CO2 scrubber disappointing results

[ca1ore]

In the skimmer this contact area (if the air contain its 20 % oxygen) is much, much, much, much greater than an area you can create with waves on the surface.

You sure about that ….. and lest it be less than completely obvious, I am not. Does the total surface area of the bubbles in the skimmer exceed that of constantly turning over the various surfaces of a reef system (including the agitation created by the drains)? I've not tried to do the math ….. probably couldn't even if I wanted to. What I did do, some years ago, was to measure my tank with a DO meter with and without the skimmer and there was no material difference (neither during light hours nor dark). Further, since the 'main' purpose of the skimmer is to encourage proteins to adhere to the bubble/water interface, I also wonder how effective those bubbles actually are at diffusing oxygen if they are quickly getting 'gummed up'. I do not therefore find it necessary to rely on my skimmer for oxygenation, thus using recirculated air …. which was my original point. I do appreciate, however, that not all systems may be so designed ….. thus perhaps your point.

 

[SCReef'n]

How on earth do people keep fish and corals alive without skimmers in their system?

 

[X-37B]

In AZ with very low humidity levels the water at the bottom dries up quickly.

The unit I used had holes in the bottom of the container and it sat above the water in the sump which kept it moist and it never dried out.

 

[KenO]

The unit I used had holes in the bottom of the container and it sat above the water in the sump which kept it moist and it never dried out.

Smart idea.

 

[coastal_kid]

A couple of thoughts. Using recirculating air for a skimmer is fine as long as you have adequate circulation in your tank. If you rely on the skimmer to be an important oxygenator (generally a bad system design IME) then obviously recirculating the air is NOT a good idea. Whether a fresh air line or CO scrubbing works is a function of CO2 balance between the water and the air. If you scrub the skimmer air of CO2, but your system is 'marinating' in high CO2 house air then the effect is likely to be marginal.

Thanks. I would say I have excellent air exchange. I have a large, open sump. The display tank is 180 gallons and is open. Between the return nozzles and the two MP40s, the water at the top of the tank roils.

I live in Arizona and the temperature is over 110 this time of year.
That, combined with the dust, means we keep our windows closed.
It also means we stay indoors.
And there is a pandemic that keeps us indoors more than usual.
And plants don't grow well in this house.
It is possible that our indoor CO2 levels are high.

 

[coastal_kid]

Having run a CO2 scrubber in AZ if you don’t provide it with moist air it will dry out. You could add a wye fitting and use some valves to pull moist air from the skimmer and inside air to provide fresh O2. I ended up pulling fresh moist air from my ATS.

Now with that said, is there a way to try running some tubing to the outside to pull in outside air? I’m in N Scottsdale and my outside air co2 measures 395-400ppm. My inside air co2 prior to installing a whole house air exchanger was in the 900+ppm range. With the air exchanger the co2 of the inside air is now below 500ppm.

I no longer run a CO2 scrubber, I found pulling in outside air worked better and is a whole lot less expensive.

Thanks. It is just not practical for me to run a line outside at this time.
If I ever have a custom-designed house, you can be sure there will be a water pipe, drain, and access to outside air. Who knows? I might even build a closet for the machinery.

 

[coastal_kid]

The unit I used had holes in the bottom of the container and it sat above the water in the sump which kept it moist and it never dried out.

An advantage of pulling air out of the skimmer cup is that is air is extremely moist. There is plenty of condensation in the tube leading from the skimmer cup to the intake on the CO2 scrubber.

 

[Lasse]

You sure about that ….. and lest it be less than completely obvious, I am not. Does the total surface area of the bubbles in the skimmer exceed that of constantly turning over the various surfaces of a reef system (including the agitation created by the drains)? I've not tried to do the math ….. probably couldn't even if I wanted to. What I did do, some years ago, was to measure my tank with a DO meter with and without the skimmer and there was no material difference (neither during light hours nor dark). Further, since the 'main' purpose of the skimmer is to encourage proteins to adhere to the bubble/water interface, I also wonder how effective those bubbles actually are at diffusing oxygen if they are quickly getting 'gummed up'. I do not therefore find it necessary to rely on my skimmer for oxygenation, thus using recirculated air …. which was my original point. I do appreciate, however, that not all systems may be so designed ….. thus perhaps your point.

http://reefkeeping.com/issues/2005-06/eb/index.php

http://reefkeeping.com/issues/2005-07/eb/index.php

http://reefkeeping.com/issues/2005-08/eb/index.php

This investigation was done around 2005. Today skimmers are more powerful - produce smaller bubbles, suck more air and have higher retention time. Boreman did not found the same effect from skimmers in large aquarium but found them very effective in order to maintain at least 80 % saturation in smaller aquarium (75 gallon) With larger and better skimmers for large system (that we have today) However the best source of oxygen into the system is photosynthesis but skimmers are important in order not to get a very low reading during night even for system at least up to 300 G IMO

Sincerely Lasse

 

[ca1ore]

Yeah, I’m familiar with those articles .... having read them back when they originally appeared. They were actually the impetus for me to do my own, somewhat amateurish tests. I have found some of his conclusions to be valid, others less so. I use high display turnover and reverse lit ATS and refigium ..... so the skimmer simply does not function materially as aerator.

