Originally Posted by Autumnsky
Do you top off your tank water with tap water? If so this is adding more hardness / minerals by water evaporating and leaving them in the tank.
This brand rock I am not familiar with, but the stones look like normal river stones.
You can take a hand full of the assortment of stones, let them dry and try a vinegar test. Basically just add some vinegar and see if they fizz. You might try some of the light colored ones in a separate test and see if they fizz. I doubt it.
Are you using any additives?
Do you have any large decorative stones?
Hello, Thanks for comments.
No, I don’t top off the tank. When I do water changes (last three changes anyway) I’m using half reverse osmosis water and half tap. I have seen the hardness come down somewhat, which I believe is good.
The substrate: yes, I did that- took a handful out, dried, poured vinegar on it. No fizz. Also, I don’t have any other larger rocks in there.
Lastly, no additives either. A month or so ago I treated the tank with Epsom salt and I’m sure there’s still residue of that in there, decreasing with water changes. The hardness was REALLY high after that.