Today's numbers
pH: 6.73
ORP: 467 mV
NO3: 0.5 ppm
PO4: 0.23 ppm
Fe: - n/t -
K: 40 ppm
dKH: 6.84
dGH: 3.59
Ca: 16.00 ppm
Mg: 5.85 ppm
Ca/Mg: 2.7/1
These numbers are posited as ideal target values for this aquarium. The HRR/SWCR balance seems to be holding. The following is a formalized summary.
This relationship is essentially a prediction constructed on an original determination of the volume of water discarded over a specified time period, and the rate of dissolution of the ion source. The means of achieving balance is therefore experimentally dependent on the constancy of these two factors; it is a prediction. There being no actual feed-back loops in operation by which this relationship is automatically regulated, this balancing act cannot be properly called "homeostatic". An idealized mechanism to obtain balance would be a true feedback channel governing generation of free ions based on their concentration in the water column. Homeostasis is very high stability because the feedback loop operates constantly, either by true continuity or by a regime of small discrete quanta that resembles such continuity for all practical purposes (for instance, control of CO2 diffusion as a response to pH changes). There being no simple and reliable fully automatic aquarium technology answer to this for control of GH, maintaining the balance consists of predicting the condition from known controlling factor values, and having the facility to alter those factors as required. The feedback loop is not physiologically intrinsic, so is not homeostatic; but the predictability of the system's behavior emulates homeostasis: Artificial Homeostasis. In this case, it is the timer that provides a virtual feedback loop.
SWCR, Streaming Water Change Regimen, is an automated method of discarding a highly significant portion of the waste products of environmental metabolism while supporting stability in the background chemistry and provision of important macrophyte nutrients. It is a program for artificial homeostasis. Success of the method is defined by maintenance of constant parameters for an indefinite time. The two principal balance systems in operation are the SWCR<-->CaCO3 Dissolution Reactor, and the SWCR<-->K2CO3/MgSO4 Supplementation. This regimen is an ODE (open drain event) hourly, 24 times a day. Each ODE is 150 seconds for a water volume of 5.6 liters.
The HRR, Hardness Reconstitution Reactor, consists of 1.5 kg of SeaChem Reef Reactor packed into a mechanical filter core; works as a no-bypass dissolution reactor with a water throughput velocity of 100 to 120 gph. Reef Reactor medium consists primarily of CaCO3 and is essentially an aragonite substrate type of material. Contributor of both Ca++ and CO3-- ions, this medium supports system GH and KH. This circulation loop runs constantly 24/7.
K2CO3 Supplementation consists of an aqueous solution of 150 grams (110 mL fine granular) Food Grade K2CO3 per 190 mL DW. Contributor of K+ and CO3-- ions, this supplement supports the larger part of system KH (buffer) and provides macronutrient K+ in luxury uptake availability. The daily K2CO3 solution dose is 10 mL at each of the following times: 06:00, 09:30, 13:00, 17:00, and 19:00.
MgSO4 Supplementation consists of an aqueous solution of 150 grams (140 mL coarse crystalline) USP Grade MgSO4 per 190 mL DW. Contributor of Mg++ and SO4-- ions, this supplement is, as the predominant source of secondary macronutrient Mg++, the complement with Ca++ to maintain prescribed GH. This supplement also supplies sulfate which is the source of secondary macronutrient sulfur, far in excess of requirement. The daily MgSO4 solution dose is 10 mL at each of the following times: 06:00, 09:30, 13:00, and 17:00.
TDS, Total Dissolved Solids, is the combined effect of all ions in aqueous solution. The Milwaukee Instruments MC-410 gives a direct read-out of TDS with a resolution of 10 mg/L (ppm). Today, TDA started at 280 ppm at sunrise (tank time), bumped to 290 ppm by mid-morning, then to 300 ppm by mid-afternoon, then to 310 ppm by early evening. These changes correspond to the supplement dosing schedule.
Specifications subject to change, as adjustments may be required to fine-tune the system and correct for drift.
