co2 scrubber

[sbazain]

question if I close half way the inlet to the scrubber will the media last longer or it won't make a difference and does the amount of media has to do also in how fast it runs out I added 375ml and its half way after a week

 

[Randy Holmes-Farley Verified Community Expert]

You mean limit the air flow?

The media will last longer but the pH effect may be smaller and skimming may be impacted negatively.

 

[sbazain]

yes , it went up from 7.8 to 8.2 8.3 in 5 days used half of the media already but like I said I only have 375ml in the reactor

 

[Duberz]

That's the problem I'm having. I installed the brs co2 scrubber and it did exactly what I wanted. I went from 7.7 to 8.3 in a few days. Problem is the media which isn't cheap only lasts a few days to a week. I might try the recirculating method which supposedly makes the media last much longer.

 

[Jon's Reef]

Recirculating does wonders. Two fold effect:
Keeps it moist, but not wet
Recycled air is prescrubbed

 

[Randy Holmes-Farley Verified Community Expert]

I think recirculating is potentially a bad concept because it gives up one of the important benefits of a skimmer: oxygenation at night.

 

[ShaneWedge]

Why don't you make a Co2 scrubber that fits to your airline of your skimmer? Raises Ph slower with less stress on your fish.

 

[Randy Holmes-Farley Verified Community Expert]

Why don't you make a Co2 scrubber that fits to your airline of your skimmer? Raises Ph slower with less stress on your fish.

What do you mean "fits"?

This sounds like how they are typically used.

 

[Jon's Reef]

I think recirculating is potentially a bad concept because it gives up one of the important benefits of a skimmer: oxygenation at night.

Why would it reduce oxygenation at night?

 

[Randy Holmes-Farley Verified Community Expert]

Why would it reduce oxygenation at night?

It is somewhat disappointing to me that folks like BRS who are pushing this practice appear to have not considered all of the ramifications of recirculating the skimmer air before recommending it. They should at least mention the theoretical concern, if not measure it, before advising folks to do it.

Skimmers have been shown to oxygenate the water of reef tanks, which often become less than saturated with O2 at night. By aerating with air that has normal oxygen levels, the skimmer can raise those levels. Eric Borneman showed this in his O2 studies.

If a skimmer is no longer getting fresh air, but only air that is already in O2 equilibrium with the water (as recirculating air will be) it can no longer increase the O2 level in the water.

Is this a big problem in most tanks? Probably not. But it is a drawback that is being ignored.

 

[Jon's Reef]

but only air that is already in O2 equilibrium with the water

Is this really an equilibrium process (ex. tank with air above it) or a kinetically limited diffusion process? Air has ~210k ppm oxygen, where as seawater saturation is only ~7 ppm. The Borneman study showed saturation achieved from a hypoxic system in ~20 min.

As long as you do not hermetically seal the setup, the minor amount of air exchange in the skimmer cup should be sufficient.

 

[Randy Holmes-Farley Verified Community Expert]

Is this really an equilibrium process (ex. tank with air above it) or a kinetically limited diffusion process? Air has ~210k ppm oxygen, where as seawater saturation is only ~7 ppm. The Borneman study showed saturation achieved from a hypoxic system in ~20 min.

As long as you do not hermetically seal the setup, the minor amount of air exchange in the skimmer cup should be sufficient.

i don't see any reason to think oxygen leaking into a skimmer cup will do much for aeration.

Eric found that skimmers alone, even when used as intended, while they helped, did not bring the bigger tanks into saturation at night. It is much harder than many folks think to completely exchange gases. If it was easy, pH would not vary day to night in reef tanks.

Certainly gas exchange is a kinetic process, and tanks often are not at equilibrium in either O2 or CO2.

My concern is if you remove a large part of the oxygenation capability of a skimmer by recirculating the air, the tank may go to lower O2 values at night (maybe higher during the day, whether that is good or bad, I do not know).

 

[Jon's Reef]

i don't see any reason to think oxygen leaking into a skimmer cup will do much for aeration.

The skimmer cup mixing does not provide water aeration, rather an opportunity for the recirculated and open air to replenish the oxygen. This is what makes it an open versus closed system. In a closed system it could certainly strip the oxygen reducing the diffusion potential.

If the air starts at 210k ppm oxygen, goes through the skimmer (gas exchange etc) then comes out the top...we will likely not see substantial oxygen depletion of the recirculated air in a short period of time that is not compensated by the small fresh air exchange in the skimmer cup (saturation being 7 ppm... with fraction of a ppm exchange rates).

 

[sbazain]

Why don't you make a Co2 scrubber that fits to your airline of your skimmer? Raises Ph slower with less stress on your fish.

Already added a scrubber ph is at 8.2 now actually it was at 7.7 with a api tester now I used a ph meter and its at 8.0 so actually the api test was off by 3

 

[ShaneWedge]

i don't see any reason to think oxygen leaking into a skimmer cup will do much for aeration.

Eric found that skimmers alone, even when used as intended, while they helped, did not bring the bigger tanks into saturation at night. It is much harder than many folks think to completely exchange gases. If it was easy, pH would not vary day to night in reef tanks.

Certainly gas exchange is a kinetic process, and tanks often are not at equilibrium in either O2 or CO2.

My concern is if you remove a large part of the oxygenation capability of a skimmer by recirculating the air, the tank may go to lower O2 values at night (maybe higher during the day, whether that is good or bad, I do not know).

Also if you have watched a few episodes of Mr. Saltwater Tank, He also talks about running and air line to the outside of your house for fresh O2. Otherwise you can just put some medical grade "soda lime" in a bottle and make your own CO2 scrubber.

 

[sbazain]

so my last batch of media lasted 5 days this batch lasted 2 days what could be the reason nothing in the house has changed I know its not a good idea to reticulate but am going to have to go that rout

 

[Randy Holmes-Farley Verified Community Expert]

The skimmer cup mixing does not provide water aeration, rather an opportunity for the recirculated and open air to replenish the oxygen. This is what makes it an open versus closed system. In a closed system it could certainly strip the oxygen reducing the diffusion potential.

If the air starts at 210k ppm oxygen, goes through the skimmer (gas exchange etc) then comes out the top...we will likely not see substantial oxygen depletion of the recirculated air in a short period of time that is not compensated by the small fresh air exchange in the skimmer cup (saturation being 7 ppm... with fraction of a ppm exchange rates).

I hear what you are claiming, but I don’t know whether it is correct.

 

[reefluvrr]

If a skimmer is no longer getting fresh air, but only air that is already in O2 equilibrium with the water (as recirculating air will be) it can no longer increase the O2 level in the water.

Randy, I plumb an air pump with an air hose teed to my recirculating CO2 scrubber to bring in some fresh air outside my sump area. Could this be a solution to lower Oxygen levels at night?

 

[Randy Holmes-Farley Verified Community Expert]

Randy, I plumb an air pump with an air hose teed to my recirculating CO2 scrubber to bring in some fresh air outside my sump area. Could this be a solution to lower Oxygen levels at night?

Addition of fresh air into the loop certainly help, yes.

 

[SPS2020]

My skimmer often gets too active to consider recirculating the air from that source. Too much of a chance of sucking up some skimmate.

I've been pondering adding another inline canister (the same configuration as the scrubber) which contains a water source and maybe a piece of foam to help wick the moisture. So, outside air would first go through the "moisture chamber" and then into the scrubber.