I use equal parts Red Pottery Clay and Plantex
CSM+B, but you can tailor it further if you need more macros in the tank or have very little water hardness, etc.
You can add Potassium sulfate, Magnesium sulfate (epsom salt
), Potassium nitrate or Calcium nitrate, etc. You can't add any phosphorus because it will precipitate with the iron in the Plantex and clay, as the clay is iron rich naturally.
The typical mix:
3/4 cup plantex
3/4 cup red pottery clay
2 tablespoons potassium sulfate
2 tablespoons epsom salt
2 teaspoons potassium nitrate.
If it were going in a well-stocked tank, I'd leave off the nitrate.
The trick to it is to add only as much water as you need. I use distilled water, but reverse osmosis filtered water would be fine as well. I use a syringe to gradually add the water, as it takes less than you'd think to mix it to the right consistency. You want to only add enough water, and add it gradually enough, until you can mix and mold the stuff and it's not sticking to anything.
I roll it into small little balls and sit it on some tin foil or wax paper to dry. I usually leave it to dry a couple of weeks or so. I do not bake them, and from talking with others, the results arent very good, they get fragile and crumbly after that.
From there I'd just use it like any other fertilizer tablet
. They dissolve quicker than you'd expect, but they last long enough to get them in the substrate. From there it doesn't really matter because it's all trapped under the substrate. You don't want to hold one under water while you think about where to put it, but you have enough time to get it from your hand to where you want it in the substrate before it dissolves.
Hopefully this helps, especially with the cost of root tabs, and if you already have all the dry ferts, then the clay is the only real setback.
this isn't my recipe just something I found. you can pm me for the cited source