 

[proxy001]

I am with OP. No difference. Media is hardly turning purple ( tried 2 different media). IMHO it will only work is CO2 is high. If CO2 is within normal won't do much. Also it means the skimmer pulls a lot of air, Im thinking if skimmer too low in sump, might have some effect. The only I keep my Ph in the 7.9-8.1 range is ALK in the 9.5-9.8 range... Im giving up on Ph !!

 

[Lasse]

I use high display turnover and reverse lit ATS and refigium

It means that you have a decent internal oxygen production 24/24. The photosynthesis is the most important (and fastest) source for a high oxygen production. Below there is the oxygen curve for an experimental tank - around 1100 L (around 240 gallon) with light on during 05:45-18:15. Reverse lighting - refugium - 19:00-07:00. It seems like the oxygen content is around 1 hour delayed compared to change in the lighting - often with a dip a hour after both light is zero (18:45 - 19:00)

This system swings mostly between 105% and 90% - mostly - IMO - because of a rather good reversed refugium- IME - the normal swing with only a skimmer will be down to around 80 %. The date´s is 3 months ahead - but it is an experimental tank adapted to the seasons near the equator.

Before this tank I use skimmers very rarely - I was a fan of skimmerless tanks without a skimmer. However - once - in skimmerless tank, crowded with soft corals - you could not see a stone for all corals - all my fishes died during one night. The only reason why was - IMO - oxygen depletion. After this I have used skimmers in all my tanks - sometimes without a skimmer cup - mainly for the oxygenation of the tank. In tanks heavily populated with corals - there is a huge consumption of oxygen during no photosynthetic action hours.

Oxygen is one - IMO - most important parameters for a good working reef. Often forgotten - but still important. One of my dreams is that i would be able to get 24/24 oxygen meter in my aquarium and have it to manage my skimmer. I could get it tomorrow - but it will cost me around $ 550 ...... But sooner or later - it will come

A refugium is also a huge consumer of CO2 - below I have attached the pH for the last week, you can see how fast the pH answer to the different photosynthetic systems in the whole setup. During day - pH is driven up to around 8.5 and it goes fast down from DT light intensity peak and start to climb up during the refugium light period (constant). After that period there is a dip again until the intensity of the DT´s light is enough. The system use Triton Core 7 - therefore the rather high total pH (their alkalinity part is probably Na2CO3 - it rise the pH much more than NaHCO3 . )

​

@coastal_kid Sorry for the off topic but - a good reversed refugium could be a better tool compared with a scrubber

Sincerely Lasse

 

[BrianReefer]

I just addressed this same issue in my SPS 120g tank. I run a Bill Wann ACR so my PH was on the very low side, 7.65-7.85. I ran an outside line that feeds into the top of a jar filled with water, then another line also drilled into that jar that feeds my CO2 scrubber (that all keeps air moist), then from scrubbe to skimmer. Set this up a week ago, the CO2 media is still only 1/5 used up and my PH is now averaging 7.9-8.2.

 

[ca1ore]

One of my dreams is that i would be able to get 24/24 oxygen meter in my aquarium and have it to manage my skimmer. I could get it tomorrow - but it will cost me around $ 550 ...... But sooner or later - it will come

When my handheld DO meter failed, I toyed with getting the Apex PM3 but just couldn't justify the cost … it's about the only apex module I don't have.

 

[Clownfishy]

It means that you have a decent internal oxygen production 24/24. The photosynthesis is the most important (and fastest) source for a high oxygen production. Below there is the oxygen curve for an experimental tank - around 1100 L (around 240 gallon) with light on during 05:45-18:15. Reverse lighting - refugium - 19:00-07:00. It seems like the oxygen content is around 1 hour delayed compared to change in the lighting - often with a dip a hour after both light is zero (18:45 - 19:00)

This system swings mostly between 105% and 90% - mostly - IMO - because of a rather good reversed refugium- IME - the normal swing with only a skimmer will be down to around 80 %. The date´s is 3 months ahead - but it is an experimental tank adapted to the seasons near the equator.

