How can I stabilize my PH? I have a 55 gallon that has been up and running since Thanksgiving. I have added crushed oyster shell to raise calcium for the snails and to add hardness to the water. I've occasionally added dissolved baking soda to raise PH. At last test (3/26) KH was 2 GH was 14 CA was 100 Ammonia 0 Nitrite 0 Nitrate 60 PH at that time was 7.4 I removed the oyster shell This morning I did just the PH test and was unable to get a reading. I added baking soda and retested and was able to raise the PH to 6.4-6.6 at this time I'm not looking to chase a particular #, I'd just like to have it stable in the safe range. Any suggestions? I am traveling tonight and tomorrow but will redo all my tests on Sunday, along with a water change.