Is slate safe


Reefing newb
Quick question. Is slate safe in marine aquarium? Not even thinking at the time I put a piece about 5x6 inches in to make a cave. The tank is about 2 months old. Hope it ok because it at the bottom of about 120lbs of live rock. Not sure if this is the place to ask but do want to know if it will effect water Chem. It is a 120g with 40g sump. Fish an corals. Thanks
Slate can definitely be used in aquariums, but you need to take sensible precautions. I'd steer clear of roofing slate in case it has been treated with chemicals, but natural slate should be fine as long as it is cleaned and soaked first (to remove any water soluble minerals / contaminants.