Downside for co2 scrubber?

[Randy Holmes-Farley]

I totally agree with your explanation. I guess I should of been more specific and said because the the CO2 molecules are homogeneity mixed with the air molecules you will have roughly the same CO2 level in the basement as the rest of the home. Occupation in one area of the home does not necessarily mean the CO2 levels in the other areas are going to be lower. Would that be a better explanation in simple terms?

That could be true, especially in a home with forced air heat or air conditioning. If there is no air forced between rooms, flow of CO2 into rooms where people typically are not will probably make CO2 lower there, but maybe not as low as outside.

 

[Notsolostfish]

That could be true, especially in a home with forced air heat or air conditioning. If there is no air forced between rooms, flow of CO2 into rooms where people typically are not will probably make CO2 lower there, but maybe not as low as outside.

Update on my scrubber went from 7.8 to 8.3

 

[Notsolostfish]

that cap serves as a gateway to connect make your co2 scrubber recirculating.

Does the co2 scrubber have a limit on how hogh it takes co2? My ph was 8.26, 8.28-8.3 but today it barely went over 8.23. The media still white.

 

[Slything]

I hadn't read much of the O2 concerns with recirculating. I just purchased a recirculating lid. I previously have been scrubbing the outside air into skimmer. This has had good results but I was hoping to improve media life with recirculating. Now I'm questioning it after reading comments from randy... at the same time I almost never ran my skimmer in my previous tank, although it wasn't a high-end SPS tank I had plenty of success with softies and lps so I wonder how big this O2 issue is.

 

[Steve2020]

I hadn't read much of the O2 concerns with recirculating. I just purchased a recirculating lid. I previously have been scrubbing the outside air into skimmer. This has had good results but I was hoping to improve media life with recirculating. Now I'm questioning it after reading comments from randy... at the same time I almost never ran my skimmer in my previous tank, although it wasn't a high-end SPS tank I had plenty of success with softies and lps so I wonder how big this O2 issue is.

If you are already bringing in air from the outside ( assuming you mean outside the house ) you can do a similar setup like mine if concerned about O2 levels. I bring in fresh air from the house furnace fresh air return into my scrubber along with the skimmer recirc air. A word of warning, your ph can possibly get a little higher than desired with this setup. I have an electronic ball valve that is controlled by my Profilux to bring in room air to not allow my ph to get above my desired setpoint. I used to run my PH at 8.45 but now run it at 8.38 due to I was thinking the increase in PH was one of the factors of my sand calcifying. Sand was removed and the re-added and so far no calcification noticed. I also have a lot of surface agitation and I also run a " W" Sochting Oxydator.

Recirc and Fresh Air Input to Scrubber


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Electronic Solenoid Valve. Fresh Airline from Fresh Air Return 60ft away.

 

[Slything]

If you are already bringing in air from the outside ( assuming you mean outside the house ) you can do a similar setup like mine if concerned about O2 levels. I bring in fresh air from the house furnace fresh air return into my scrubber along with the skimmer recirc air. A word of warning, your ph can possibly get a little higher than desired with this setup. I have an electronic ball valve that is controlled by my Profilux to bring in room air to not allow my ph to get above my desired setpoint. I used to run my PH at 8.45 but now run it at 8.38 due to I was thinking the increase in PH was one of the factors of my sand calcifying. Sand was removed and the re-added and so far no calcification noticed. I also have a lot of surface agitation and I also run a " W" Sochting Oxydator.

Recirc and Fresh Air Input to Scrubber


f

Electronic Solenoid Valve. Fresh Airline from Fresh Air Return 60ft away.

Thanks for this awesome response!

I think I will be doing the same. So your fresh air joins into the line thats coming from the skimmer lid and then both run through the scrubber before going into skimmer intake ??

Im also going to throw a ball valve on the fresh air line so I can restrict how much is pulled from outside. Not sure if this is necessary but I'm guessing if it was wide open I wouldn't be saving much on media ?

 

[Steve2020]

Thanks for this awesome response!

I think I will be doing the same. So your fresh air joins into the line thats coming from the skimmer lid and then both run through the scrubber before going into skimmer intake ??

Im also going to throw a ball valve on the fresh air line so I can restrict how much is pulled from outside. Not sure if this is necessary but I'm guessing if it was wide open I wouldn't be saving much on media ?

Yes, You are correct to where the fresh air joins as shown in the first photo.
As far as you using a ball valve for the fresh air input, there may be an issue if you plan on adjusting the ball valve periodically. Once you have your skimmer adjusted properly with the ball valve in a set position, if you end up adjusting the ball valve later on, it could affect your skimmer due to a change in air volume input. Then again it might not. Just something to watch out for.
I have run some tests with different configurations on the effects of PH that I just completed the data collection on. I will be posting on a new thread with some GHL Profilux charts tomorrow or in the next few days, and some of the test had different skimmer inputs and I did not have to adjust my skimmer once so you may be ok. I am sure that different skimmers will react differently based on how many liters of air they can pull in and how efficient they are but that's a whole different topic.

