Paul G

Active member
Today's numbers

NO3: 0
PO4: 0.17 ppm
K: 20 ppm
dKH: 5.66
dGH: 3.70
Ca: 16.80 ppm
Mg: 5.85 ppm

Potassium now showing at the expected reduced concentration with alkalinity unchanged. Dosing of K2CO3 to be increased 50%. ODE = 4.5 L, GH now inclining slightly so I'm leaving the ODE there.

Paul G

Active member

After several days of testing zero NO3, but normal PO4, I have a concern about nitrogen insufficiency. Certainly DIN is being continuously evolved, but between more sparing feeding and increase in SWCR rate, there is no surplus water column NO3. To the extent that nitrogen is bioavailable from all sources, the plants are consuming it. Last night and again this morning, 15 mL KNO3 w/urea (SeaChem Nitrogen), was added. In the newly accelerated SWCR, a dose will be calibrated to assure non-zero NO3. Something learned in the past few months of trials in this water change scheme is that maintaining non-zero nitrate derived solely from fish food can result in DOM levels that are difficult to manage, even with liberal application of chemical filtration media. Though attractive is the idea of gaining growth factor nutrition from natural outfall of environmental metabolism, it does not work so well in what is essentially a closed system due to unavoidable concomitant generation of dissolved organics. This accentuates the superiority of water change over chemical filtration for pollution control in closed systems. It is preferable to resort to pure supplementary NO3 in correctly calibrated dosage and to double down on all DOM reducing strategies, in particular water changes. It is a mistake to infer low DOM from low DIN and low orthophosphate. True oligotrophy is defined by diminished figures for all three of these parameters. The problem arises from the relative difficulty in reliably measuring DOM. Redox potential should be a fairly good indicator, but my data shows that there is more to it. I am convinced that DOM is a primary growth factor in algae population. Incipient nuisance algae is an indicator of high DOM, and the relationship of this condition to ORP is not so straightforward as I had expected. A highly oxidizing environment certainly will derive from persistent high oxygen tension, but this does not necessarily ensure that DOM is not also present in larger than expected concentrations. I have been puzzling over the gradual eutrophication of this system while seeing very high ORP and very low DIN. Overfeeding will eventually manifest and cannot - cannot - be corrected with activated carbon, regardless of the charge weight.

The SWCR does work, and is best at high change rates. As long as various means of supplementation are implemented to provide stable background chemistry and sufficient plant nutrient, the faster the turnover the more efficiently does the system shed DOM. The Hardness Reconstitution Reactor (HRR) and K2CO3/MgSO4 dosing can be adjusted with relative ease to attain K+, Ca++, Mg++, and CO3-- at appropriate concentrations. This strategy for maintaining a planted tank indefinitely through automated techniques is highly promising. Just now it looks like fish food provided sanely will support non-zero orthophosphate within oligotrophy. Supplementing with KNO3 to satisfy nitrogen requirement is a simple matter.

Today's numbers

NO3: 0.89 ppm
PO4: 0.12 ppm
K: 15 ppm
dKH: 5.60
dGH: 3.59
Ca: 17.6 ppm
Mg: 4.88 ppm

Potassium and alkalinity falling behind the SWCR. I am increasing K2CO3 to 120 seconds per dose, 20 mL three times per day (= 60 mL daily total).
Magnesium also a bit short. I am increasing MgSO4 to 120 seconds per dose, 20 mL twice a day (= 40 mL daily total).
I am restarting KNO3 w/urea (SeaChem Nitrogen) at 5 mL (30 seconds) once daily.
All subject to revision as the situation develops.

Pretty clearly, the increased SWCR rate is effectively diluting the water column. The reduction in DOM is having an immediate impact. Confidence is high that the lighting can be increased, as is the plan, without occasioning onset of excessive algal growth. It has taken just a couple of days for this to prove out, as much of the scuzzy periphyton has spontaneously abated, as has the stubborn recurring oil slick.

Consideration of effects to micronutrient/trace is due. At present I am not compelled to increase doses here because I have no data, but this will not be neglected.

Paul G

Active member
Today's numbers

pH: 6.65
ORP: 323 mV
NO3: 1.55 ppm
PO4: 0.26 ppm
Fe: 0.29 ppm (@ 08:00)
K: 30 ppm
dKH: 6.33
dGH: 3.70
Ca: 17.6 ppm
Mg: 5.37 ppm

This AM I added 20 mL Brightwell FW Razor and 100 mL Dr Tim's Re-Fresh. Also added a third daily 20 mL dosage of MgSO4 solution at 17:00. Alkalinity and potassium coming back into line. HRR and SWCR are balancing on a desirable calcium number.

Paul G

Active member
Today's numbers

pH: 6.68
ORP: 336 mV
NO3: 1.77 ppm
PO4: 0.30 ppm
Fe: 0.19 ppm (@ 07:48)
K: 30 ppm
dKH: 6.78
dGH: 4.48
Ca: 18.40 ppm
Mg: 8.30 ppm
Ca/Mg: 2.2/1
TDS: 290 ppm
DO: 8.2 ppm
CO2: 40 ppm

Data suggests that no alteration in dosing rates of Flourish Comprehensive or Flourish Trace are needed to answer to the accelerated SWCR. An appreciable level of Fe is testable within two hours of the first daily dosing event. I plan no change in the Excel or Advance dosing either.

As usual, numbers stated for those parameters that normally fluctuate throughout the diurnal cycle are total daily running averages (TDRA). The background chemistry just now is ideal, and nutrient level is oligotrophic. I suspect, watching numbers rise as they have over the last few days, that a small additional water change may be in order just to define an upper limit to the tendency toward "creep". Will the small water change attendant to a filter change event be about the right amount? Today is 17 days since the filters were last serviced. Thursday next would mark the 3 week filter change interval, but I am doing it today.

LOOP1L velocity 145 gph
Stage 1: 100 micron mechanical, no core medium
Stage 2: 20 micron mechanical, 800 grams Renew w/ 250 grams Purigen

LOOP1R velocity 112 gph
Stage 1: 100 micron mechanical, 250 mL Purigen*
Stage 2: 20 micron mechanical, HRR core**

LOOP2 velocity 320 gph
Stage 1: 100 micron mechanical, no core medium
Stage 2: empty

LOOP3 velocity 223 gph
Stage 1: 100 micron mechanical, no core medium
Stage 2: empty

*Purigen charge from previous filter change, rinsed and returned. Based on lightness of color, this appears not to be exhausted.

**The Reef Reactor (HRR) should be removed and rinsed thoroughly. It is a porous medium and will support biofilms. Unclear that colonization interferes with dissolution of material, but in any case I don't need the HRR to become a bio-filter.

All 100 micron filter cartridges were dirty enough to justify replacement at two weeks. Opening these filters results in a water change of about 5 gallons. I also moved nearly 3 gallons to the Q tank to top it up. I will regard this as an 8 gallon "big gulp" water change for practical purposes.

The MD55RLT pumps have been running 24/7 for over ten years now. Pump #3 is showing its age. Dealing with this may occasion a total redesign of the circulation system with some simplifications I have been thinking about.

Paul G

Active member
Today's numbers

NO3: 0.88 ppm
PO4: 0.54 ppm
Fe: 0.25 ppm (@ 09:28)
K: 35 ppm
dKH: 6.67
dGH: 4.03
Ca: 17.6 ppm
Mg: 6.83 ppm
Ca/Mg: 2.6/1
TDS: 300 ppm

Hardness numbers are down a bit as expected after yesterday's 8 gallon water change. If the HRR is outrunning the SWCR, how fast these numbers rise will determine the next ODE timer increase.