Basement Tank vs High Ambient CO2 Levels.

[aarbutina]

Hey @Randy Holmes-Farley, I would love to bounce something off of you. I recently moved it to a new home and set up my tank in the basement.

During the past couple of months, I have been battling a depressed pH in my tank. Depending on a number of different variable the pH seems to vary any where between 7.8 and 8.2 but to achieve the peak of that range I need to pull quiet a few different levers.

The crux of my problem is significantly elevated CO2 levels in the basement, which are around 1500 ppm when the window are closed and can get down to around 900 ppm when the window are open all day long.

Last weekend I was able to run a fresh air line out side for my skimmer in hopes for being able to keep the window closed. My desire would be not to need to keep opening the window every day as it lets in a good bit of humidity to the basement which is not ideal.

Unfortunately, with the windows closed (ie high CO2 levels inside) the outside air line does not seem to be boosting the pH to a level even comparable to what it was when I just opened the window. Yesterday, my pH maxed out at 8.07 and was down to 7.87 this morning.

Am I doomed to needing to open the window every morning to get this pH up (until I can get an air exchanger installed)?

I also run Kalk (from a Kalk reactor) on my system, but it doesn’t seem to offer much benefit with regard to pH. My question here is, is it possible that while my top off water is sitting, that it is becoming saturated with the high CO2 from the basement air, and the I am dumping that into the tank as top off and I to the Kalk reactor, creating calcium carbonate and negating and ph benefits it may provide? If that is the case should I aerate my top off water in an attempt to purge the CO2? Would I need to do this in a different room when the ambient CO2 levels aren’t as high? Once back in the basement how long would it take for the CO2 to start to saturate the top off water again?

 

[arking_mark]

Two pieces of info:

1. You'll need skimmer aeration that outcompetes your tank aeration from pumps and powerheads. My tank setup required a skimmer 3x the size recommended for the tank. I use CO2 scrubbed air.
2. When I recency had to replace my heating and air conditioning unit, I added an air exchanger. It had very limited impact.

 

[Randy Holmes-Farley]

Do you know what sources of CO2 might be in the basement? Do people hang out there?

 

[aarbutina]

Do you know what sources of CO2 might be in the basement? Do people hang out there?

My thought, though it may be incorrect, that it just collects down there from the rest of the house. It is new construction and is closed up pretty tight. No one really hangs out down there besides me when I am working on the tank.

when I measured the CO2 upstairs one day it was approximately the same.

 

[Randy Holmes-Farley]

My thought, though it may be incorrect, that it just collects down there from the rest of the house. It is new construction and is closed up pretty tight. No one really hangs out down there besides me when I am working on the tank.

when I measured the CO2 upstairs one day it was approximately the same.

Yes, that's likely.

Once mixed in, CO2 doesn't preferentially settle. But high concentrations in the upstairs air might move downward.

Some CO2 will enter the water sitting in the basement, but not nearly as much as would enter higher pH systems such as kalkwasser or salt water.