Guys I hate to add another thread about PH.

[caferacermike]

Salty I had heard the same thing about DI making monitors go screwy, I was afraid of that. I do add makeup water to the sump. Mayeb when the frsh DI passed over the end it messed up the calibration. How do I avoid this in the future if that turns out to be the problem? Turn it off for an hour while adding water? I pulled the unit from the sump, wiped it clean with a toothbrush (not mine, hehe) and tried other areas of the tank. When pulled from the water it ranged out the numbers, the second it was back in the tank, 9.02.

Ok ok so most think it is the montior and not the water.


But just what if it was my water? What could cause it to rise that high? What does it mean if it is that high? I've heard that PH over 8.0 causes ammonia to become lethal. My corals all look excellent, fish look good. Only my wrasse is acting weird, but that is also his personality could be a fluke with that guy.

[Richard]

The only things I can think of that can cause PH not to correspond to your alkilinity are...

Elevated CO2 levels in which case ph will always be lower.

Elevated borate levels.

[matt]

D.I. is not going to push your tank from 8.3 to 9.0. If your ph was really that high, there would probably be all sorts of other indications, as that's way out of the normal range for most marine animals. It's your probe.

[GaryP]

OK, I hate to do it, but its chemistry lesson time.

1. pH probes work by passing an electrical current across the probe. This current is in the form of potassium ions passing through the glass bulb on the end of the electrode. Without any metals in RO/DI water you don't get a very good current. RO/DI basically doesn't have a pH because there are no other ions, such as buffers, present to effect the pH.

2. Most pH electrodes are not designed for continuous use the way that most reefers use them. When I worked in a lab, we stored them in a potassium chloride solution or pH 7 buffer between uses. Over time, the potassium leaches out of the electrode and it stops working. The electrode is semi-permeable (the glass bulb) and over time the ionic balance in the electrode gets "unbalanced" and it's no longer accurate. You can try soaking the electrode in a KCl (Morton Lite Salt) solution or pH 7 calibration standard for a few days and see if that helps, but I think its probably dead. We routinely replaced our electrodes once a year and always had a spare available if we needed it. The way to check an electrode is to calibrate it, and then go back later and re-check it to make sure its holding its calibration.

3. Another thing that happens is that bacteria and other critters grow on the surface of the electrode. This also affects the permeability of the electrode and shortens its life span.

4. We calibrated our pH meters every day. Of course we were looking for more accuracy then most reefers care about, down to about .01 pH units. We even kept a log book that showed how, when, and by who the meter was calibrated by. Even in the case of a reefer, they do require frequent and routine calibration.

5. The only way you could get to pH 9 is if you were dumping a lot of base into your tank. I had to work hard to keep my pH up to 8.6 by dripping Kalk everyday when I had an outbreak of dinoflagellates. The natural trend of pH in a tank is downwards, not upwards, unless you have something really freaky happening. This is the result of CO2 production and depletion of the buffers by bacterial produced organic acids.

6. The only other thing I could think might be happening is that you got a bad batch of salt that had to much sodium carbonate or borate in it. Try testing your water change water.

7. Unfortunately we have a tendency to look at the most recent change in how we manage our systems as the obvious cause of some negative impact. The reality is that our systems are pretty dynamic and things are always happening. Sometimes we just need to step back and look at the bigger picture. We also have a tendecy to think of our analytical tools as fool proof. As with any electronic device, they all fail eventually. The same can be true of the wet chemistry kits we use. Reagents go bad, get wet from humidity, etc. On top of that is the factor of human error. When things don't add up, sometimes the best thing we can do is just step back and ask ourselves if the problem may be ourselves, at least in how we are interpreting what these tools are telling us. Whenever you get weird results, the best thing to do is often to just step back and ask yourself if this makes sense.