I have a 75 gallon reef tank with about 75-80 lbs live rock, 3-4 inch sandbed, 20 gallon long sump (reverse lighting schedule for cheato). I can't seem to get my pH above 8.0 (tested at the end of the day). My dKH
is around the 8/9 range and calcium is around 420-440. All test kits are API. I'm using an in sump protein skimmer which should be oxygenating the water, and I have one powerhead and my return agitating the surface of the display tank and the pH refuses to move.
I've thought about dosing kalk
in my ATO to raise it up a little, but wouldn't that make my calcium shoot too high? I'm doing weekly 10 gallon water changes, and plan to switch to reef crystals when I run out of salt. I'm using Coralife sea salt right now, because it was the only salt they had available last time I needed to buy any, and it was on clearance for half off.
I realize that 8.0 pH is on the low end of acceptable but also that pH drops when the lights are out. And my pH does drop at night to 7.8 or 7.6 according to the API kit.
Any suggestions are more than welcomed!!