Tuning a Skimmer / CO2 Scrubber for pH Control

[arking_mark]

Do you have a photo of your Co2 Scrubber set-up along with the skimmer and solenoid? I am looking to set one up myself and trying to see what a good set-up looks like....hard to find on YouTube. I have the Ice Cap Co2 scrubber

Sure...

Aeraqua Duo top has 4 holes that fit 1/4" ro tubing. I use 2 of them with elbows on the inside and then connect to a 3/8 ro tubing which is the perfect size for all the rest of the connections including the air intake.

This goes out the back of the tank. I keep the recirculation tube elevated so as to have no spots where the damp air can fill with water.

This leads down to the dual chamber scrubber.

Which has the solenoid valve sitting on top and controlled by the GHL switched outlets.

 

[jphilip813]

Sure...

Aeraqua Duo top has 4 holes that fit 1/4" ro tubing. I use 2 of them with elbows on the inside and then connect to a 3/8 ro tubing which is the perfect size for all the rest of the connections including the air intake.

This goes out the back of the tank. I keep the recirculation tube elevated so as to have no spots where the damp air can fill with water.

This leads down to the dual chamber scrubber.

Which has the solenoid valve sitting on top and controlled by the GHL switched outlets.

Man, that is a massive and awesome set-up. I have two questions, one is the solenoid tubing connected to anything else other than running directly to the "T" which is I assume is connected to the other end/input of the Co2 scrubber? The other question is what is that liquid in the Icecap branded cylinder?

 

[arking_mark]

Man, that is a massive and awesome set-up. I have two questions, one is the solenoid tubing connected to anything else other than running directly to the "T" which is I assume is connected to the other end/input of the Co2 scrubber? The other question is what is that liquid in the Icecap branded cylinder?

Solenoid is just connected to the tee as air will follow least resistance. So when it opens, it's mostly pulling un-scubbed air.

That is an Icecap Kalkwasser reactor.

 

[jphilip813]

Solenoid is just connected to the tee as air will follow least resistance. So when it opens, it's mostly pulling un-scubbed air.

That is an Icecap Kalkwasser reactor.

Thanks for the info. I just ordered my Neptune Solenoid, should be arriving sometime later this week... the first time I had to deal with lowering pH...(also I just moved to West Texas from Maryland)...

 

[arking_mark]

Thanks for the info. I just ordered my Neptune Solenoid, should be arriving sometime later this week... the first time I had to deal with lowering pH...(also I just moved to West Texas from Maryland)...

Fear the turtle!

 

[Plandauesq]

#2/3. I do not think there is a rationale for wanting ANY recirculation of the water. Yes, recirculation of water raises the pH most/ removes CO2 most for a single pass through the skimmer, but a skimmer on a reef tank is not single pass device.

If the goal is to drive out CO2, it is always best to have lower pH/higher CO2 water in the skimmer to maximize the removal of CO2 (by maximizing the difference between the water and the air CO2 level). Hence, no water recirculation will export the most CO2 over time.

Just trying to understand this. I have a Reef Octopus skimmer with the Varios Pump. If I increase the speed of the pump to the max, will that help increase pH?

 

[arking_mark]

Just trying to understand this. I have a Reef Octopus skimmer with the Varios Pump. If I increase the speed of the pump to the max, will that help increase pH?

It will drive your pH to equilibrium with air intake CO2. So if your indoor air is high in CO2 (a common scenario) then it will drive your pH to lower #s like 7.8. If you are using CO2 scrubbed or outdoor air it will drive you to higher pH like 8.2 or higher.

 

[arking_mark]

Something I didn't account for, beautiful fall weather with windows wide open. With no higher CO2 indoor air the skimmer still runs with the solenoid to try and bring down the pH. It doesn't work, notice the plt highs.

 

[jphilip813]

Thanks for the info. I just ordered my Neptune Solenoid, should be arriving sometime later this week... the first time I had to deal with lowering pH...(also I just moved to West Texas from Maryland)...

Update, I returned the Neptune Solenoid...it got TOO HOT, and went for a mechanical one that opened at the set PH setting (>8.37) I got it off amazon....Works GREAT...using a recirculating set-up along with Kalk mixer that only comes on if the PH is lower than 8.25 for about 4hrs of the day

 

[paradizecityz]

It will drive your pH to equilibrium with air intake CO2. So if your indoor air is high in CO2 (a common scenario) then it will drive your pH to lower #s like 7.8. If you are using CO2 scrubbed or outdoor air it will drive you to higher pH like 8.2 or higher.

Maybe this is my issue all along? I have my skimmer running at max 100% and was only seeing like 7.7 ph...I've added a co2 scrubber and now seeing 7.8, maybe 7.9 on a good day...should I lower the skimmer speed to like 50% then?

 

[arking_mark]

Maybe this is my issue all along? I have my skimmer running at max 100% and was only seeing like 7.7 ph...I've added a co2 scrubber and now seeing 7.8, maybe 7.9 on a good day...should I lower the skimmer speed to like 50% then?

