High PH...

[recoiljpr]

Interesting issue I have going on with my tank folks. All of my corals and fish are doing just fine, good growth, getting good color, etc. Through my Brightwells thread I have been monitoring my parameters every 3 days and documenting them.

Today, I purchased a controller from a fellow maast member to automate at least the temp and ph monitoring. Much to my suprise, after having the monitor sit in my tank for about an hour, the PH reading was at 8.77. Now, using Hagen test kit, the color "looked" like 8.3. At this point I know one of the two readings is wrong. I took my ph probe and placed in in straight RO/DI water for one hour. The reading on the probe was 7.05. Granted, I don't know the exact ph of my ro/di water but to me that sounds fairly accurate. I then tested it using the Hagen kit and I couldn't even tell the color.

Right now, I don't have reason to doubt the probe untill I can double check the ph readings at a LFS. I can't think of anything I am doing that would cause such a boost in ph. I am dosing two part, but in controlled measuered dosages. I do know overdosing alk of a 2 part can cause a ph shift, but I don't "believe" that is the problem. I don't drip kalk, or add baking soda, etc. I know that CO2 has a ph lowering effect, but I don't have a good way of testing to see if I do have low CO2. I run my skimmer 24/7.

I am going to lay off dosing my 2 part for a few days to see if my PH corrects itself. Thats something simple I can test. If it does, then I know either something is wrong with the 2-part or I am misreading something on the directions.

I know I can add plain soda water or vinegar to lower my PH for the short term. But, i'd rather try and pinpoint the cause instead of trying to just react. I know my tank is doing ok with the PH it's at now, so I don't think I need to take any immediate measures.

Assuming for now the PH probe is right and I do have excessively high PH does anyone have any ideas or insight as to the possible cause?

[kkiel02]

If you wanna try another test kit you could use mine. Just me me know.

[Ping]

You might need to calibrate or replace the probe. They calibrate in a low and high solution.

[Squiers007]

I would definately look into calibrating the pH meter. Having used them a lot in chemistry and biology labs they are notorious for changing there baselines especially if it is not a very expensive meter. The only way to accurately calibrate a pH meter is with pH standards, never use RODI as the pH can vary from day to day. Even if your meter is calibrated correctly at present, I would still look into buying the standards so that if you run into issues in the future you can easily re-calibrate it.

[Bill S]

As noted above, you need to purchase calibration fluids.

[Paul28]

you need to calibrate the probe, has the probe ever been dryed out if the little glass ball thing ever drys out you have to calibrate it also do you plug it into the wall or is it ran on battery, if its on battery when the batterry starts to get low it wil show high ph and off the wall ph lvls also is it a controler that controls 2 power outlets or is it a monitor that just shows lvls of ph and thats it .. does any pet stores in SA sell the calibrate solotion 7 & 10 im kinda in need too hehe both my controlers have not been cal in over a year so i know im due

[SABOB]

I got 7.0 and 10 pH calibration solution at Aquarium Designs.Had to wait a week or so for the 10.0,Jason had to order it.

[recoiljpr]

It's a controller, so no batteries. I ordered some calibration fluid so it should be here in a few days. The probe was kept wet (It's a lab grade PH probe), it never dried out. If it is a calibration issue why did it give me what seems to be a correct reading when dipped in RO/DI water?

[Bill S]

RO/DI water is only 7.0 as an average... Concentrations of dissolved gas (such as CO2) can certainly change it quite a bit.

In any case, you've only calibrated to the low end of the range - which is kind of "easy". You have, in essence, "zeroed" the controller. Now you have to adjust the high end of the range.

In any case, the probes don't last forever - in saltwater, a couple of years is the expected life. Lab grade won't last any longer. The thing about a pH meter is that it will allow you to keep track of your pH - even if it's not quite accurate - it's repeatable. Just compare it with a good test kit, and go from there.

[CoryDude]

++ on the calibration. Judging from your normal parameters on your brightwell thread, that's probably the logical reason for the high reading. Get a 7.0 and 10.0, as suggested.

[Bill S]

In addition... I'd never make a big pH adjustment based off of a meter. I'd double check it with a test kit of known accuracy.

[Crazyeyes]

I think reefs2you has some calibration solution.

[H2Ochem]

In addition... I'd never make a big pH adjustment based off of a meter. I'd double check it with a test kit of known accuracy.

If properly calibrated a meter is the single most accurate method to measure pH. Hands down. No reagent kit will come close.