I'm not sure whether this is the right section so I apologise in advance
Last week I pinched some rocks from my mothers flower pots outside and boiled them before adding them to my shrimp/snail tank, I didn't know these rocks could raise PH so I was over the moon when my levels raised from 7.4 to 8.8 in a few hours. The next day I did my water change only to find that the levels were back down to 7.4, the tank is only 2.4 gallon -11 litres and I really want to get strong shells on my snails, I feed them Hikari Crab Cuisine and other calcium enriched foods but there shells are still getting really damaged. In the tank there are 2 baby snails which love to jump off the top walls, which of course is damaging there shells further. I've now replaced the rocks with sand and really need a stable source of calcium for them. I have tried cuttlebone, shells, egg shells but no such luck, I don't really want to add chemicals to the tank but if there is no other reliable method then I guess I could.