Well aerated water without a Calcium Carbonate Reactor really can't be below 7.8. So question your below 7.8 pH measurements.

If your skimmer is pulling in CO2 scrubbed air...then more is better.

Think of it this way. All the water movement in your tank (especially the surface) is acting to equalize the CO2. In home air is typically high in CO2 which directly effects (lowers) your pH.

Your skimmer with CO2 scrubber is trying to equalize your tank CO2 with air that is low in CO2 which will raise pH.

So both mechanisms are usually in competition.

My original skimmer was sized appropriately for my tank and was able to provide some pH boost with a scrubber. It wasn't till I put in an oversized skimmer that I was really able to drive and control my pH.

 

[paradizecityz]

Well aerated water without a Calcium Carbonate Reactor really can't be below 7.8. So question your below 7.8 pH measurements.

If your skimmer is pulling in CO2 scrubbed air...then more is better.

Think of it this way. All the water movement in your tank (especially the surface) is acting to equalize the CO2. In home air is typically high in CO2 which directly effects (lowers) your pH.

Your skimmer with CO2 scrubber is trying to equalize your tank CO2 with air that is low in CO2 which will raise pH.

So both mechanisms are usually in competition.

My original skimmer was sized appropriately for my tank and was able to provide some pH boost with a scrubber. It wasn't till I put in an oversized skimmer that I was really able to drive and control my pH.

I use my Apex to measure pH and recently have recalibrated the pH probe using their solution so I'm not sure. I have a Simplicity 240 DC skimmer and using CO2 scrubber setup in recirculation right now. I got all this mainly to help with pH boost but am just going to leave it alone.

I feel like I have good water movement with my 2 Icecap Gyres 4K and I have a small wavemaker in the return section of my sump as well.

It did give a boost but I thought there would be more. Sounds like I need bigger skimmer to pull in more air but I'm not going to spend more money on this lol

 

[arking_mark]

I use my Apex to measure pH and recently have recalibrated the pH probe using their solution so I'm not sure. I have a Simplicity 240 DC skimmer and using CO2 scrubber setup in recirculation right now. I got all this mainly to help with pH boost but am just going to leave it alone.

I feel like I have good water movement with my 2 Icecap Gyres 4K and I have a small wavemaker in the return section of my sump as well.

It did give a boost but I thought there would be more. Sounds like I need bigger skimmer to pull in more air but I'm not going to spend more money on this lol

Completely understand.

I chased pH, got great stability, but can't really say if it's beneficial. But I enjoyed the journey and learning.

I feel my tank is coming along well. I'm approaching 1 year with never having an ugly stage...but I contribute that to automating most of my maintenance.

In terms of value, here is how I see it...besides the basics:

1. Roller Mat
2. ATO
3. AWC
4. Alk controlled automation
5. Salinity controlled automation
6. Auto feeder
7. Automated dosing
8. pH Control

 

[fryman]

I use my Apex to measure pH and recently have recalibrated the pH probe using their solution so I'm not sure. I have a Simplicity 240 DC skimmer and using CO2 scrubber setup in recirculation right now. I got all this mainly to help with pH boost but am just going to leave it alone.

I feel like I have good water movement with my 2 Icecap Gyres 4K and I have a small wavemaker in the return section of my sump as well.

It did give a boost but I thought there would be more. Sounds like I need bigger skimmer to pull in more air but I'm not going to spend more money on this lol

How big is your tank? I use the same skimmer (simplicity 240) on a 120 gallon display and I set it up in recirculating mode to turn on when pH drops below 8.25. So long as I maintain the media my pH doesn't drop much below that. I have it turn off at 8.3, and pH is maintained between 8.2 and 8.4 this way.

Biggest problem is my media doesn't last as long as I'd like. Before recirculating it lasted less than a week, in recirc mode it lasts maybe 2 weeks. I use a BRS reactor so that's alot of media and it gets expensive. It's easy to tell when I run out of media tho, pH drops to 8.1 at night

 

[paradizecityz]

How big is your tank? I use the same skimmer (simplicity 240) on a 120 gallon display and I set it up in recirculating mode to turn on when pH drops below 8.25. So long as I maintain the media my pH doesn't drop much below that. I have it turn off at 8.3, and pH is maintained between 8.2 and 8.4 this way.

Biggest problem is my media doesn't last as long as I'd like. Before recirculating it lasted less than a week, in recirc mode it lasts maybe 2 weeks. I use a BRS reactor so that's alot of media and it gets expensive. It's easy to tell when I run out of media tho, pH drops to 8.1 at night

I have a 120 gallon DT and about another 20 gallons in the sump. I would take that 8.1 LOL

 

[fryman]

Something I didn't account for, beautiful fall weather with windows wide open. With no higher CO2 indoor air the skimmer still runs with the solenoid to try and bring down the pH. It doesn't work, notice the plt highs.

