pH Rises.....Any assistance?
 

So I have a refugium with a 8K light and lights on my main tank. When I do a water change my Ph is at about 8.2. Over a period of a day or two it seems to rise slowly to about 8.4. I am not sure if 8.4 is high for my reef but either way I am trying to figure out why it rises. I usually use some vinegar every couple days to lower it back to 8.3 or so. I do have a kalk reactor and I do dose with an auto top off (Tunze Osomolater). Not sure if I am putting too much kalk in but I was under the impression that the reactor/auto top off combo should stabilize this? Any help would be appreciated.

pH 8.4 is just fine. Up to about pH 8.55 is also fine. Above that, and the higher it is the worse it is, precipitation of calcium carbonate can become a problem on heaters and pumps, etc.

These have more:

Reef Aquarium Water Parameters
http://www.reefkeeping.com/issues/2004-05/rhf/index.htm

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

from the second one:

What is the Acceptable pH Range for Reef Aquaria?

The acceptable pH range for reef aquaria is an opinion rather than a clearly defined fact, and will certainly vary based on who is providing the opinion. This range may also be quite different from the "optimal" range. Justifying what is optimal, however, is much more problematic than justifying that which is simply acceptable. As a goal, I'd suggest that the pH of natural seawater, about 8.2, is appropriate, but reef aquaria can clearly operate in a wider range of pH values with varying degrees of success. In my opinion, the pH range from 7.8 to 8.5 is an acceptable range for reef aquaria, with several caveats. These are:

That the alkalinity is at least 2.5 meq/L, and preferably higher at the lower end of this pH range. This statement is based partly on the fact that many reef aquaria operate acceptably in the pH 7.8 to 8.0 range, but that most of the best examples of these types of aquaria incorporate calcium carbonate/carbon dioxide reactors that, while tending to lower the pH, also tend to keep the carbonate alkalinity fairly high (at or above 3 meq/L.). In this case, any problems associated with calcification at these lower pH values may be offset by the higher alkalinity. Low pH stresses calcifying organisms primarily by making it harder for them to obtain sufficient carbonate to deposit skeletons. Raising the alkalinity mitigates this difficulty by supplying extra bicarbonate.

That the calcium level is at least 400 ppm. Calcification becomes more difficult as the pH falls, and it also becomes more difficult as the calcium level falls. It would not be desirable to push all of the extremes of pH, alkalinity, and calcium at the same time. So, if the pH is on the low side and cannot be easily changed (such as in an aquarium with a CaCO3/CO2 reactor), at least make sure that the calcium level is acceptable (~400-450 ppm). Likewise, one of the problems at higher pH (above say, 8.2, but getting progressively more problematic with each incremental rise) is the abiotic precipitation of calcium carbonate, resulting in a drop in calcium and alkalinity, and the resultant clogging of heaters and pump impellers. If the aquarium's pH is 8.4 or higher (as often happens in an aquarium using limewater), then it is especially important that both the calcium and alkalinity levels are suitably maintained (that is, neither too low, inhibiting biological calcification, nor too high, causing excessive abiotic precipitation on equipment).

Great info but how can I get my Ph to stay lower then it is? Today it is 8.45. It keeps rising.

That pH is fine. Many reefers would prefer it to the lower values they have.

That said, do you know it is accurate? Almost all cases of pH too high (above 8.55) in the absence of limewater (kalkwasser) are measurement error.

What is the alkalinity? If it is not too high, then more aeration will bring the pH down a bit.

Alkalinity is fine. It is at 9.5 dKh. I am pretty sure it is accurate. I re-calibrated my probe but before that I used a test kit ant it was reading 8.4.

That's perfect. I don't understand what you want to change or why.

Thats because it keeps rising. I have been dosing vinegar every couple days to keep it at 8.3-8.4 If I didn't it would just keep rising. I need to figure out a way to stabilize it. That's my concern currently.

No, stop adding vinegar. There is no need, and the pH is not generally rising unless you add high pH additives. More likely the pH calibration is drifting, which is not uncommon. :)

Well I dose kalkwasser. So it is possible that is the cause. However, I am using a reactor with auto top off so I would assume it should not be rising?

pH does not generally rise over time in aquaria unless you change what you are doing.

pH is determine ONLY by the CO2 level in the water and the alkalinity. Nothing else. So unless you change those somehow, pH won't continually rise.

