Help, pH climbing

[JJohn]

So, I need your help. My 75G is a long established mostly SPS mixed reef. It has been setup for eleven years. I can't imagine what has changed. All top off water is with RO/DI and Kalkwasser. Suddenly, my pH has started climbing. I have no idea why. I have graphs going back years and it has never been this high before. It has reached at 8.9 at the end of each photo-period and my acro's are beginning to show stress from this with some tissue loss already. I did many water changes over the last two weeks but the number continues to climb. Any ideas as to what is happening?

I don't test for everything that I know I should but after a decade of seeing the same numbers every week you just stop doing the tests.

Nitrate = 0
Nitrite = 0
Salinity is at 1.027
Ca = 410
Alk = ? (ordered new test kit) was usually around 8-9 dkH I will measure it as soon as I can
Temp 75-80 (I have always run with these numbers)

Other facts: old style tank with low bioload 6 small fish, DSB, a great deal of live rock in both sump and tank, a decent skimmer, and I am running carbon 24/7. I have 5 mj 1200's which cycle randomly for good water movement, 2X175W MH XM 10k's plus two overdriven flourescents. Only bio changes that I have noticed is a sudden appearance of some brownish film like algae and a month or two ago I had some macro-algae go sexual and cloud the tank for a few hours. The brownish stuff is new but I believe it might be a symptom of the problem and not the cause. I have not added anything to the tank in six months. I use Reef Crystals salt and have for ever.

Thanks for any and all help/advice,
John

[Boomer]

Well John that can happen. As CO2 leaves the systems, which plants and many corals take up, it raises the pH. Take a read at this

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

[JJohn]

Thanks for the link Boomer. I had read that article but, the raise I am seeing is excessive. It is well beyond the normal cycle I have observed for over a decade. This afternoon, many of my acro's have begun to die. Today the pH will hit 9.0.

Any idea of why the change and is it the cause or an effect of the whatever is killing my acro's?

Thanks,
John

[bertoni]

That is very high. I would guess that photosynthesis has increased for some reason. Shutting off the lights for part of the day should help. Maybe a bit more food is going into the tank?

[JJohn]

I haven't fed for three days. I typically feed lightly every other day. Could light level changes due to bulbs aging cause this?

[bertoni]

Possibly, I suppose, but older bulbs are typically less efficient, which would tend to mean less photosynthesis, unless the spectral content made the difference.

[HowardW]

<<< I did many water changes over the last two weeks but the number continues to climb. >>>


Just curious, what is the PH of the water you keep adding via water changes?

[JJohn]

Howard: You know, I never bothered to check the pH of the water I am adding. I will do that tomorrow when I change out a few more gallons. I just assummed that when mixed to the proper salinity level it would have a pH of closer to 8 than the 9 readings I am getting now. Definately worth checking.

bertoni: That was what I was thinking... maybe a spectral shift of the MH's are enabling rapid growth of the brownish algae that is starting to show up. And, it is this algae growth that is causing the higher pH. I was thinking the algae growth was a symptom but perhaps it could be the cause of the pH change.

Thanks all, I will keep looking for the cause and a fix. I have already lost half of a 6" diameter colony that I started from a single 1" long frag. Several other colonies have small patches of tissue loss at their bases. I am really bummed as I haven't lost a coral in many years and now I am in danger of losing several. Interesting to note my birdnest colonies look great as due to my monti's. One softy is struggling but the other two are fine. My LTA seems a bit stressed but not in danger. Let's hope I can figure this out.

[Boomer]

John

Drip seltzer water to lower the pH. That is in the article I posted. What you see is not uncommon in tanks that are producing allot of photosynthesis. The pH limit IIRC is around pH 11. It is for this reason Planted FW and Maine Macro tank users often use CO2 injection, to lower the pH.


Howard ma be right if you got some salt with a very high pH, and the WC making it just worse.

[Billybeau1]

JJ, I suspect your pH probe went south on you. They are only suppose to last a couple of years.

One thing you could try is get an Aquarium Pharmaceuticals pH kit and test your water. My AP kit matches my pinpoint pH monitor to a tee.

You may just have to by a new probe. :)

I wouldn,t make any corrections until you are sure your probe is reading correctly.

[rykwong]

Hey Billy,
I know that dosing two-part raises the pH. If you use one of the methods in the article to lower the pH will it just keep going up? Would lowering the pH keep it at a certain level for a while? Or would the pH continue to go up and down? Thanks!

[Boomer]

wong

If one by accident raised the pH up to a high level, then the method would lower it and should not be needed again. If, on the other hand, your pH is climbing due to photosynthesis, then you would have to add it in a continuous bases.

jjohn

When is the last time you calibrated your pH probe ? Also, some new seawater mixes batches will show a pH close to 9 when freshly mixed. After it has sat and aerated for 24 hrs almost all are in the low 8's.

[Billybeau1]

<a href=showthread.php?s=&postid=10119909#post10119909 target=_blank>Originally posted</a> by Boomer
If, on the other hand, your pH is climbing due to photosynthesis, then you would have to add it in a continuous bases.

I think you'll agree Boomer, that, photosynthesis alone will not raise pH to dangerous levels in a marine tank.

High pH is almost always measurement error. In Johns case, I think his probe is bad. :)

[Boomer]

To 9 rarely but to the high 8's is not uncommon if there is tons of photosynthesis going on. That is why many running Macro Algae Planted Marine Tanks use CO2, to keep from getting to dangerous pH levels and to supply a CO2 source to marine plants that use it. In all other cases it should not be an issue. I would suspect the probe is out of calibration or shot to be the first guess but one can not rule out plants.

[JJohn]

Wow! You guys are good. The probe was most of the problem. It was 18 months old. I thought they lasted longer than that. After a recalibration, it is still not reading right. I would probably need to create a better lookup table or polynomial. What threw me off was the sudden change in it's readings. I assumed it had to be the tank not sensor drift. Oh well, live and learn...

It was significantly off. Actual pH (using two probes that at least agree) appears to be more like 8.65 at the peak of the day rather than 9.05 which is what it read this afternoon.

That said, then I still have the recent issue with my acro's. That will probably take some time to figure out. Whatever it was, it seems to be working itself out. I am not seeing any more losses or recession but I am definately not out of the woods yet.

Thanks again,
John

[Boomer]

WOW, two for one issue with pH. That is a first :) Hope things work out.