My new tank experience managing CO2 and pH

[captainbeardly]

Very cool, great idea, thanks for sharing! I've already created that exact type of air pump housing out of a smalll rubbermaid style bin for my pond air pump that runs through the winter. I think I'd want to come up with something to contain the aeration though, like the skimmer does, as I don't want salt spray all over. Did you do anything to contain your bubbles?

With my air stone in my overflow section of my sump the water flow takes it enough where it disperses the bubbles and doesn’t really create anymore splash then the overflow pipe itself been running like this for a week now with no issues

 

[IKD]

I've tried it. Pulling outside air through my CO2 scrubber had a slight reduced effect on pH and consumed media faster than recirculating the air.

I had a positive effect of having the CO2 scrubber in between the outside line and skimmer. That said, I live in FL and humidity is not an issue for the media. I actually have the media outside.

 

[fryman]

I had a positive effect of having the CO2 scrubber in between the outside line and skimmer. That said, I live in FL and humidity is not an issue for the media. I actually have the media outside.

Just to clarify, it did still increase pH, just not as well as using a recirculating design.

Outside air is relatively low in CO2, but will still introduce some additional CO2 and thus is not as efficient as recirculating. However using outside air also introduces oxygen, which may be desireable.

 

[IKD]

Just to clarify, it did still increase pH, just not as well as using a recirculating design.

Outside air is relatively low in CO2, but will still introduce some additional CO2 and thus is not as efficient as recirculating. However using outside air also introduces oxygen, which may be desireable.

Ah, thanks for clarifying. I also recommend folks calibrate their pH probes. I was fighting to raise a peak pH of 8.0 for months and in reality it was 8.35 (after calibration).

I was thinking of doing an experiment of just the outside line with and without the scrubber (sitting outside) to see if there is much of a difference

 

[thewedge]

Great shares, all. Thanks. I just ran a line from the scrubber intake into the hole in my skimmer lid. The float switch is in the external skimmate collector so it was available. Has gotten me a .2 increase so far, which is good. I think switching to soda ash for alk dosing will get me the rest of the way to 8.3. I'll probably do that in the next couple weeks. Also going to calibrate the probe. I did so when I got it back in Sept and the probe was spot on at the time.

 

[Randy Holmes-Farley]

Just to clarify, it did still increase pH, just not as well as using a recirculating design.

Outside air is relatively low in CO2, but will still introduce some additional CO2 and thus is not as efficient as recirculating. However using outside air also introduces oxygen, which may be desireable.

Recirculating is not necessarily going to always be more efficient than using outside air, and IMO, it is not an optimal use of a skimmer because it eliminates O2 exchange.

But as to efficiency, if your skimmer is good enough at gas exchange then the air returning to the scrubber from recirc could possibly be higher in CO2 than outside air (though not higher than the indoor air, except possibly at night).

 

[Morpheosz]

Great shares, all. Thanks. I just ran a line from the scrubber intake into the hole in my skimmer lid. The float switch is in the external skimmate collector so it was available. Has gotten me a .2 increase so far, which is good. I think switching to soda ash for alk dosing will get me the rest of the way to 8.3. I'll probably do that in the next couple weeks. Also going to calibrate the probe. I did so when I got it back in Sept and the probe was spot on at the time.

That's great!

You may already know this, but for anyone who doesn't know (I didn't the first time I calibrated my probe), the calibration is very temp sensitive so make sure you float your calibration packet to get it up to 78. I didn't the first time as my tank had yet to be heated when I set it up and when I finally figured out that I needed to do it at 78, it calibrated ~0.2 points lower.

 

[IKD]

Ah, thanks for clarifying. I also recommend folks calibrate their pH probes. I was fighting to raise a peak pH of 8.0 for months and in reality it was 8.35 (after calibration).

I was thinking of doing an experiment of just the outside line with and without the scrubber (sitting outside) to see if there is much of a difference

Did my small experiment. Even comes with a picture!

I did one week with skimmer line going outside, then attached a CO2 reactor which was also outside. You see an improvement of about ~.12 (last few nights on the graph) with the CO2 reactor in place.

 

[Morpheosz]

Did my small experiment. Even comes with a picture!

I did one week with skimmer line going outside, then attached a CO2 reactor which was also outside. You see an improvement of about ~.12 (last few nights on the graph) with the CO2 reactor in place.

That's a solid result! Have you tried recirculating out of curiosity to see what that does in your setup? Also curious what your outside temps are where you live.

 

[Dennis Cartier]

I’m doing a PH experiment as well. I tried the airline from outside to the intake of the scrubber and had the same negative effect on PH. So I reconfigured my scrubber into a recirculating scrubber and my PH stayed at 8.0-8.15 according to my Hydros monitor and double checked with a good old manual tester. So I was thinking why not pump even more fresh air into and see if it changes? So I picked up a cheap air pump, a small plastic container, tubing, and an air stone. Placed the air pump outside in the small plastic container with holes drilled in the side and not the top in case it rains or anything. Ran the air line tubing with the air stone to my sump and it boosted my PH to 8.25-8.28. So I think the combination of outside air and a CO2 scrubber is really a good way to go!

Along these lines, I had a small DC pump with a needle wheel and venturi on hand. I had bought a couple of them intending to see if they could be used for aeration. When I was having a low PH issue, I hooked it up to my outside airline and tossed it into my fuge barrel. Did wonders for the PH of the tank, not so much for the health of the fuge.

