PH drops to 7.6 at night, solution??

[sshwtme]

I have a 130 reef. I only dose kalk water. I have never topped water with anthing except kalk water. My PH reaches 8.2-8.4 when the halides are on full power. My alk is around the 8.4-10 dkh. I regulary keep the water buffed. I have a pinpoint PH monitor that I have calibrated three times back to back thinking that was the problem. I checked the PH with my salifert test kit and it showed in the same PH range. Does anybody know a solution to my problem? I am open to any logical answer. I am totally baffled by this. Nothing in the tank seems to be affected by the swing at this point. I just wonder if it is a matter of time before it will.

Thanks,
Lance
sshwtme@cox.net

[Rikko]

I've read a lot about setting up a reverse photoperiod refuge (I'm sure I have the name wrong.. It's off the top of my head). Essentially you run a refugium with a light period that runs more or less when the display is dark. End result is that the natural pH drop you get in the display is mitigated by the active inhabitants of the lit 'fuge. IIRC most people keep macroalgae in there but I'm sure you could go nuts and make a mini secondary display out of it (then again, if it's on all night praps solid black walls would suit the house more).

[PUGroyale]

its typical for the Ph to drop at nite...that seems like a fairly big swing tho...no ideas really...just makin' sure you knew thats normal. you might try and keep it up to 8.4 day - 7.8 p.m. ...think it's ok = )

good point Rikko...I run a fuge' lighted 24/7 or at least overnite this time of year... by doing so it will keep the ph elevated.

[aurora]

As long as your tank inhabitants look happy and healthy.. I wouldn't do anything. Many people have crashed their tank chasing after a pH. Keeping your alkalinity a bit higher could help with your pH swings. Try keeping it about 10-12 instead.

[vonswedge]

If you have a sump or fuge, run a light on it at night. This help me with the wide PH swings.