Shells bring pH up, not down. To go down you need acid. Nothing wrong with a pH of 7 anyway.

Quote Originally Posted by swamp creek farms
I check the PH all the time. I added sea shells to my filter the other week and it didnt even change the PH at all. I was hoping it would bring it down to 6-6.5 but the PH is always around 7. I live in the country and I'm on well water, which is 7.0 PH.