Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Hola, el heb
If you have some of this fertilizer I would test the clay balls in a separate container, not with fish. Perhaps a bucket.
Make half a dozen clay balls.
Place them in the bottom of a bucket.
Cover them with sand, or fine gravel.
Put a small bubbler or fountain pump in the bucket so the water is pumped straight up. Do not bury either of these in the substrate, though.
Test with all your test kits for ammonia, nitrite, nitrate, GH, KH, pH, TDS and all other tests you have.
You can add dechlorinator to the water if needed.
Run the test for a couple of weeks or longer.
The clay balls are supposed to slow down the release of the fertilizer. You want to make sure you are running it long enough to see what happens as the clay balls release the fertilizer.
If you see ammonia or nitrite this suggests the fertilizer is too high in that particular form of nitrogen, and is not a good idea in an aquarium. If the GH, KH or pH are rising then either there are minerals in the clay or in the fertilizer that are entering the water column. This may not be a problem if that is OK with the fish, but for soft water fish this is not very good.