PH of RO water, adjusting PH and much more...

[blaze422]

Is there a normal PH for RO water? my RO is purchased from reef store....it tests 7.97 on my PH monitor that hasn't been calibrated in the 5 months I've owned it. Can't find my calibration solutions but will have calibration done tomorrow, at store. Reason for the question is that I am dosing Kalkwasser with a Kangaroo pump and my ph has jumped to 8.75 from a 8.15-8.35 previous range in the last 2 weeks... I tried to modify with white vinegar, and got the range back to 8.35 in a week....but this afternoon ( 1 day later) I'm backk at 8.75. If my RO has a high PH to begin with, I'm wondering if I need to be more aggresive with the vinegar. ( I am adding 6oz per gallon of water mix dosed each day.)
I have added a rufegium in the last month asnd have the lights running 24 hrs/day over it...read something about photosynthesis raising PH. A factor?

130 gallon tank
0 nitrates,nitrites, ammonia
Ca++ 400
Alk 12


__________________

[Randy Holmes-Farley]

It is unlikely that the pH of the starting RO water has any real impact on the pH of the limewater, which should be in the mid 12's.

Photosynthesis does raise pH as it consumes CO2.

More aeration will bring the pH down, as long as the alkalinity is not excessively high.

The vinegar is another way to bring down pH. How much vinegar are you using for how much solid lime? That is, you use 6 ounces of vinegar per freshwater gallon, but how much lime? (FWIW, that amount sounds incredibly huge to me; most folks use 10-50 ml per limewater gallon).

This article may help:

Solutions to pH Problems
http://www.advancedaquarist.com/issues/june2002/chem.htm

[jdieck]

blaze:
Just insure your PH readings are real specially if you have not calibrated your monitor fro that long of a time.

[Boomer]

Is there a normal PH for RO water? my RO is purchased from reef store....it tests 7.97 on my

No, not really. It can often be a false reading, same for test kits, as there is not much of anything in the water for the meter or kit to measure. RO/DI water pH is even more useless. However, how it is exposed and where may make a difference, such as CO2 getting in the water would give a more meaningful pH measurement of that water.

[blaze422]

I am an idiot...calibration test indicates that the 8.75 reading is actually 8.0 ouch...I have been trying to lower my PH from 8.75.....adding vinegar and have overshot the appropriate range... I am the poster child for calibration. I realize I haven't screwed things beyond repair, just wanted to remind everyone to trust, but verify!!

[jdieck]

Hey Blaze... Not an idiot just a reefer.... been there, done that:lol:

[Randy Holmes-Farley]

Yes, blaze, you'll find that many of the pH problems in this forum are calibration problems. That is especially true of high pH, unless it is caused by a lot of limewater.

Was 8.0 as low as the pH got, or is it lower? Regardless, the vinegar effect should be transient.

[blaze422]

reef store still has my probe...wanted to make sure it holds it's accuracy. They suspect that it got off by being out of the water....does it seem reasonable that during water changes, the level in the sump gets low and exposes probe to air? They say to keep probe in water at all times... Concerning the PH in my tank, the level was running 8.4-8.1 day/ night for months, then I tried to raise my chroniclly low calium with turbocalcium. After achieving Ca++ of 500 ( too high I realize), I started dosing kalkwasseer. 2 weeks later my PH is running 8.7-8.5 day/night. I thought the kalwasser had caused the PH to skyrocket, it probably was fine all along. If my reckoning is correct, for the past 2 weeks with the addition of vinegar, I was actually running 8.0/7.8.

[gtrestoration]

I know there is no rule for the direction that a pH meter drifts or shifts. But in the fifteen years I've used them mine have ALWAYS drifted up. I can almost tell when I need to calibrate based on the pH meter reading higher than what I would expect. It's almost as though it needs me around to tell it that it's wrong. LOL

Steve U

[jdieck]

Unless the probe gets dry I do not think there is a problem. If you can still calibrate it it shall be OK. To prevent the probe getting dry, if your water changes take more than a couple of minutes and the probe is in a sump then you can install the probe in a block of styrofoam. A block of 1 thick inch and 5" x5" will hold it well, just pock a hole in the center and let it float giving the cable some slack. It will rise and lower with the water level.

[blaze422]

now that I have added a refegium, I will keep the probe there...no subjected to low water levels...

[Randy Holmes-Farley]

They say to keep probe in water at all times...

As mentioned above, if the probe was still wet, that is OK, but if it dried out (even partially dried), that would be a problem. Drying salt water onto it could precipitate CaCO3 onto it that can only be removed with an acid wash.