Any ideas about low pH?
 

For some reason I don't seem to be able to keep my pH up. It's always around 7.6, even with alkalinity consistently between 10 to 12. Calcium usually 400 to 450. I have supplemented alkalinity with kalk on occasion and brought up the pH temporarily but it always comes back down to around 7.6 even by the next morning.

It's an SPS dominated 50 gallon reef with a 25 gallon sump. Bubble Magus NAC6A skimmer, Chaeto in the refugium portion of the sump. 2 Tunze nanostreams 6045 for circulation in addition to an eheim 1262 for return from the sump. Fish include 2 percs, 2 lyretail anthias, a yellow tang and a royal gramma.

Nitrates are undetectable, phosphates same. Alk like I said usually 10 to 12, calcium 400 to 450. pH is the problem usually hovers around 7.6 and doesn't change much. I have tested with color kits and also have an aquatronica controller. Just changed and calibrated the pH probe.

Everything is healthy, don't get me wrong, but I have noticed that the corals are happier and grow faster when the pH is higher. I get much better polyp extension and growth then. I am considering just switching to kalk for ca and alk and to bring up the pH but I would also like to hear ideas about what could be keeping the pH suppressed. I was under the impression that if I was aggressive at keeping the alk up then the pH would stay high as well, but that doesn't appear to have been the case.

Anyone have any thoughts???

keep all three in check...mag,cal,alk plus make sure your tank is getting good airexchange, alot of people use air exchangers or simply air the house by leaving your window open or door for a bit:)

sorry for not mentioning the mag - it's always 1300 or higher. Don't you think that the skimmer is enough to keep the tank aerated? Just wondering.... I'll try that though, it's easy enough to try.

oh yeah, and I have an orp probe that always reads over 400 and is calibrated frequently.

Low pH is usually from CO2 content. Many people who run Ca reactors experience lower pH. Some possible solutions:

• Introduce fresh air by running skimmer air intake to outside air
• Reverse refugium lighting (refugium lights on when tank lights off)
• Supplement Ca and Alk with Kalkwasser or Calcium Hydroxide (reacts with CO2 and maintains high pH)

a skimmer is enough to keep your tank oxygenated but there still has to be a decent exchange of fresh air and gases like an open top or sump. i dont think its your major problem but allowing in some fresh air wont hurt.

you can use buffers to raise your ph but id find out what your problem is first.i know you said yoiur using a controller but off hand i cant remember if you said the probes are calibrated??:)

my ph drops a little in the winter when the house is all closed up......I think people worry to much about what their ph is....I say, if your big three are good and stable and your ph is somewhat stable(you can expect small swings because of photosynthesis, with your light cycle) then dont worry about it:wink:.....

the fresh air is a good idea. I don't have a ca reactor. The probes are calibrated frequently and were just replaced recently. I do run the refugium on a reverse daylight cycle but it doesn't seem to matter.

I hear you about worrying about the big three only, but I've always found that when I do manage to get the pH up, the corals have always responded well because of it, look healthier and have better PE and growth.

I think I'll set up a kalk reactor for top-off.

The commonts below are accurate. In addition, and as noted previously, keeping pH is consistent is the main concern.

Over my years of reefing I always had a lower pH due to how aggesively I ran my calcium reactor..........it never impacted my corals.

Thanks for your input. I think I'll go with a kalk reactor for now. It will automate my top off and ca/alk supplementation and fix the pH problem at the same time. I have a reactor hanging around so I'll give it a shot.