Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Dry potassium nitrate (KNO3, mainly provides nitrates to plants) And potassium. If the NO3 level in the tank is holding stable, then that is a good amount to dose for the nitrogen.
Dry monopotassium phosphate (KH2PO4, mainly provides phosphates to plants)Yes, phosphate. While there is also potassium, the dose is so low it almost does not count, but there is a little bit there.
Seachem Equilibrium (mainly provides potassium, calcium, iron, and magnesium to plants. My water is soft-moderately hard)Extremely low dose of Fe. If the GH of your water is over 3 German degrees of hardness, then the Ca and Mg are probably in the right range for the plants. If your fish want harder water (higher GH) then dose to suit the fish. Otherwise, a low dose (enough to raise the GH 1-2 degrees is fine, and a reasonable way to be sure there is Ca and Mg available. Yes, it contains potassium, too, and it might be a reasonably supply, depending on how much you need. Treat it as a Ca and Mg supplement, though, and dose to supply these elements.
Seachem Flourish (all around fertilizer with lots of different elements in it) Actually, Comprehensisve is more of a source of micros. While there are some macros in there, it is too low to really treat it as a source of these elements.
Seachem Excel (not really a fert but provides carbon to plants, increasing the uptake rate of minerals/ferts) Yes, a carbon source.
runninthruthe6, the "EI light" or "Non CO2" version of EI has modified levels, modified dosing to suit a low tech tank. While Excel is providing some carbon, it does not behave the same as CO2, and the reduced dosing of ferts suits a low light tank with (or without) Excel. The concept is similar: Give the plants plenty of ferts, but with the understanding that lower light and less carbon will make the plants grow slower, so they do not demand the same level of ferts as the original EI concept (based on high light and CO2).
I modified the EI method into something a lot like that, basing my changes on water test results.
Fish food can supply most of the elements that plants need, but tends to be low in K, Ca, Mg and Fe.
Water changes with GH > 3 degrees supplies Ca and Mg (unless there is something odd in the balance of Ca and Mg).
Fertilizers that will be in shortest supply in a low tech tanks are K, Fe and C. Dose first to keep these up. (K2SO3 for K, Chelated iron for Fe, Excel for C)
Then supplement the NO3. Dose a small amount of KH2PO4, depending on how much KNO3 is needed.