 

[Notsolostfish]

Question. My media is starting to get purple color at the bottom but mostly it’s still white. But my PH is dropping. Im surprised as the media havent been fully exhausted. Still plenty of white media

 

[Notsolostfish]

Only drawback to a single pass scrubber is cost.

Using a full recirculating scrubber on a skimmer gives up the oxygenation capability, and I don’t recommend that.

Randy. I was thinking when connecting the lid to my reef octopus skimmer for recirculating. I know u said the downside is oxygen. But i noticed that my co2 scrubber by reef octopus have 2 valves at the top. I use one for my skimmer and the other one is disconnected. If i open that valve at the top? Would i be able to get oxygenation? While doing a recirculating method?

 

[Randy Holmes-Farley]

Randy. I was thinking when connecting the lid to my reef octopus skimmer for recirculating. I know u said the downside is oxygen. But i noticed that my co2 scrubber by reef octopus have 2 valves at the top. I use one for my skimmer and the other one is disconnected. If i open that valve at the top? Would i be able to get oxygenation? While doing a recirculating method?

I'm not sure what will happen if you open that valve and I'm not certain why it is there. You could try cracking it open and see if air seems to go in (good) or come put (wastes scrubbed air). It won't take much air flow to keep O2 up in most cases (IMO).

 

[Steve2020]

I'm not sure what will happen if you open that valve and I'm not certain why it is there. You could try cracking it open and see if air seems to go in (good) or come put (wastes scrubbed air). It won't take much air flow to keep O2 up in most cases (IMO).

The second valve is a bleeder valve that pulls in air and used in most cases to control the ph if it gets to high to your liking. Opening the second valve will bring in room air and combine it with the scrubber exit air going to the skimmer and lower the ph but at the same time it should also give you better oxygenation. Your choices would be: Second valve Closed = Higher ph but low if any oxygenation, valve Open = Lower ph but better oxygenation. Neither valve position gives you optimal ph and oxygenation performance at the same time IMO unless you bring in fresh air from outside the home.

 

[Randy Holmes-Farley]

Sounds good to me!

 

[Notsolostfish]

The second valve is a bleeder valve that pulls in air and used in most cases to control the ph if it gets to high to your liking. Opening the second valve will bring in room air and combine it with the scrubber exit air going to the skimmer and lower the ph but at the same time it should also give you better oxygenation. Your choices would be: Second valve Closed = Higher ph but low if any oxygenation, valve Open = Lower ph but better oxygenation. Neither valve position gives you optimal ph and oxygenation performance at the same time IMO unless you bring in fresh air from outside the home.

Right now i dont have it in recirculating way, but i already have the lid, and i was thinking of putting in recirculating way. So if i decide to do it in recirculating way. I can simply just open the second valve at the top? And i wont have o2 issues? Like randy was saying? And i would have more media life?

 

[Steve2020]

Right now i dont have it in recirculating way, but i already have the lid, and i was thinking of putting in recirculating way. So if i decide to do it in recirculating way. I can simply just open the second valve at the top? And i wont have o2 issues? Like randy was saying? And i would have more media life?

If you open the second valve you will be allowing some room air to enter the skimmer thus adding O2 to the skimmer. Just keep in mind that the ph increase you would get from the scrubber with the second valve closed will drop with the second valve open. How much of a difference will depend on how much the valve is open/closed. You could try different valve positions and monitor what your ph does. I would give it a couple of days per position. You could also adjust both valves to see what you get. Restricting flow out of one and increasing the other and so on. Remember to also monitor your skimmers reaction when adjusting both valves.
Recirc will give you more media life, but you will see the media exhaust quicker with the second valve open vice closed because you are allowing room air to enter the skimmer which has a higher CO2 level and that CO2 will be scrubbed thus exhausting the media at a faster rate than if the valve was closed.

 

[Randy Holmes-Farley]

Do we know for sure that it makes media deplete faster to open that valve, or just that the pH effect is smaller with the same or maybe even a lower depletion rate?

I'm not really seeing a full rationale for it to deplete faster if the pH effect is reduced. With less air flow through the scrubber, that might prevail over the small increase in CO2 in the air coming back to the scrubber because the pH is lower.

 

[Steve2020]

Do we know for sure that it makes media deplete faster to open that valve, or just that the pH effect is smaller with the same or maybe even a lower depletion rate?

I'm not really seeing a full rationale for it to deplete faster if the pH effect is reduced. With less air flow through the scrubber, that might prevail over the small increase in CO2 in the air coming back to the scrubber because the pH is lower.