Before this tank I use skimmers very rarely - I was a fan of skimmerless tanks without a skimmer. However - once - in skimmerless tank, crowded with soft corals - you could not see a stone for all corals - all my fishes died during one night. The only reason why was - IMO - oxygen depletion. After this I have used skimmers in all my tanks - sometimes without a skimmer cup - mainly for the oxygenation of the tank. In tanks heavily populated with corals - there is a huge consumption of oxygen during no photosynthetic action hours.

Oxygen is one - IMO - most important parameters for a good working reef. Often forgotten - but still important. One of my dreams is that i would be able to get 24/24 oxygen meter in my aquarium and have it to manage my skimmer. I could get it tomorrow - but it will cost me around $ 550 ...... But sooner or later - it will come

A refugium is also a huge consumer of CO2 - below I have attached the pH for the last week, you can see how fast the pH answer to the different photosynthetic systems in the whole setup. During day - pH is driven up to around 8.5 and it goes fast down from DT light intensity peak and start to climb up during the refugium light period (constant). After that period there is a dip again until the intensity of the DT´s light is enough. The system use Triton Core 7 - therefore the rather high total pH (their alkalinity part is probably Na2CO3 - it rise the pH much more than NaHCO3 . )

​

@coastal_kid Sorry for the off topic but - a good reversed refugium could be a better tool compared with a scrubber

Sincerely Lasse

Can you give us an idea of how big your refugium is and what you had in there? I ask as I am trying to prevent the drop of pH at night and although the C02 scrubber it stripping out C02 at night (obviously!), as you know, it will not stop the drop. I was thinking of adding an Algae Reactor to try and prevent the drop but I am not sure this alone will do much? Looking at your graph, I suspect to prevent the pH drop completely at night, we would need to run a refugium with the similar amount of corals and as algae as we do in our main aquarium!

 

[14 foot reef]

To be honest - when I first saw the ideas of recirculation the skimmer air I thought that it was the worst idea for a long time. One of the most important issues for a skimmer is to oxygenate the water. This construction will not help with the oxygenation of the water at all

Sincerely Lasse

LAsse,
I really trust and respect your input on this. Which raises a huge red flag on a skimmer purchase I was thinking about. I wont HiJack this thread, if you don't mind I will send you a message.

 

[Lasse]

Can you give us an idea of how big your refugium is and what you had in there? I ask as I am trying to prevent the drop of pH at night and although the C02 scrubber it stripping out C02 at night (obviously!), as you know, it will not stop the drop. I was thinking of adding an Algae Reactor to try and prevent the drop but I am not sure this alone will do much? Looking at your graph, I suspect to prevent the pH drop completely at night, we would need to run a refugium with the similar amount of corals and as algae as we do in our main aquarium!

You got a PM - enough of hijacking now

Sincerely Lasse

 

[coastal_kid]

I just addressed this same issue in my SPS 120g tank. I run a Bill Wann ACR so my PH was on the very low side, 7.65-7.85. I ran an outside line that feeds into the top of a jar filled with water, then another line also drilled into that jar that feeds my CO2 scrubber (that all keeps air moist), then from scrubbe to skimmer. Set this up a week ago, the CO2 media is still only 1/5 used up and my PH is now averaging 7.9-8.2.

So your setup is:

outside_air --> water_jar --> CO2_scrubber --> skimmer_intake

That bumped your pH approx 0.3.

 

[Reesj]

While on the topic, can I pick the brain of soem of you guys.
Can I put the small air line tube about 3 meters off and still get proper oxigen through it to the skimmer?
I'm a bit worried if the distance of air line tube of 2-3 meters might not draw air properly..

 

[coastal_kid]

While on the topic, can I pick the brain of soem of you guys.
Can I put the small air line tube about 3 meters off and still get proper oxigen through it to the skimmer?
I'm a bit worried if the distance of air line tube of 2-3 meters might not draw air properly..

That's hard to predict. Try an experiment. Get 3 meters of airline, hook it to the intake of skimmer, and observe the results. Do the bubbles rise to the same level as before?

 

[ReefHomieJon]

Whoa, in a day? You should never increase more than 0.5dkh per week. If you have sps you will likely kill them.

All my sps I’ve had since tiny frags. I manually dose all my major and minor elements. When I test and alk gets low I’ll increase alk by 1.4 dkh in a day. That is what Red Sea said was the limit in their dosing manual. I was new and I didn’t no otherwise. Been doing that since I’ve had sps(like 10 months) and they’ve done nothing but grow like maniacs. Ain’t nobody killin sps with a little alk jump lol. I’ve learned to dose a lol each day based on consumption for “stability” reasons but even then it’s drinking .4 a day technically that’s a .4 swing per day right?