Stale Air - high CO2 Level? Answers?

[rabeiler]

I have a general question regarding CO2 levels in the air around the tank.

I found this forum very helpful in researching my problem. Here are the details and my general question.

I have my 120g reef built into the wall with a nice maintenance room behind it with counter space, sink, shelving, etc. The room is about 550 sq ft. Since setting up the tank, I had problems with low PH and this forum and the information helped me to determine that the ambient CO2 levels were too high to allow enough release of CO2 from the tank. PH levels were dipping below 8 at night and never getting higher than 8.1 even though I use Kalkwasser for top off.

I tried aerorating the tank more - no luck.

I move the air pumps to a seperate room in the basement (were my tank is) - no luck.

I put an exhaust fan in the tank to suck air outside and pull from the rest of the house - better, but still not very good.

I left all doors open throughout the basement to get some air moving throughout the entire basement - this worked. Proved to me that I had a CO2 issue in the room.

I can't leave all of the doors open all of the time (too noisy). My current solution involves a blower fan that pulls air from the outside into the tank room at the same time the exhaust fan is running. Both fans move around 100 CFM, so I run them on a timer for 10 minutes each hour. I may try to reduce this or change the times for less during the day and greater at night when the CO2 generation in the tank is at its highest.

So much for new construction. I never would have anticipated this problem in the design of the room.

My general questions are these - does anyone see any potential flaws in my logic? Do you think that 10/50 cycle is okay, or should I run 5/30 to keep the air more consistent?

I will keep updating this thread with my results and would appreciate your comments.

Thanks,
Ross

[Doug1]

Hi Ross a hi CO2 level in the tank room will keep pH suppressed. I recall a few years back when people were running airline outside to feed skimmers, air exchange will help with it, you will prolly have to play with times to get where ya need to be

[tdwyatt]

Originally posted by rabeiler
I have a general question regarding CO2 levels in the air around the tank ... My general questions are these - does anyone see any potential flaws in my logic? Do you think that 10/50 cycle is okay, or should I run 5/30 to keep the air more consistent?

Your thinking on this is good, but you might consider using a skimmer as the means of running air thru just the aquarium. The skimmer will run tremendous amounts of air through your water column, especially if you use a beckett injector-type skimmer. You can run a piece of large-diameter PVC pipe to the outdoors and let the beckett injector pull the air into the system directly, withut exposing the rest of the house to exterior air sources. Using a fan pointed at the surface of the tank will increase your exchange rate. Try increasing surface agitation by having a powerhead just under the surface with the output pointed parallel to the surface. It would be a good idea to pull the air out of the house with an exhaust fan, as most houses are not so "tight" that they will not seep in adequate air for exchange by doing the exhaust alone. Might also consider a refugium/sump with a large population of macroalgae (halimeda, please) running with a 24/7 "lights on" photoperiod.

[rabeiler]

Tom,

Thanks for your suggestions. I do have a skimmer. Red Sea Classic X-Large skimmer. Air pump is located outside of the fish room. I ran a fan in the room as well so that it would move air across the tank. I also had a 3" airstone at the bottom of the tank in the back, center of the tank. None of these seemed to do the trick. I have two maxi jet power heads at each side of the tank that cycle every 6 hours. They are angled down about 15%. I have two smaller flow jets that I am going to install this week and I will keep them parallel to the surface.

I will investigate what a beckett skimmer looks like and how it operates to see if this makes sense as well. Thanks for your suggestions.

Ross

[Spanky]

Ross

Hi, I know you mentioned you're using Kalk, but what is your Alk reading? Are you sure you're keeping it high enough?

A quick and easy way to raise Ph is to use sodium carbonate as your only source of Alk for a while. We have that happen here in the winter when it's necessary to keep the buildings closed.

Monitor your Ph while you do this and when you see that it's holding for a while, you can go back to using Kalk.

Jerel

[tdwyatt]

Originally posted by Spanky
...what is your Alk reading? Are you sure you're keeping it high enough?

A quick and easy way to raise Ph is to use sodium carbonate as your only source of Alk for a while.

I agree with Spanky, if you're doing all the other things, it may be an alkalinity issue, but it wouldn't hurt to go ahead and do the things you've already planned to undertake anyway.

HTH,

[rabeiler]

I have been monitoring alkalinity, ph, ORP, calcium, and the more common bio indicators.

Alkalinity is currently averaging around 3-3.5 meq/l, +/- 0.5. Calcium is averaging around 400, +/- 20.

During the course of the last two weeks I have been monitoring the calcium and alkalinity levels almost daily. Prior to that, I was just monitoring the ph. I was adding a buffer (Reef Buffer by Sea Chem) to bring the ph up. It would go up and then go back down. I did not have any corals in the tank, just some fish and live rock.