8.35 is pretty good. I wouldn't start to get worried unless you go over 8.5

I have a 120 gallon DT and about another 20 gallons in the sump. I would take that 8.1 LOL

Grow more coral, lol. I know it's easier said than done.

Macroalgae in the sump on reverse photo-period helps. Coral and algae can have a big impact on pH ime. I believe the coral zooxanthellae sucks up CO2 during the day and then macroalgae does the same at night. Best to have something photosythesizing 24 hours a day.

 

[paradizecityz]

8.35 is pretty good. I wouldn't start to get worried unless you go over 8.5

Grow more coral, lol. I know it's easier said than done.

Macroalgae in the sump on reverse photo-period helps. Coral and algae can have a big impact on pH ime. I believe the coral zooxanthellae sucks up CO2 during the day and then macroalgae at night. Best to have something photosythesizing 24 hours a day.

I have chaeto growing in my refugium on opposite light schedule. My sump is small so I had to do a small external refugium instead.

Didn't think about corals sucking up CO2, might have to add more than

 

[Chrisv.]

@arking_mark so is your conclusion that with an oversized skimmer one can use a recirculating scrubber without a solenoid and just turn the skimmer off and on to control ph?


is you kalk reactor dosing when the ph hits a certain low point or always dripping? If on a controller, what are your control parameters?

I love this thread.

 

[arking_mark]

@arking_mark so is your conclusion that with an oversized skimmer one can use a recirculating scrubber without a solenoid and just turn the skimmer off and on to control ph?


is you kalk reactor dosing when the ph hits a certain low point or always dripping? If on a controller, what are your control parameters?

I love this thread.

It's a competition between MY CO2 sources and sinks. For my particular setup:
[Source] Higher CO2 house air (typically between 600-800) --> main source of CO2 and would drive my pH to ~7.9
[Source] Lighter live stock for tank size --> minor impact on CO2 and pH
[Source] Oversized Skimmer with house air (solenoid) --> able to rapidly drive CO2 into my tank
[Sink] Kalkwasser drip to evaporation limit --> +0.1ph impact in my opinion
[Sink] Oversized Skimmer with recirculating CO2 Scrubber --> able to rapidly drive CO2 out of my tank
[Sink] Tank photosynthesis --> can have a nice impact during lighting schedule up to about 0.05
[Sink] Reverse lighting refugium --> so far a minor impact for pH at night, maybe 0.02

I do not adjust or control Kalkwasser as it really used to provide balanced Ca/Alk. The pH is just a side benefit.

Control parameters: Setpoint = 8.26 w/ a 0.05 hysteresis.
- Recirculating CO2 Scrubbed Skimmer on when tank drops to 8.23
- Skimmer with house air then tank reaches 8.28
- Otherwise skimmer is off

Tank normally stays between 8.23 and 8.28.

 

[Chrisv.]

It's a competition between MY CO2 sources and sinks. For my particular setup:
[Source] Higher CO2 house air (typically between 600-800) --> main source of CO2 and would drive my pH to ~7.9
[Source] Lighter live stock for tank size --> minor impact on CO2 and pH
[Source] Oversized Skimmer with house air (solenoid) --> able to rapidly drive CO2 into my tank
[Sink] Kalkwasser drip to evaporation limit --> +0.1ph impact in my opinion
[Sink] Oversized Skimmer with recirculating CO2 Scrubber --> able to rapidly drive CO2 out of my tank
[Sink] Tank photosynthesis --> can have a nice impact during lighting schedule up to about 0.05
[Sink] Reverse lighting refugium --> so far a minor impact for pH at night, maybe 0.02

I do not adjust or control Kalkwasser as it really used to provide balanced Ca/Alk. The pH is just a side benefit.

Control parameters: Setpoint = 8.26 w/ a 0.05 hysteresis.
- Recirculating CO2 Scrubbed Skimmer on when tank drops to 8.23
- Skimmer with house air then tank reaches 8.28
- Otherwise skimmer is off

Tank normally stays between 8.23 and 8.28.

Does all of your top off come through the kalk reactor?

Interesting that you you attribute 0.1 increase in pH to kalk. I guess I would have expected more. This is really valuable information.

It seems like oversizing the skimmer really has helped with CO2 exchange.

Would you mind pulling data from your controller logs to get a % time skimmer on with CO2, % time skimmer on with room air, % time skimmer off?

I know you mentioned earlier in the thread that you're less interested in the skimmer for filtration and more interested in it for pH control. I think this is the right idea. I have run many tanks (even large tanks!) with no skimmer. That being said, do you still get some skimmate production with this setup?

Thanks for taking the time to post this thread. It's incredibly useful. I feel like many CO2 scrubber threads are from people who have seen only marginal increases in pH and have not been successful in setting up in a way that manages both pH and moderates scrubber media consumption.