Low ish PH??

[ReelRednekReefer]

My PH has always been low, every tank Ive had. It's always between 7.7 and 7.9. Usually ( 90% of the time) closer to 7.7. Right after heavy WC I'll see an 8.0 but within an hour back to 7.7. I have tested with calibrated ph meter, drop test kit and strips at the LFS...all same results. I've always used RODI ( 0tds) water and reef crystals salt. 10-12hr light cycle. This was the case in Florida, now the same in Texas. I've done the aeration test many times to check for excess co2 but never a change. I know steady is more important but the low level is something Id like to resolve in this tank. Any help would be appreciated.

 

[TheClark]

Great article here to determine the cause. http://www.reefkeeping.com/issues/2004-09/rhf/

 

[Randy Holmes-Farley]

Unless your pH measurement is off, CO2 in the air would be the explanation.

Did you do the aeration test with outside sir, and for how long?

 

[glb]

Unless your pH measurement is off, CO2 in the air would be the explanation.

Did you do the aeration test with outside sir, and for how long?

Randy helped me fix the same problem with a combination of kalk and more aeration. He's got great advice. Good luck!

 

[ReelRednekReefer]

I took a cup ( 8 oz ) of tank water ( 7.77 meter and 7.8 drop test ) out on the porch. Stirred vigorously throughout the depth of the container. Enough to create bubbles that lasted 1-2 seconds for about 30 seconds. Did this several times over the coarse of 10 minutes in different vials, then tested with meter and drop test after each swirl. All readings were approx 7.8 on meter and drop tests.

 

[ReelRednekReefer]

Ahhh. I see i was misinformed as how to administer the aeration test. Will perform correctly in the daylight hours. This is a new tank and may be part of this issue, but I had same numbers in 3 other tanks in a different house in a different state!

 

[Randy Holmes-Farley]

One half of the test needs to be done with outside air.

I describe it here:

Low pH: Causes and Cures by Randy Holmes-Farley - Reefkeeping.com

 

[ReelRednekReefer]

What ratio do I mix the borax and RODI to calibrate my meter?

 

[Randy Holmes-Farley]

By itself, is not suitable for calibrating a pH meter. It can be used to check for proper calibration. This article describes it:

Aquarium Frontiers Biochemistry of Aquaria

from Craig's article:

"Because 1 quart = 946.4 milliliters (ml), if we use a pint of water and add a half teaspoon of borax to it, we should have a pH standard solution with 2 grams of borax per 473 ml or 4.3 grams of borax per liter. This is within about 10 percent of the standard borax pH calibration solution, and because of the weak dependence of pH on concentration, it is close enough for our purposes. So, you should be able to use everyday kitchen measuring equipment to make this solution."

 

[ReelRednekReefer]

Ok. So the borax is a way of checking the calibration to make sure its not WAY off? How often should I check it?

I ordered some more calibration powder- 4.01 and 6.86. Will arrive Wednesday and then I'll be back to post my readings as soon as I can conduct all the tests.

 

[Randy Holmes-Farley]

Can your meter use pH 6.86? Mine can, but many cannot and can use only exactly pH 7.

How often depends on how fast it seems to drift. Start At a week, and go up from there. It might last months.

 

[ReelRednekReefer]

I ordered the same exact stuff it came with.

K. That's what I was thinking but didn't know.

 

[Randy Holmes-Farley]

OK sounds good.

What meter is it?

 

[ReelRednekReefer]

Etekcity from Amazon. Any good?

 

[Randy Holmes-Farley]

Etekcity from Amazon. Any good?

I've not actually heard of it before.

 

[ReelRednekReefer]

It had really good reviews. If I wanted a probe to constantly monitor PH, what specific qualities would I want? Or is there a go to brand? Best value?

 

[Randy Holmes-Farley]

In terms of the meter itself, two or more point calibration is important.

For the probe, when they are separate, I discuss what to look for here:

Aquarium Chemistry: Measuring pH with a Meter ? Advanced Aquarist | Aquarist Magazine and Blog

from it:
Selection of Combination pH Electrodes
There are hundreds of different types and styles of pH electrodes. These vary in size, composition (glass or plastic sides, typically), shape, the nature of the glass membrane (even non-glass materials can be used), how that membrane is separated from the internal filling solution, (that is, single vs. double junction), whether the internal fluids are sealed or refillable, and a variety of other issues.


For most reef aquarists, the exact nature of the pH electrode doesn't much matter. Nearly all can give suitable pH readings. Here is my opinion about what is most important to look for:


Selecting an epoxy body electrode instead of a glass body electrode will make it less likely that you will break it by accident. The glass bulb on the tip is still very fragile (I've broken many), but the bulb can be protected by a plastic shield to reduce the chance of breakage.


If you intend on measuring pH directly in the aquarium or sump (rather than in a cup of water removed from the aquarium), then expect to occasionally get the whole electrode wet (by accident). If it is a refillable type which has a hole for adding more filling solution (usually KCl), then you might get aquarium water into the electrode. That can severely degrade performance by messing up the reference electrode. So selecting a sealed electrode may be a better choice.


Some folks argue that a double junction electrode is preferable, and that is likely true. Without going into the design details, a double junction electrode makes it much less likely that there will be any exchange of ions between the aquarium and the filling solution through the glass bulb. This option may be especially important if you are using an internal reference electrode other than Ag/AgCl. For example, if it is a calomel reference electrode, it contains mercury. It is desirable to keep mercury salts out of the aquarium due to its toxicity, so a double junction is likely preferable in that case. Likewise, it is desirable to keep sodium and other seawater ions from entering the reference electrode, and a double junction prevents that to a much greater extent than a single junction. That aspect is more important if you leave the electrode in the aquarium water than if you put in into a storage solution after every use. In general, it is likely better to have a double junction than a single junction, but it may not result in appreciably better measurements.


There are other attributes of certain electrodes that may make them more useful in laboratories, and hence justify prices that easily range to more than $350 for the electrode alone. There is not likely any significant advantage in using such electrodes for reef aquaria, however. Do not be worried about claims that you need a special electrode for high pH or high sodium environments. That is true for the most accurate measurements at high pH and high salinity, but aquarium water will be OK with a standard electrode, and even brief measurements at high pH (like limewater) will be fine.

 

[beaslbob]

Just out of curiosity are you measuring PH just before light out?
I would add macro algaes and watch the pH increase but IMHO it does need to be measured just before lights out on the macros.
my .02

 

[ReelRednekReefer]

No set time. I've checked just after lights on, midday, and just before lights off. Typically I'll get 7.7 in the a.m., and 7.9 in the evening. I sometimes would get a 8.0 after WC, but fresh mixed SW never reads more than 8.1.

 

[ReelRednekReefer]

Alright just finished testing. Results are as follows:

With lights off for 12 hours ~7.8
With lights on for 12 hours ~8.0

Tank water, no lights with aerator outside for 1 hr : ~8.2
Tank water , no lights with aerator inside for 1 fr : ~7.8

So obviosly excess CO2 is the issue.... Now what?

Running a line outside isn't an option. So do I buffer with Kalwasser or do I build a DIY CO2 scrubber?