EI dosing connundrum
So I have been trying to follow the EI low light weekly dosing regimen for the past couple of months. I also test my water regularly and have noticed that my nitrate levels are almost always around 20 ppm, even after my 40% water change each week. I've never seen them higher than 40ppm, but never lower than 20ppm either. I'm guessing this is mostly due to having a high bioload with my fish. So I'm trying to decide whether I should stop dosing KNO3. I obviously have enough nitrogen for the plants. But if I do that, I will also lose my biggest source of Potassium, right? Is there something else I can use to get the Potassium? I have some Seachem Equilibrium, which has a pretty high Potassium content, but it also has a lot of Ca and Mg. Since my water is already pretty hard (~400 tds) with high kh/gh, I'm hesitant to use that as potassium source. Is there something that would work better? Or is my thinking just way off on this whole thing?