1. I have a good selection of dry fertilizers (potassium sulfate, potassium phosphate, ferrous sulfate, ammonium sulfate etc.) I also have gypsum (calcium sulfate). Can I combine some of the fertilizers with the gypsum to make root tabs? The gypsum will serve as the slow release binder of the ingredients. Has anyone used gypsum for this purpose and what was the recipe? I read you can use clay, but I was wondering if gypsum would work.
2. I have inert gravel as substrate consisting of pieces that vary from 3mm to about 1cm. I read that root tabs are useful only if you have compact substrate like sand or soil. With a large gravel like mine there is constant water exchange with the water column and root tabs would just dissolve and leak into the water column rendering them useless to the roots. Is this true? I have Amazon Sword, whose leaves are slowly dying, becoming transparent with holes and disappearing over time. Would root tabs save the Amazon Sword in my set-up?
Very large gravel won't hold nutrients, they will leak into the water column. So root tabs won't do anything different than just dosing the fertizilers into the water column.
However, plants can absorb nutrients from the water column just fine. Why not dose the fertilizers directly to the water column? You can use your dry fertilizers to make a liquid solution that you can dose periodically, there's a good explanation of how to do this at https://www.2hraquarist.com/blogs/fe...um-fertilisers
If you have a large aquarium, and an extremely accurate scale, you could measure and dose the dry fertilizers directly, but the liquid solution is usually easier to deal with.
Yes, I prepare liquid solutions and dose the water column. I use the formulas from https://rotalabutterfly.com/nutrient-calculator.php. However, the Amazon sword is still not doing well. I have java fern and anubias. Even the java fern is not growing and very slowly losing leaves over time. Only the anubias are growing new leaves. It is a five gallon aquarium. My nitrates are surprisingly consistently high, around 80 or 40ppm. I thought root tabs may help.
I wouldn't expect root tabs to salvage the situation. With such high nitrates, I'd do a series of water changes to try to bring water levels to more normal levels, and start looking at other possible issues for the plants (lighting, temperature, CO2, etc).
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