Save CO2 scrubber media life by recirculating air? | Reef FAQs

randyBRS

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Hey Reefers!

Huge shoutout to @Velcro and @JDowns for inspiring this episode!

Does recirculating your CO2 scrubber save media? It just might...and thanks to those reefing pioneers who are paving the way in testing this theory, we're getting some solid info that it can actually work. :)

 

Atti2de

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C806F806-86FF-4E9F-A1D7-FBE515FBD34B.jpeg I’ve been reading up on this and I’m going to give it whirl. I was wondering since my sump is covered with lids that I might be about to pull from my sump instead of drilling a hole in my skimmer lid. No worries about my skimmer overflowing then.
 

Kengar

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Hmmmm...... interesting concept. I wonder, though, whether airline hoses leading from majority (if not all) of the holes in the skimmer lid back to the inlet to the scrubber would impede airflow out of the skimmer, thereby suppressing rise and expansion of bubbles in the chamber and somewhat defeating the purpose of the skimmer. Also, I suspect that additional tubes all hanging off of the lid would make it a PITA to handle the lid (take it off, set it aside) when pulling off the collection cup to clean it and the neck of the skimmer.

Taking suggestion from one of the earlier BRS videos, I set up two Apex-controlled 24V solenoid valves to regulate flow, one to permit flow through the scrubber and other to prevent flow directly into skimmer when pH falls to 8.09 or below (and reverse operation when it rises back to 8.10 or above). See below. So at least I'm not wasting media by running flow through it 24/7, and by affirmatively closing the solenoid in front of the scrubber when pH rises, I prevent "passive" flow through the scrubber due to aspiration when air otherwise flows most significantly through the other line (path of least resistance) when the non-scrubbed solenoid is opened. (By the way, note that I've got the solenoids suspended by those metal straps away from the wood mounting beam; they get HOT!)

IMG_6174.jpg
 

Atti2de

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Hmmmm...... interesting concept. I wonder, though, whether airline hoses leading from majority (if not all) of the holes in the skimmer lid back to the inlet to the scrubber would impede airflow out of the skimmer, thereby suppressing rise and expansion of bubbles in the chamber and somewhat defeating the purpose of the skimmer. Also, I suspect that additional tubes all hanging off of the lid would make it a PITA to handle the lid (take it off, set it aside) when pulling off the collection cup to clean it and the neck of the skimmer.

Taking suggestion from one of the earlier BRS videos, I set up two Apex-controlled 24V solenoid valves to regulate flow, one to permit flow through the scrubber and other to prevent flow directly into skimmer when pH falls to 8.09 or below (and reverse operation when it rises back to 8.10 or above). See below. So at least I'm not wasting media by running flow through it 24/7, and by affirmatively closing the solenoid in front of the scrubber when pH rises, I prevent "passive" flow through the scrubber due to aspiration when air otherwise flows most significantly through the other line (path of least resistance) when the non-scrubbed solenoid is opened. (By the way, note that I've got the solenoids suspended by those metal straps away from the wood mounting beam; they get HOT!)

IMG_6174.jpg

How often are you changing out media?
 

mjkusa

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How about adding a liquid collector cup before the line is returned to the scrubber. Basically a line out from skimmer enters the top of the sealed collector cup and a line out from the top of the collector cup to the scrubber. This way, only dry air is being sent back to the scrubber and any gunk that makes it out of the skimmer is collected on the bottom of the collector cup.
 
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Ohashimz

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I use co2 scrubber for years. I was never able to revive it...
 

fattiremike

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I use a pint Mason jar for a catch-can. I tapped into the lid of the skimmer with a John Guest fitting and ran that to the pint Mason jar. Then, from the Mason jar to the C02 scrubber. Co2 scrubber to the air inlet on the skimmer. I put John Guest fittings on all threaded connections. I drilled a couple of appropriate sized holes to press-fit the hard airline in the lid. I have to empty the jar every week or so. It keeps the scrubber from filling up with water.
 

Kengar

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I use co2 scrubber for years. I was never able to revive it...
By "revive," do you mean regenerate the media so that it can be used again? If so, that's not what they are referring to in this thread. They are talking about recirculating the air coming out of the skimmer back to the input to the scrubber, since that air will have already been scrubbed before it was injected into skimmer. Idea is to reduce scrubbing load on the media by not putting completely fresh, unscrubbed air through it.
 

Kengar

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How often are you changing out media?
Just set it up last week, so don't know what sort of consumption rate this will have.

Frankly, I'm thinking about pulling the current skimmer and using an external/recirculating skimmer in its place and filling that entire chamber with macro, so that I have a "yuuuuuge" refugium running counter to DT light cycle. Maybe THAT would stabilize the pH.......
 

rvitko

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Hi, Roger with Tunze here, so I was sent here by a customer I spoke to at RAP NY. Some years back, a competitor of ours did something we were intrigued by as it simplified skimmer design and reduced cost, they essentially used the skimmer cup as a silencer and took the air from the skimmer cup. We bought one and tested it and found it performed poorly. We had a hunch that the decomposing skimmate created gasses or possibly just the high humidity of the skim mate and popping bubbles was affecting skimming. We tested this by A) taking one of our skimmers and rigging it to draw from the cup and B) taking the competitors skimmer and rigging it to a conventional silencer to take in fresh air. The results were fairly convincing that this is a bad idea. We still don't know why, but by our testing, taking air from the skimmer cup seems to impede skimmer performance. From some cursory research we strongly suspect that methane and sulfur compounds reduce the surface attraction of the bubbles, these large molecules do not lend themselves in the same way to being charged by the ionic soup of saltwater and picking up organic matter as just plain O2 and N2. FWIW, said competitor likely noted the same as they no longer do it this way and we know of no manufacturer who takes air from the skimmer cup though we kept this study a secret as we had no interest in helping someone else improve their products. I would be very interested to know if anyone who has done this has seen less overall skimming as a result.
 

