Any ideas about low pH?

[nlreefguy]

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???

[reefwars]

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:)

[nlreefguy]

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.

[nlreefguy]

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

[sphelps]

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)

[reefwars]

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.



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??:)

[fishytime]

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:.....

[nlreefguy]

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.

[wickedfrags]

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.

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)

[nlreefguy]

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.

[abcha0s]

I'd check your probe calibration. Maybe your test kit is giving a false reading and your probe is calibrated to an incorrect set point. If your using a calibration solution, make sure that it is temperature adjusted. Clean the probe before calibrating, but let it readjust to the tank water for a day or so first.

Try testing a cup of water outside of the tank. Perhaps there is interference, from stray voltages or other probes.

I think with some controllers, the temperature probe acts as a ground. Try moving the Ph probe closer or further from the temp probe.

Take your test kit to a LFS and test their water. See if they get the same result with their probe or test kit. I had a similar problem and when I replaced my controller the new Ph measurements were much closer to where I wanted them to be. Lots of testing later, I decided it was accurate.

What you reay don't want to is to increase your Ph to 9.0 because your reading was out by .5

- Brad

[Aquattro]

Just a "for what it's worth" experience. I once found my pH was reading 7.6 or lower consistently. I panicked, and started trying to figure it out, tons of reading, a couple of discussions with Randy Holmes-Farley, testing at the LFS, etc. Realistically, if it was really 7.6 or lower, I should have seen my tank contents dissolving. I got new probes, new test kits, and kept getting low readings (I too was aggressive with my Ca reactor). I eventually solved my pH problem by throwing my meter over my back fence. That particualr tank went several more years successfully growing corals to the point I had to throw frags over the same back fence.

I think sometimes we worry too much about things we shouldn't...

[sphelps]

A low pH won't typically cause issues but the thing with corals is they can usually handle one or two issues without concern but add a third and you could be in trouble. Just like in the wild the increased amount of CO2 is lowering the pH but it's not until other factors including elevated temperatures are added that the reefs become really vulnerable.

So although a low pH isn't a huge concern it will make your reef more vulnerable if you experience temperature or lighting changes. It's also a pretty easy fix with Kalk which will also precipitate phosphate so a win, win situation. Just always remember to make changes slowly.

[reefwars]

I eventually solved my pH problem by throwing my meter over my back fence.




haha priceless and effective love it:):) calibrate it right over the fence !!!:)

[randallino]

nlreefguy, FWIW I noticed this past week with a house full of guests (in laws :confused:) and cooking that my ph dropped to 7.7 - 7.9 but dkh numbers where in 8-9's. But I soon as the house was aired out the ph came back up in the 8's.

[paddyob]

nlreefguy, FWIW I noticed this past week with a house full of guests (in laws :confused:) and cooking that my ph dropped to 7.7 - 7.9 but dkh numbers where in 8-9's. But I soon as the house was aired out the ph came back up in the 8's.

So while having company and cooking dinner you were testing your tank? That's dedication! HA HA!

[nlreefguy]

Thanks for all the advice guys, I started up the kalk reactor so we'll see what happens. I'll make a very gradual change to the pH. Every test kit I've ever used and the ones at the LFS as well were all showing my pH at 7.6 or thereabouts. I know it's not a huge cause for concern and I wouldn't worry about it at all normally but last week I dosed kalk by hand a few times and I just found that the corals seemed to really appreciate it. Was it the pH? I don't know, but I'm dosing kalk now anyway so whatever!

[Borderjumper]

I'm with Brad.. Consistancy is the key.. If your tank wants to be 7.6, let it.

I used to stress about mine.. Bumped it up every night just to see it back down in the morning. My corals started looking like poo from the constant change... So I quite checking. It's been prolly 2 years since I checked ph.. And things are doing well enough.

[Myka]

Just a "for what it's worth" experience. I once found my pH was reading 7.6 or lower consistently. I panicked, and started trying to figure it out, tons of reading, a couple of discussions with Randy Holmes-Farley, testing at the LFS, etc. Realistically, if it was really 7.6 or lower, I should have seen my tank contents dissolving. I got new probes, new test kits, and kept getting low readings (I too was aggressive with my Ca reactor). I eventually solved my pH problem by throwing my meter over my back fence. That particualr tank went several more years successfully growing corals to the point I had to throw frags over the same back fence.

I think sometimes we worry too much about things we shouldn't...

Excellent post. Couldn't agree more.

Personally, I think if you've done everything to try to raise pH naturally and none of that works there is no reason to push the problem.

One other thing to think about is the fact that organic breakdown creates different acids as by-products. These acids will affect pH as well, so preventing organic breakdown is another way to raise pH. The use of a good skimmer to remove organics before they breakdown, well designed flow to prevent detritus settling and breaking down, light stocking of fish to minimize fish poop and excess food, and possibly the use of a filter sock or floss media to catch suspended materials (changed at least twice weekly) are all good ways to prevent organic breakdown.

Usually nitrate and phosphate are signs of organic breakdown, but a well maintained tank will process these nutrients so you don't get a reading on your test kits.

[Abe]

Hmm I just had an idea, if a low PH is the cause of high CO2 from the house not being aired and such. If I add a small air pump to the sump let's say, do you guys think this will help to bring the PH up?.

[hillegom]

Hmm I just had an idea, if a low PH is the cause of high CO2 from the house not being aired and such. If I add a small air pump to the sump let's say, do you guys think this will help to bring the PH up?.

As posted earlier, yes. IF your air pump intake is drawing from outside.

[abcha0s]

Hmm I just had an idea, if a low PH is the cause of high CO2 from the house not being aired and such. If I add a small air pump to the sump let's say, do you guys think this will help to bring the PH up?.

This should have no effect if you are running a skimmer. The skimmer will equalize the water chemistry faster than any air pump. If you don't run a skimmer, that would be a good starting point.