PH 7.88-7.98, can not increase

[Sullivmw]

I am having a consistent problem with low PH, staying in the range of 7.88-7.98. I test with 2 different pinpoint monitors that are calibrated monthly.

I dose daily with Kalk, but ALK is now at 11dkh and calcium is near 480ppm

After reading several articles it seems that I have a CO2 problem in the house. The house is 3 years old and seems fairly airtight. I notice if I open the window for a day, soon after the PH will go up to 8.1+. Once the windows are closed, the PH will slowly fall back down. In the fall I had the windows open for weeks at a time and the PH would stay right at 8.2 - 8.3.

The problem is I live in the South where opening a window in the middle of summer is not an option. Is there anything else that I can try ?

[Randy Holmes-Farley]

You can possibly bring in fresh air in an airline to a skimmer air inlet.

Are you replacing all evaporated water with saturated limewater (2 or more teaspoons lime per gallon)? No vinegar, right?

Are you adding any other alkalinity additives?

[Sullivmw]

Randy -

I originally was using the ESV 2 part (original), the readings were about the same as they are now. When using it, if I dropped the dosages, then the Alk would go back to 11, but PH would go to around 7.79-7.9,

I am now using only Kalk water, about 2 teaspoons per gallon, I did try 1 teaspoon per gallon, it did not seem to make any changes.

I have not used any other supplement for Kalk for about 5 months. All evaporated water with Kalk, and no vinegar.

Water changes are every 3-4 weeks, approx 15%

[Randy Holmes-Farley]

How are you measuring pH?

Some test kits read low, especially when old.

[Sullivmw]

I have been using 2 different pinpoint PH monitors. I calibrate them monthly and they seem acurate. I have compared them with friends and they are about right on.

Also I have used them with only the batteries and had all power equipment off just to make sure interference was not an issue.

[Randy Holmes-Farley]

Other than fresh air and limewater, the options are rather limited.

1. You can add more lime as a slurry.

2. As long as the pH is below 8.1, you can up the alkalinity even further without causing increased abiotic precipitation of CaCO3. You could do that with the lime slurry, or B-ionic.

Just to be sure, you could check the pH meters in borax:

Borax pH Calibration
http://web.archive.org/web/20021015005420/www.animalnetwork.com/fish2/aqfm/2000/feb/bio/default.asp

If you cook with gas, you might use the vent whenever cooking (if you have one). That will help reduce ambient CO2 levels.