2 minutes daily, so I don't have to remember to do this. These functions are all executed through the Apex. The TDS meters are monitoring input water, post-membrane water, and output water.
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Paul G

Active member
The mix specification is 300 grams Potassium Nitrate per 2 liters of water. This approximates the concentration of KNO3 in SeaChem Flourish Nitrogen (which also contains urea).

The current dose rate is 1 min, 10 sec of run time on the Milwaukee MP810 peristaltic pump daily, which doses approximately 10 ml/min. If you take all these numbers strictly at face value, you would hold that I am dosing just over 10 ml per day of SeaChem Nitrogen, and, by implication, that that is a recommendation of practice, without specifying a basis upon which this number is derived. This would be an incorrect reading of my method.

There is a source of nitrogen not factored into this which is significant but difficult to quantify with any precision. There are quite a lot of fish and they are fed liberally. Another wrinkle is that nitrogenous waste is consumed in appreciable amounts by plants, and a lot of thriving, productive plants need huge quantities of nitrogen - but, again, it's not possible to be numerically precise.

I test NO3 regularly so I can see how its concentration drifts under current conditions. The mix spec is never changed. If NO3 consistently tests at 5 to 10 ppm, I know that the doser run time, whatever that may be, is maintaining sufficient, but not excessive, concentration. I can adjust the run time to changing conditions. With the lighting now being used and the rate of CO2 consumption, the utilization of nitrogenous nutrient being in lockstep with carbon fixation, what I am actually dosing is - just now - about 12 ml of specified KNO3 solution per day and a whole lot of fish food. As the swordplants grow and put out new leaves, their appetite will only increase. Pruning these tankbusters, and all the other plants too, of course, to sensible proportions puts a ceiling on the nitrogen consumption eventually, but there is no knowing how much is enough, or too little, until the actual ppm number changes.

An aquarium with no plants and one with high plant density and virtually unlimited growth are two wholly different types of aquariums. All conditions being equal, a given nitrate level will either rise or fall depending on the productivity of whatever plants are present. Superimpose on this the whole problem of the size, types, numbers, and eating habits of the fish and the evolution of nitrogenous waste that results, and the possibilities range from doing large regular water changes as the only means of controlling excessive nitrate to adding KNO3 solution as plant food. In terms of numbers, all that counts is the empirical determination of what is actually happening. All aquariums are uniquely different, even if similar.

This applies to all plant nutrients. The key to how much to dose anything is knowing how fast it's being utilized. The dose should be adjusted to specific conditions extant, thus the dosing scheme should be readily adaptable.

We can take this discussion to various other popular dosing strategies being practiced by aquatic gardeners, but I think that would be a digression best left to another context.

So the answer to your question is that how much - or little - nitrate I dose is not directly relevant to how its low concentration is being maintained. The nitrate is completely under the control of the plants.
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