Is ocean rock ok to use in a tropical aquarium?
Anything from the ocean should not be used in a fresh water aquarium. there is more issues than just an elevated ph. First, the rock and everything on and in it will die off causing a smelly mess in your freshwater tank. If you recure it another way and kill everything off then you can use it. Rock that comes from the ocean doesn’t always change the ph. the salt and calcium like shells will do that. Cure the rock in fresh water. Then let it sit in a bucket and test the ph to see if the rock you chose is neutral.