Wild PH swings in new setup

[jbennicoff]

I have a 75 gallon reef with a 55 gallon sump that has been up and running for about a month. About 100 lbs. of live rock (mostly dry pukani from BRS mixed with some live fiji) I have an apex reading ph and have noticed some pretty wild swings over the last few days. It was rock solid at 8.2 for several weeks but now is all over the place, from 7.3 to 8.6 over a 12 hour period. KH is 9, and I have been adding reef buffer. I think it may have something to do with a hair algae outbreak that I have been fighting to get under control. I have 4 turbos that are starting to make some headway.

Any thoughts?

[ReachTheSky]

Do you notice anything along the lines of sand/rock melting, cloudy water (precipitation) or fish gasping for oxygen? If not, it's more likely a reading malfunction.

[jbennicoff]

The water is a bit cloudy, fish seem to be OK. Just calibrated a brand new probe about 10 days ago. I also checked ph with my Seachem and it checked out. ORP is about 230-250.

[Ruffoj926]

Maybe your ph will spike if using a carbonate based alkalinity supplement. But I can't see a reef tank actually getting down to 7.3 unless you keep all your windows shut and have unusually high CO2 concentrations in the room. Like the other person said, it could be an error. If it's really fluctuating, it will stabilize on its own.

[disc1]

If you see a reading of 7.3 then you have a measurement problem. By the time pH gets that low the rocks and sand will begin to dissolve and that will bring the pH back up to at least the 7.6 to 7.7 range. It is not very realistic to see pH go that low.

[jbennicoff]

Sounds like I need to recalibrate my probe...

[bertoni]

Recalibration is a good idea. I'd also check for electrical interference problems. My pH meter would swing wildly when the lights were on in the tank, so I just measured a cup of water well away from the tank.