Sorry with the late response. Had to take one of my dogs for his semi-annual checkup.
For one that has run a few scrubber arrangements including the arrangement @Notsolostfish wants to run I can tell you that my media depleted >2 times as fast as what I have been running now since the beginning of August 2022. Now you may disagree with what I am about to explain but I believe the reason it depletes faster is that you are now also pulling in air thru that second valve to the skimmer that has a higher CO2 value than if you were only doing a recirc from the scrubber. That air that now has more CO2 will go to the skimmer venturi, get mixed with water within the skimmer, that water gets discharged into the sump thus adding CO2 to the water. That air that has more CO2 in it also rises to the top of the skimmer body in form of bubbles/foam and burst. That air that has more CO2 now goes to the scrubber and gets scrubbed thus depleting CO2 media faster than if you were just doing a recirc from the scrubber.

Also how do you have less airflow to the scrubber unless you physically restrict it mechanically or electrically? The skimmer pump creates a positive pressure and that positive pressure air which normally gets exhausted thru holes in the top of the skimmer cup lid now go to the scrubber. The scrubber works on vacuum created by the skimmer venturi thus it pulls the air from the skimmer thru the media in the scrubber. The only way to get less airflow to the skimmer is to restrict the air going to the venturi. You can do this if you have an adjustable DC skimmer pump by slowing the pump down or in the case of @Notsolostfish also restricting airflow with the valves on his scrubber. If you do either of the two you will have to adjust the water level in the skimmer to get approx the same amount of skimmate. That's why I told him to watch how his skimmer reacts if he starts adjusting the valves.

Also depending on the skimmer pump speed , this will also have an effect on media depletion, more liters of air = more CO2 thru the media = faster media depletion.

This was my setup prior to what I run now and a chart showing the ph. It did not give me the results I was looking for.


A couple of days after changing my setup to what I run now from the above setup. I controlled the upper ph limit @ 8.40 with a electronic solenoid valve controlled the the GHL Profilux.

 

[Randy Holmes-Farley]

Also how do you have less airflow to the scrubber unless you physically restrict it mechanically or electrically? The skimmer pump creates a positive pressure and that positive pressure air which normally gets exhausted thru holes in the top of the skimmer cup lid now go to the scrubber. The scrubber works on vacuum created by the skimmer venturi thus it pulls the air from the skimmer thru the media in the scrubber. The only way to get less airflow to the skimmer is to restrict the air going to the venturi. You can do this if you have an adjustable DC skimmer pump by slowing the pump down or in the case of @Notsolostfish also restricting airflow with the valves on his scrubber. If you do either of the two you will have to adjust the water level in the skimmer to get approx the same amount of skimmate. That's why I told him to watch how his skimmer reacts if he starts adjusting the valves.

As others with similar setups have confused me, I'm a bit confused on the idea of pulling in air through that valve being open. Where does that extra air that goes in get out? It cannot just be pushed through the scrubber as that air flow would increase constantly until it was a wind tunnel.

So my though is that the venturi is pulling in air, and that air can either come all from the scrubber, or part from the scrubber and part from the open valve.

If part is coming from the open valve, the flow through the scrubber is less.

 

[Steve2020]

As others with similar setups have confused me, I'm a bit confused on the idea of pulling in air through that valve being open. Where does that extra air that goes in get out? It cannot just be pushed through the scrubber as that air flow would increase constantly until it was a wind tunnel.

So my though is that the venturi is pulling in air, and that air can either come all from the scrubber, or part from the scrubber and part from the open valve.

If part is coming from the open valve, the flow through the scrubber is less.

I totally agree with what your saying. I may have an idea of what actually may be happening but then again I am a retired electrical engineer not a mechanical engineer but lets give this thought a try anyways. Lets say the skimmer pump is at a speed that's pulling in 1000L of air. For simplicity reasons for now lets assume that no air exits the skimmer standpipe. That would mean all the air no matter the source has to go thru the scrubber so you would think. So even if the valve allows 500L of air to enter the venturi and the scrubber allows the other 500L of air to the venturi for a total of 1000L how can you have 1000L of air going thru the scrubber when only 500L is coming out. You are correct. That cant happen. So where is the air going? 1000L of air has to exit somewhere. If it is all going thru the scrubber then that would mean no air would be coming in from the valve. When I was running the valve type setup I was only running two exhaust lines from the skimmer cup lid to the scrubber. The other 6 lid exhaust holes were plugged. When I would change out my filter socks I was noticing a tapping sound coming from the sump. It took a few weeks of changing the socks to figure out where the sound was coming from. The skimmer lid was popping up and down. I had determined that the amount of air I was injecting was greater than what the two airlines could pass hence a lot of air was not being scrubbed even though I was going thru media like crazy.
So lets look at the standpipe. 1000L of air has to go somewhere. If the scrubber only has 500L of air going thru it and your skimmer lid is sealed, the only other place I can think of is the air has to go out through the standpipe. I am sure you have read many complaints on this site about skimmer micro bubble issues. I am wondering if restricted skimmer cup lid exhaust is the issue with some skimmers that run normal air input and not necessarily a recirc of some kind. I am thinking that if what your saying is correct then there will probably be a more than normal abundance of microbubble exiting the standpipe. Just a thought. I may be out to lunch with it.