I plan to do this again in the future and have sourced a Sicce pump with a needle wheel and will make a venturi for it.

 

[MoorishIdol814]

Recirculating is not necessarily going to always be more efficient than using outside air, and IMO, it is not an optimal use of a skimmer because it eliminates O2 exchange.

But as to efficiency, if your skimmer is good enough at gas exchange then the air returning to the scrubber from recirc could possibly be higher in CO2 than outside air (though not higher than the indoor air, except possibly at night).

With all of this talk about recirculating, I figured I would chime in. The attached was after media change, using recirculation with a valve to adjust and pull some ambient air as well. Question though.... I've been getting some negative feedback regarding the recirculating method due to possibly introducing something bad back into the water?? Does anyone have any information on that? I've not seemed to have any negative outcome from it...

 

[Morpheosz]

With all of this talk about recirculating, I figured I would chime in. The attached was after media change, using recirculation with a valve to adjust and pull some ambient air as well. Question though.... I've been getting some negative feedback regarding the recirculating method due to possibly introducing something bad back into the water?? Does anyone have any information on that? I've not seemed to have any negative outcome from it...

That likely refers to the potential of your skimmer going crazy (for any reason skimmers occasionally go crazy) and filling up the cup and sucking the skimmate up into the CO2 media, dissolving a bunch of it and pulling it into your tank via the air intake. I think a best practice is to have a float valve or some other shut off on your skimmer to prevent that. I installed a float valve in the lid of my skimmer for that reason (as well as to alert me when my skimmer cup is full).

 

[MoorishIdol814]

That likely refers to the potential of your skimmer going crazy (for any reason skimmers occasionally go crazy) and filling up the cup and sucking the skimmate up into the CO2 media, dissolving a bunch of it and pulling it into your tank via the air intake. I think a best practice is to have a float valve or some other shut off on your skimmer to prevent that. I installed a float valve in the lid of my skimmer for that reason (as well as to alert me when my skimmer cup is full).

Thank you for the info. I certainly understand the concerns with the CO2 media and skimmate. I have a reef octopus skimmate locker with float and a failsafe in line for any moisture concerns. From what I read, it seemed like there could have been "something else" that could cause issues. I have not a clue what that could be if we are talking all precautions are in place..... if you are really worried about it, I've seen a collection cannister added in line on the recirculation line coming back to the scrubber.

 

[Morpheosz]

Thank you for the info. I certainly understand the concerns with the CO2 media and skimmate. I have a reef octopus skimmate locker with float and a failsafe in line for any moisture concerns. From what I read, it seemed like there could have been "something else" that could cause issues. I have not a clue what that could be if we are talking all precautions are in place..... if you are really worried about it, I've seen a collection cannister added in line on the recirculation line coming back to the scrubber.

I'm not worried about it, the setup has been working great for me for weeks and my skimmer reliably shuts off when full. Additionally, my sump and skimmer are in the basement of my house and the CO2 scrubber is mounted about 5' above my skimmer on the wall so I don't think it would even be possible for the skimmate to be lifted up the tube that far with the relatively small amount of suction the air intake creates.

 

[Randy Holmes-Farley]

h.... I've been getting some negative feedback regarding the recirculating method due to possibly introducing something bad back into the water?? Does anyone have any information on that? I've not seemed to have any negative outcome from it...

Should be nothing bad added back, but my concern is lack of oxygenation.

 

[Morpheosz]

Should be nothing bad added back, but my concern is lack of oxygenation.

I'm not too concerned in my case as I have a ton of surface area between my sump and tank with a lot of turnover and surface agitation. If anything, it's probably the reason my CO2 scrubber solution is not raising my pH much above 8.2. I would assume that most tanks with good flow would be able to get adequate oxygenation without a skimmer otherwise most nano tanks would have a problem.

 

[Randy Holmes-Farley]

I'm not too concerned in my case as I have a ton of surface area between my sump and tank with a lot of turnover and surface agitation. If anything, it's probably the reason my CO2 scrubber solution is not raising my pH much above 8.2. I would assume that most tanks with good flow would be able to get adequate oxygenation without a skimmer otherwise most nano tanks would have a problem.

Most people assume this, but I do not know whether it is true or not.

perfect aeration is rarely achieved in a reef tank since almost all show a day to night pH swing (which doesn't exist when aeration is perfect).

 

[MoorishIdol814]

Should be nothing bad added back, but my concern is lack of oxygenation.

Thank you Randy. I bubble scrub at night to help fight this, pretty good surface agitation, 2x MP40, 2x MP10for movement, 2 return lines for surface, and adding a UV line to the DT which will help a bit also. 180Gal.

 

[Randy Holmes-Farley]

Thank you Randy. I bubble scrub at night to help fight this, pretty good surface agitation, 2x MP40, 2x MP10for movement, 2 return lines for surface, and adding a UV line to the DT which will help a bit also. 180Gal.

OK, those things will help.

 

[Morpheosz]

Thank you Randy. I bubble scrub at night to help fight this, pretty good surface agitation, 2x MP40, 2x MP10for movement, 2 return lines for surface, and adding a UV line to the DT which will help a bit also. 180Gal.

What is "bubble scrub"?