That is when I started looking on the web for help with my ph problem and TRT forums where great source of info. I quickly realized I needed to look at the alkalinity levels. Wish I would have studied chemistry more in college, but just focused on electrical engineering.

Anyhow, when I tested the alkalinity, I was shocked to see that it was 6.5 meq/l. I did a couple of 5% water changes, one each day for four days. This lowered the alkalinity to around 4. I also discovered that my calcium level was low (around 300). I used a calcium supplement to bring the calcium levels back in line over the course of a couple of days using a Kent drip doser.

Getting the tank parameters (other than the ph) back in line took a little less than a week. It wasn't until I started addressing the air quality issues (stale air) in the room that I found my ph levels returning to acceptable levels.

Should the alkalinity be higher than 3 or 3.5? According the article that I read on ph, alkalinity, and calcium a 3 or 3.5 reading is good, although a little higher than natural sea water.

Thanks for all your ideas - this is a great forum. I need to get a digital camera so I can post some pics.

[Geoff]

i am battling the exact same problem. i am pretty darn sure that it is a CO2 export issue like Tom has said. i have since uncovered a couple of things and my ph is going back up slowly.

i think your blower idea is a good one. i have a feeling it will just be a matter of trial and error to find the minimum amount of time you can have the blowers on.

quick question: when you opened the door, how long did it take for your tanks ph to go up?

G~

[rabeiler]

quick question: when you opened the door, how long did it take for your tanks ph to go up?

By just opening the door into my tank room and opening up a door that lead to the outside, my ph went from 7.89 to 8.03 in less than 2 hours. Might have actually gone up quicker, but I wasn't checking it in between those time frames.

[rabeiler]

All,

Just wanted to update you on the results that I have been getting and some fine tuning. I picked up a two outlet air pump that allowed me to run an airline hose from the pump inlet to the outside. This allows me to keep the air pump in the fish room, but have it get fresh air from the outside to inject into the Protein Skimmer (Red Sea Berlin Skimmer) and I also have two 3" airstones in the sump where the overflow from the tank enters. The sump in about 7" deep (old 55g tank) so a decent amount of air bubbles develop.

I run the exhaust fan for 15 minutes every hour. I don't run the fan that pulls from the outside into the tank room during the day when the temperature gets to hot which causes the tank room to heat up. My next chore is to find or build something that will monitor the temperature in the fish room and the temperature outside to determine if I want to pull air from the outside or from the house. I want to have something that will hook up to a PC so I can create a program with the logic that I can then feed into my AquaController to signal it to turn on or off the fans. If anyone has any ideas, let me know.

Ross

[Geoff]

what are your results so far?

G~

[rabeiler]

Ph has been ranging from 8.15 to 8.35. The high ranges occur during the later part of the day when the lights have been on for 8+ hours. The low ranges have been overnight and in the early mornings.

I use Kalkwasser to replace evaporation and have a Calcium reactor that injects CO2 when the PH reaches 8.3 and shuts off when the PH falls below 8.2. The Calcium reactor that I have is really crappy. It was something I purchased about 5 years ago when I had a reef setup. I tore the system down when we were selling our house in 1999 and didn't set the system back up until the end of 2002 when I finished off the basement in the new house and built the room to display the tank within my office.

I have just ordered a Nilsen reactor and Calcium reactor from My Reef Creations. Andy has been very helpful in answering my questions and I have received a lot of positive feedback from others that use their equipment.

One other thing that I did was improve the surface skimming. I had a homemade configuration over my two overflow boxes that had holes drilled in them to keep fish out of the overflow boxes. I have since redid these to look like large toothed combs made out of 1/4" plexiglass. They work much better, chop up the water on the way down and there is no cover over the overflow chamber to trap CO2.

Ross

[Xwild]

If you're finding that the CO2 levels in your fishroom are low enough to be surpressing your ph levels that much, I'd think you mite want those fans in the wall just to make the house more liveable anyways.. CO2 in high concentrations ain't the best thing to be breathing in...

I know when I start getting headaches in my apt, first thing I do is open a couple windows (regardless of time of year) and get some fresh air in the place.. That normally gets rid of the headache pretty quick..

[rabeiler]

Rest of the house is not a problem. The tank is in the basement and when I built the room for the fish tank and sump, I did too good of a job of creating a pretty tight room. I was trying to keep the moisture from the tank from getting into the rest of the house. I had no idea that I was going to cause issues with CO2. I wish I knew someone who had a CO2 measurement device for normal air. I have seen some and they are pretty expensive.

[cyberchef]

You might also want to check the rest of the house and make sure that your heating, dryer and hot water heater (provided they are all gas) are venting properly. If your getting a build up of COP2 then it has to be coming from somewhere. You already proved that pulling air from the rest of the house won't solve the problem therefor it would be a good indicator that the CO2 levels in all of the house might be high and therefor it might be an issue to look into more thoroughly.