[stapet77]

We have had our tank for about 9 months now and everything is stabilizing nicely. We finally got our nitrates down to about 5, and Alk 5-6 meq/l, Mg 1200, Ca 400, temperature 77-78, salinity 1.024-1.025. However, every time we get our pH up to 8.3 using buffer, it drops overnight to 8.1 and does not go up again the next day. I realize it is normal for it to drop at night, but it never goes back up. According to SeaChem these values for Mg, Ca, and, Alk should be right on. Are there trace elements that could affect the pH? Is there anything else besides an ionic balance that could cause consistently low pH? We are using purigen, Phosorb, and deNitrate, and Stability (with water changes) - all by Sea Chem. These are the only other additives we use.