I'd like to raise the ph in my tanks. I'd like to keep my snails healthy and happy but it appears that my ph is too low for them. Their shells are starting to erode. I've heard using seashells to raise ph. I have seashells but not exactly sure how many to put in or if they need to be crushed up first. I've also heard that crushed coral could be used but I have no crushed coral at home. What is a good ph level for snails? My ph is usually 7.0