pH low

I cant seem to get my pH to stay above 8.
My normal diurnal swing takes me from 7.6-8.1 and thats it.And it never stays at 8.1 for more than a couple hours.
My overall average according to my controller is 7.8.
I run Kalk in my topoff RODI water.No other dosing besides TLF NPX pellets and ROX carbon in separate reactors.I also have a large refugium with massive cheato that is lit opposite my display tank.
Reef is just under 2 yrs old.

 

Anything above 7.8 is fine, 7.6 is a bit low. In our systems, pH is a purely a function of alkalinity and CO2. So, either your alkalinity is too low, or your CO2 is too high. If you CO2 is too high, you can run your skimmer line outside, to pull in fresh air. Or, drip kalk, but only if doing so, dosn't push your alkalinity too high. Alternatively, you can buy CO2 absorbing media to run your skimmer air intake through, but it gets very expensive.

 

@M2434 I probably need to go with upgrading the skimmer air.My alk is always fairly high 10-11 primarily due to my salt brand.Ill look into running the line outside the sump.Did you actually mean outside the house? Thanks so much.

 

Yes, outside. Although it doesn't always work, if you live somewhere with high CO2 outside as well. But usually the air quality indoors is much worse.
I'd also verify the reading though, could be a bad probe.

 

Also, BTW, if you are not already running a reverse photoperiod on your fuge, that can help.