I'd recalibrate the pH meter before worrying any further, and in any event, would not worry unless the pH got above pH 8.5.

If it does, more aeration will always tend to bring it down (but it won't if it is a faulty measurement).

Well my pH is still rising daily and will not stop. Not sure what else to do. It must be due to my kali reactor. I might have put too much kalk in the reactor which is causing it to rise. Not sure what else to try.

Limewater has a huge pH effect on the water, and if you are dosing more now because evaporation is higher, or a more concentrated solution is being made, then yes, pH will rise.

How high is it?

Aeration or less limewater are the best options.

Anything else you'll have to do every day, like adding some CO2 or vinegar or vodka, etc..

I think my solution is more concentrated then normal. I might have up more into the chamber then I should have. I am probably going to empty it out and see. My ph is now at 8.5. It went up from 8.25 to 8.5 over night. I have been having to do water changes to lower it. I have a lot of aeration in m ozone reactor, skimmer, and power heads in the tank.

Water changes are not really a suitable way to deal with pH issues of any kind.

What is the alkalinity? The higher it is the higher the pH will be, but perfect aeration will drive the pH down below 8.5 unless the alkalinity is 14 dKH or higher. :)

I checked the ALK tonight and it is stable at 9 dKh. I also removed all the kalk in my reactor and reloaded it. Currently the pH after a water change today is at 8.25. I am going to see how it goes for the next few days. I usually keep my lights on 10 hours a day and my refugium lights on 14 hours a day. So the pH should not rise like it has been. We will just have to wait and see. I did do a test for the last few days and bypassed the kalk reactor and the pH actually was pretty stable which led me to believe the kalk solution is too much. We will see.

:thumbsup:

Have you recalibrated the pH probe recently?

I had similar whacko pH numbers recently. Not my probe, no sir. Finally I checked the probe. When I calibrated it the previous time, I hadn't rinsed it off and when I pulled the lid off, I saw some of the blue high calibration fluid still in there. I felt dumb, but happy I'd solved my crazy pH numbers. I think the moral of my story is it never hurts to check.

I actually re-calibrated the probe to make sure. It is definitely my kalk reactor. I am going to give it a few days and see what happens.

NOte you're using a kalk reactor rather than a kalk reservoir---how often do you have your stirrer running? I stir my reservoir about once a month. If it's stirring it more than once a day, or if the thing fires kalk into the tank after it's just stirred, that could cause a spike, since kalk itself has a ph of about 12.

It's a reactor. I have a fresh water reservoir that sends water through the reactor on an auto top off. It is pump driven and it is mixed 4 times a day. I think there was just too much kalk in the reactor. Going to give it a few days. Only been going for a day so we will see how stable it is.

So I went ahead and recalibrated my pH probe. I am going to see how it goes for the next day or 2. Today when I woke up in the morning the pH read 8.28. By the end of the day it read 8.45. I now recalibrated it and going to see what it shows for the day and evening and morning and go from there. I am not sure what else could be raising the pH so quickly.

FWIW, those last numbers (8.28 to 8.45) are perfect and not unusual for a tank using limewater, IMO. :)

I totally agree but they keep rising. I will take a look today after recalibration. Overnight it did not rise so I think it might have been a calibration issue. I will keep you posted.

I hate to jump in on someone else's thread, but I am having the same issue. My tank is fairly new, about 2 months old, and recently (this week) my PH started constantly rising. When I first got the tank running, my PH was around 8.0-8.2. It's at a point now, that when my lights are on during the day, the PH climbs to 8.6. I am using my Apex probe, which was just calibrated a few weeks ago. I also verified with another test kit, so it isn't the probe calibration. I do 2-part dosing and try to keep my numbers at alk-8, calcium-450, mag-1350. I've had to dose to keep alk and mag up, but calcium has pretty much stayed at 450 without dosing. I am pretty much stumped on what to do. I've tried aeration, but that seems to raise the PH even higher! Please help before things start dying :uhoh2:

I don't think it likely that with two part and alk at 8 dKH that the pH 8.6 is correct. I'd recalibrate again, maybe even with new buffers. A few weeks is not often enough for calibration when something appears off, and kits are not very useful.

If aeration raised the pH more, then you certainly have measurement error. There is simply no uncertainty about what aeration will do at 8 dKH and pH 8.6. :)

You are not using new artificial rocks made of cement, are you?