ph is at 8.7

arashsheikhpoor · May 23, 2015

So my ph has been climbing recently.. I just calibrated my rkl and it still says 8.7

I also checked with the api and it is a purple to red color.

Calcium is at 490 and alk is around 9.7 and salinity is 1.025

I have been dosing vinegar the last 5 days at 1.5 ml a day.. is this increasing the ph and do you guys thing I should stop (it was for my nitrates that were at 15ppm)

Reefing Madness · May 24, 2015

1.5mls isn't very much, and shouldn't change your PH unless we are talking about a 3g tank.
Get your powerheads pointed at the water surface more, or inject some fresh air.

arashsheikhpoor · May 24, 2015

Will try and report back tomorrow.

Randy Holmes-Farley · May 24, 2015

IMO, it is very unlikely the pH is really 8.7 unless you are using a lot of limewater (kalkwasser).

pH does not naturally get above normal in a reef aquarium, and if it is, more aeration will solve the problem.

This has more:

http://reefkeeping.com/issues/2005-03/rhf/index.htm

arashsheikhpoor · May 25, 2015

So I'm thinking it must be a faulty ph probe. I did a 15 gallon WC on my 75g and the ph now is at 8.79

Was 8.69 before the WC a few hours ago.

Randy Holmes-Farley · May 25, 2015

How did you calibrate it?

arashsheikhpoor · May 25, 2015

I went to the calibration menu on the reefkeeper. First it asked for the ph 7 solution and I let it sit there for about 20 min until the number next to the 7.00 was stable then did the same for the ph 10 solution.

Randy Holmes-Farley · May 25, 2015

Try measuring the pH in those solutions now. If it doesn't read both correctly, it needs recalibration.

arashsheikhpoor · May 26, 2015

Thanks randy. I appreciate all the help.. I will do that tonight when I get home

anikamal · May 27, 2015

Have you increased your flow recently? I had the same issue. I just got a gyre and had it running 24/7, it was increasing oxygenation, which in turn increases pH

arashsheikhpoor · May 27, 2015

Hey I did increase flow but I thought increased oxygenation would decrease ph?

arashsheikhpoor · May 27, 2015

Icalibrated last night and it is at 8.8 at the end of my light cycle

anikamal · May 27, 2015

arashsheikhpoor said:
Hey I did increase flow but I thought increased oxygenation would decrease ph?

Other way around. It's the same process in humans, oxygen deprivation leads to acidosis so when you increased your flow you increased pH as well. Turn down the flow to test it

arashsheikhpoor · May 27, 2015

That's funny. I initially thought that but had a few different people tell me the opposite so I thought it might work differently in the tank..anyways thanks.. I'm gonna try to lower the flow and see what happens

Randy Holmes-Farley · May 27, 2015

Don't bother. Lowering the flow will not lower the pH in your situation.

Oxygenation doesn't impact pH, but driving CO2 into or out of a tank will impact pH. Normal aeration will tend to drive the pH either up or down toward whatever pH that batch of salt water will have in relation to your home air.

If the pH is already on the high side for some reason, more aeration will lower the pH.

Did you try measuring the calibration solutions?

pH 8.8 in an aerated reef tank is a measurement error for sure unless the alkalinity is super high or you just overdosed on limewater (kalkwasser).

arashsheikhpoor · May 27, 2015

the ph is correct. I measured the calibration fluid and they came back correctly.

And my alk is at 8.9 as of yesterday

It was originally at 10.1 when I noticed the high ph.

Randy Holmes-Farley · May 27, 2015

I just do not believe that the pH is correct. Perhaps the calibration fluids are off. I would get new fluids. As they age, the pH 10 fluids drop in pH, causing readings to read false high. Other effects can cause problems as well, such as contamination.

FWIW, I have literally read hundreds of high pH threads, and they end up being measurement errors unless they are due to an overdose. There's no mechanism for the pH to get that high 24/7 in a reedf tank with aeration.

One way to check it is to aerate a cup of the water for an hour or so using outdoor air. The pH should move to about pH 8.2 at that alkalinity.

You can also check the meter for proper operation in a borax solution.

scardall · May 27, 2015

try using a ph test kit instead or take a water sample to a LFS. I'm willing to bet your probe is going bad.

arashsheikhpoor · May 27, 2015

I'll go get a small solution kit and re calibrate tonight. I have a api kit and to be honest the color is purple but it has a reddish tint which I had not seen till recently.