bringing down co2

[Jason Donohoe]

I suspect I have a high CO2 problem in my tank as the pH sits around 8.0 (this morning 7.9) despite an alk of 3.5 - 4 and using unsaturated limewater for all top offs. I always measure the pH within 1-2 hours of lights on in the morning.

A few questions:

There is a lot of air mixing with the tank water from the overflow (very bubbly bubble tower both from the main overflow and from the refugium into the sump). Would adding an airstone help (assuming the co2 is not high in the room air)?

Would leaving the lights on the refugium 24/7 help. I've just started growing chaeto and the lights are set off cycle.

A little off topic, but can you saturate unsaturated settled limewater? I was thinking that I could boost the alk and maybe alter the pH slightly by using fully saturated limewater but I already have 10 gallons mixed up and settled with 4 tsp/5 gallons.

Any thoughts greatly appreciated.

 

[jenglish]

I can't say this is your prob but co2 rises in the home during winter when the house is sealed up. I have seen people actually run a airline from their window to their skimmer venturi.

 

[Jason Donohoe]

I was thinking of drilling a hole straight through the wall behind the tank and running a line to an airstone. If I do it when my wife isn't home she doesn't have to know. And if she doesn't know she won't need to kill me.

 

[MCsaxmaster]

To saturate your limewater you can just mix in more Ca(OH)2. I'd mix in more calcium hydroxide to the limewater you've prepared and would use saturated limewater for topoff. That's usually the most effective way to raise tank pH.

 

[Jason Donohoe]

Chris,

You don't think trying to correct the underlying problem of CO2 would be better? Or do you think it would be both easier and more effective to use the fully saturated limewater?

 

[MCsaxmaster]

<a href=showthread.php?s=&postid=13960505#post13960505 target=_blank>Originally posted</a> by jason.donohoe
Chris,

You don't think trying to correct the underlying problem of CO2 would be better? Or do you think it would be both easier and more effective to use the fully saturated limewater?

I think using saturated limewater will be easier and the more effective of the two methods. Of course, doing both would be more effective than either individually at raising pH. Using saturated limewater alone may or may not be sufficient to get the pH you want.

p.s. Very cool avatar

 

[Jason Donohoe]

Thanks for the help. I'll try the saturated limewater first.

 

[MCsaxmaster]

<a href=showthread.php?s=&postid=13960545#post13960545 target=_blank>Originally posted</a> by jason.donohoe
Thanks for the help. I'll try the saturated limewater first.

Doing so also has the benefit of not makeing the wife want to kill you

 

[Jason Donohoe]

Very true. Alive and pH 8.1 is better than dead and 8.3!

 

[MCsaxmaster]

<a href=showthread.php?s=&postid=13960693#post13960693 target=_blank>Originally posted</a> by jason.donohoe
Very true. Alive and pH 8.1 is better than dead and 8.3!

Well now you're just splitting hairs :lol:

 

[Boomer]

Jason

One of the things do, if one can, is to run 2 small duck works from the tank to the outside. One duck, on one side of the hood back, pulls in outside air via a fan and the other duck on the other side of the hood, via a fan, sucks in hood air and blows it back outside. This means that the tank is always getting fresh outside air and moving it across the top of the water from one end to the other and will stop this CO2 pH issue.

 

[Jason Donohoe]

Hey Boomer,

Thanks for the idea but I think that would involve more construction than I am up for. The tank is actually on the third floor of the house and it would be very difficult to do any of the finishing required on the outside (short of renting a cherry picker/lift).

 

[Jason Donohoe]

Boomer,

Doesn't that set up air condition your whole house? I've been to northern Minnesota in February, it wasn't all that warm.

 

[David Grigor]

It can work but could make your heater go into overdrive. Living in MN, it just isn't an option for me and those in our club that do try it sometimes find that it doesn't make as big a difference as they hoped.

First off, 7.9-8.0 in the morning hours is not an issue. However, if you are looking to increase it. I have found it quite effective to instead of topoff off 24/7. To schedule it to topoff only at night when PH would be at the lowest ( must use a dosing pump, not a water level based topoff as it would add too much too fast, need to spread it out evenly throughout the night ). It helps considerably to raise the levels because your tank doesn't spend the first few hours when the lights are on trying to raise the PH. Since doing the many years ago, my tank PH is actually at it's lowest in the evening rather than the morning. Now my PH never goes below 8.3. If it is below 8.3 that usually means the Kalkwasser hoses are clogged or partially clogged.

Running macro algae 24/7 may help raise some but you still will have the swing.

 

[Jason Donohoe]

David,

Unfortunately my top off involves me and a jug without any pumps to be seen. I use a one gallon jug with a needle hole in the corner that drips in over a fews hours. I will try setting it up last thing at night rather than in the morning so the lights out period starts with a higher pH.

 

[MCsaxmaster]

Jason,

For what it's worth, I do think it's a reasonable idea to try to increase tank pH, but I'm not sure it's really worth it to lose sleep over what you're seeing. Running higher than NSW alkalinity may be enough to offset any negative effects of low pH on calcification in many if not all of the organisms in the tank. pH in that range is also not outside of what seems perfectly tolerable by reef organisms.

I'd try using saturated kalk first, and see where you get with that. A pH range of 8.0 (low) to 8.2 (high) might be achievable. Combined with higher than NSW alkalinity, I probably wouldn't worry too much about fiddling with that. That's pretty darn good, and certainly functional.

 

[Boomer]

Jason

In places like MN you have to preheat the incoming air, with a small blower heater or an duck in-line heating rod. The big issue for most is the duck work itself i.e., 3 inches in Dia. or so for both ducks.

I also agree your pH as of now is not an issue and is fine.

David

It works great. It is not to solve "tank" CO2 pH issues it is to solve "high room air" CO2 issues that bring down the tank pH . If the tank has its own pH issues, of low pH, from excessive food or poor conditions it is not going to do that much.

 

[GeoffM1968]

was thinking of drilling a hole straight through the wall behind the tank and running a line to an airstone. If I do it when my wife isn't home she doesn't have to know. And if she doesn't know she won't need to kill me.

This is exactly what I did when I realized after our "cold" spell the a/c unit has not run in couple weeks and increased CO2 in the house. I ran an airline to the skimmer which had minimal impact for me and then ran a second line to an air pump I install outside house. I had to drill a hole behind the tank for the airlines and finished it off with a face plate in case my wife ever figured out what I did.

For me Kalkwasser alone did not resolve issue. I was in different shape than you as I was running 8.0 to 8.1 pH with A/C running. When a/c stopped after couple weeks I was then in range of 7.6 to 7.8. The combination of Kalk and external air, I am now back up to 7.85 - 7.98 after a week.