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bobsea
02/03/2010, 07:30 PM
Recently my pH has climbed to 8.6 in the evening (7 PM) and goes down to 7.9 during the night (2 AM). This just started. Last week the range was 8.0 to 8.4. Any ideas on what is wrong? My dKH is about 9.0 and Ca is 370. I dose with B-Ionic; alkalinity 50 ml and calcium 30 ml at about 10:30 with lights off. I have a 75g display tank with a 30g sump (about 75g water in total) and use Kent salt and RO/DI water. I also use a Phosban reactor.

Randy Holmes-Farley
02/04/2010, 08:30 AM
How are you measuring pH?

The B-ionic will boost pH, but I'd double check the calibration before worrying.

pH above 8.5 in the absence of limewater is almost always pH measurement error.

If it is high, more aeration will bring it down.

This has more:

High pH: Causes and Cures
http://reefkeeping.com/issues/2005-03/rhf/index.htm

Chiefsurfer
02/04/2010, 09:37 AM
Also, do you have a refugium running opposite your life cycle? O2 levels will fluctuate your PH(usually not that high tho), SOO if you have a lot of photosynthetic corals in your DT, they will produce a lot of O2 from the CO2 in your system. This will raise your PH while your daylight cycle runs, probably being highest right before or shortly after lights turn off. Then it will be your lowest at night when nothing is producing o2 in your system. A good way to balance it is growing a macro in your refugium, running that lighting opposite the tank's lighting. This will lessen the swing, however may not lower the high-mark.

mcoomer
02/04/2010, 09:39 AM
New test kit? Generally, if your water parameters make a sudden move away from normal I recommend taking a water sample to your LFS and have them confirm what you're seeing.

Mike

bobsea
02/06/2010, 10:07 PM
Thanks for the ideas. I cleaned the probe and calibrated the pH meter (Milwaukee SMS122). I'm getting less variance (8.2 to 8.6). I still need to bring the pH down. You're right I need to set up a refugium lit at night with macroalgae. It should help balance out the pH. I'm also going to do two half doses of the B-Ionic alkalinity, evening after lights off and in the morning.

Randy Holmes-Farley
02/07/2010, 07:54 AM
What time of day do you dose the B-ionic now, and how much?

Adding it all in the AM may be a better plan than adding any at night if your goal is to even out the day/night pH swing (I do not personally thing that is an important goal).

Complete aeration will eliminate any pH swing, again if that is a goal, and will cut down that high end, if it is real and alkalinity is not excessive.

A lit refugium will raise the pH overall. I still think the 8.6 may not be accurate, but if it is, a lit refugium any time of day may raise it further.

bobsea
02/09/2010, 03:54 PM
Thanks again! I've got a few things to deal with (possible electrical current in the tank & a possible malfunction in the pH meter),but first let me answer your questions. I've been dosing at about 11PM after the lights are off, 50ml in total B-Ionic alkalinity, which reads at about 9.0 dKH and 35 ml calcium, which reads at 370. I'll look at complete aeration in the article you suggested. My mag is low (1170) which may be the problem. I read your article and will make the epson salt and mag flake mixture. On my Milwaukee pH meter the slope will only calibrate to 4.4 with 4.0 calibration solution. So it might not read accurately. I've also been getting a slight shock when touching the metal hood and the water, so I've got to eliminate that ASAP.

Randy Holmes-Farley
02/10/2010, 06:00 AM
Yes, the pH measurement is not reliable if 4.0 reads 4.4, and if 7.0 is reading correct, then the 8.6 is a false high reading, and the real reading is lower. :)