 

[Randy Holmes-Farley]

I totally agree with what your saying. I may have an idea of what actually may be happening but then again I am a retired electrical engineer not a mechanical engineer but lets give this thought a try anyways. Lets say the skimmer pump is at a speed that's pulling in 1000L of air. For simplicity reasons for now lets assume that no air exits the skimmer standpipe. That would mean all the air no matter the source has to go thru the scrubber so you would think. So even if the valve allows 500L of air to enter the venturi and the scrubber allows the other 500L of air to the venturi for a total of 1000L how can you have 1000L of air going thru the scrubber when only 500L is coming out. You are correct. That cant happen. So where is the air going? 1000L of air has to exit somewhere. If it is all going thru the scrubber then that would mean no air would be coming in from the valve. When I was running the valve type setup I was only running two exhaust lines from the skimmer cup lid to the scrubber. The other 6 lid exhaust holes were plugged. When I would change out my filter socks I was noticing a tapping sound coming from the sump. It took a few weeks of changing the socks to figure out where the sound was coming from. The skimmer lid was popping up and down. I had determined that the amount of air I was injecting was greater than what the two airlines could pass hence a lot of air was not being scrubbed even though I was going thru media like crazy.
So lets look at the standpipe. 1000L of air has to go somewhere. If the scrubber only has 500L of air going thru it and your skimmer lid is sealed, the only other place I can think of is the air has to go out through the standpipe. I am sure you have read many complaints on this site about skimmer micro bubble issues. I am wondering if restricted skimmer cup lid exhaust is the issue with some skimmers that run normal air input and not necessarily a recirc of some kind. I am thinking that if what your saying is correct then there will probably be a more than normal abundance of microbubble exiting the standpipe. Just a thought. I may be out to lunch with it.

I agree that bubbles leaving the skimmer in the water, or the lid popping up are both places to allow the excess air to escape.

Assuming that happens, and air is actually entering the open valve, then less air is likely going through the scrubber, though I cannot know how much less. But less air through it may deplete the scrubber more slowly.

In any case, I'd defer to actual experiments that show increased (or decreased) depletion rates, since it is too complicated to hand wave which direction the depletion rate would go. It may depend strongly on how much air goes in via the open valve relative to going by way of the scrubber.

 

[Notsolostfish]

I totally agree with what your saying. I may have an idea of what actually may be happening but then again I am a retired electrical engineer not a mechanical engineer but lets give this thought a try anyways. Lets say the skimmer pump is at a speed that's pulling in 1000L of air. For simplicity reasons for now lets assume that no air exits the skimmer standpipe. That would mean all the air no matter the source has to go thru the scrubber so you would think. So even if the valve allows 500L of air to enter the venturi and the scrubber allows the other 500L of air to the venturi for a total of 1000L how can you have 1000L of air going thru the scrubber when only 500L is coming out. You are correct. That cant happen. So where is the air going? 1000L of air has to exit somewhere. If it is all going thru the scrubber then that would mean no air would be coming in from the valve. When I was running the valve type setup I was only running two exhaust lines from the skimmer cup lid to the scrubber. The other 6 lid exhaust holes were plugged. When I would change out my filter socks I was noticing a tapping sound coming from the sump. It took a few weeks of changing the socks to figure out where the sound was coming from. The skimmer lid was popping up and down. I had determined that the amount of air I was injecting was greater than what the two airlines could pass hence a lot of air was not being scrubbed even though I was going thru media like crazy.
So lets look at the standpipe. 1000L of air has to go somewhere. If the scrubber only has 500L of air going thru it and your skimmer lid is sealed, the only other place I can think of is the air has to go out through the standpipe. I am sure you have read many complaints on this site about skimmer micro bubble issues. I am wondering if restricted skimmer cup lid exhaust is the issue with some skimmers that run normal air input and not necessarily a recirc of some kind. I am thinking that if what your saying is correct then there will probably be a more than normal abundance of microbubble exiting the standpipe. Just a thought. I may be out to lunch with it.

My ph is a bit lower than usual today. Im at 8.22 from 8.28 is that means my media is getting depleted. The color changing is only at the bottom part. Maybe because i spent a lot of time in tje basement today, doing water testing i dont know.