Kengar

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Entz

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Hmmmm...... interesting concept. I wonder, though, whether airline hoses leading from majority (if not all) of the holes in the skimmer lid back to the inlet to the scrubber would impede airflow out of the skimmer, thereby suppressing rise and expansion of bubbles in the chamber and somewhat defeating the purpose of the skimmer. Also, I suspect that additional tubes all hanging off of the lid would make it a PITA to handle the lid (take it off, set it aside) when pulling off the collection cup to clean it and the neck of the skimmer.
If this works I wonder if there will be a market for replacement "Lids" that have a fitting pre-added so as to not mess with the skimmer or better something that is a hybrid where you have the normal lid and normal holes and then have a cap over top that will let air out but also let air be taken in and the "mixture" can be adjusted to find the optimum skim-mate production and re-circulation potential.
 

Velcro

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If this works I wonder if there will be a market for replacement "Lids" that have a fitting pre-added so as to not mess with the skimmer or better something that is a hybrid where you have the normal lid and normal holes and then have a cap over top that will let air out but also let air be taken in and the "mixture" can be adjusted to find the optimum skim-mate production and re-circulation potential.
Sounds like a job for avast marine..
 

KenO

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Besides a skimmer I have an ATS. If I pull air from the skimmer cup or ATS I get the same results with my pH levels. The ATS gives me humid air like the skimmer cup without the gunk.
 

KenO

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So is it the lower CO2 levels or the humidity or a combination of the two that helps to raise pH higher? I know adding more humidity to the media makes it last longer.
 

hart24601

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Hi, Roger with Tunze here, so I was sent here by a customer I spoke to at RAP NY. Some years back, a competitor of ours did something we were intrigued by as it simplified skimmer design and reduced cost, they essentially used the skimmer cup as a silencer and took the air from the skimmer cup. We bought one and tested it and found it performed poorly. We had a hunch that the decomposing skimmate created gasses or possibly just the high humidity of the skim mate and popping bubbles was affecting skimming. We tested this by A) taking one of our skimmers and rigging it to draw from the cup and B) taking the competitors skimmer and rigging it to a conventional silencer to take in fresh air. The results were fairly convincing that this is a bad idea. We still don't know why, but by our testing, taking air from the skimmer cup seems to impede skimmer performance. From some cursory research we strongly suspect that methane and sulfur compounds reduce the surface attraction of the bubbles, these large molecules do not lend themselves in the same way to being charged by the ionic soup of saltwater and picking up organic matter as just plain O2 and N2. FWIW, said competitor likely noted the same as they no longer do it this way and we know of no manufacturer who takes air from the skimmer cup though we kept this study a secret as we had no interest in helping someone else improve their products. I would be very interested to know if anyone who has done this has seen less overall skimming as a result.
This is really valuable information and thank you for posting it. I wonder if doing a diy job putting some activated carbon between the two in an intermediate container would help.
 

JDowns

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Hi, Roger with Tunze here, so I was sent here by a customer I spoke to at RAP NY. Some years back, a competitor of ours did something we were intrigued by as it simplified skimmer design and reduced cost, they essentially used the skimmer cup as a silencer and took the air from the skimmer cup. We bought one and tested it and found it performed poorly. We had a hunch that the decomposing skimmate created gasses or possibly just the high humidity of the skim mate and popping bubbles was affecting skimming. We tested this by A) taking one of our skimmers and rigging it to draw from the cup and B) taking the competitors skimmer and rigging it to a conventional silencer to take in fresh air. The results were fairly convincing that this is a bad idea. We still don't know why, but by our testing, taking air from the skimmer cup seems to impede skimmer performance. From some cursory research we strongly suspect that methane and sulfur compounds reduce the surface attraction of the bubbles, these large molecules do not lend themselves in the same way to being charged by the ionic soup of saltwater and picking up organic matter as just plain O2 and N2. FWIW, said competitor likely noted the same as they no longer do it this way and we know of no manufacturer who takes air from the skimmer cup though we kept this study a secret as we had no interest in helping someone else improve their products. I would be very interested to know if anyone who has done this has seen less overall skimming as a result.
I can't say that I've seen a reduction in skimming as a result. Although my lid does have two holes, and I've vented the line to reduce condensation and excess humidity.
 

Michael Hull

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I’m finding that my Red Sea RSK skimmer has flatter bubbles now that I’m recirculating. I seem to have raised pH but reduced the effectiveness of pulling skimmate over the top of the cup. Maybe I need to split the draw 50/50?
 

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