I have read many times in different threads to crush coral to help ph from getting to low. My question is must I actually crush the coral or could I just put a few pieces in my hang on filter or in my flower pots? My tap is 7.8 but after a week its down to 7.0. Also if I don't keep a eye on things its gotten down to 6.8 on me once.

ClearWater, I wouldnt' use just any coral, especially not the ones collected from the ocean. They might harbor things that you don't wonna have in your tanks. In my area the fish stores sell crushed coral in 10 lb bags or more, and that is the perfect stuff for keeping pH stable. Check out their salt water section, thats where you usually find it...

oops. I got my coral down at the beach. As of yet no bad thing have happened. The coral has been in for about a week and a half. Thanks for the advice.