CO2 Scrubber Testing

[Mystical_Knight]

Awesome! Do you know how much your consumption of Alk and Ca has gone up by since adding the CO2 scrubber?

Honestly, nothing significant. But I still just have a few sps frags. Only thing really consuming anything in my tank is coralline lol

 

[smartwater101]

So my question is, are two ball valves necessary or can one be configured to both draw from the scrubber given a ph window and then move to position two and draw from outside air?

One valve isn't going to let you go back and forth.

But what you could do, is put the valve after a Y. So you'd pull from both reg and scrub at the same time. And then closing the valve would close off which ever line you installed it on.

EDIT: Personally, I'd would put it on the Reg intake. And keep it closed the vast majority of the time. If pulling from the scrub puts the pH too high, simply open the valve so more regular air is mixed in.

 

[JDowns]

I’m not sure why there is a concern over solenoids, as this is probably a lack of understanding how they function. These multi-position solenoids are used in many industries daily. If there was a concern over the length of time a coil can remain energized, then this would be part of the product specifications.

As a coil is energized there is an “in rush” of current. First your power supply must be able to handle the max wattage as this will be your in rush. The in rush is what generates the heat that can lead to coil failure. Manufacturers will also list “maximum cycles”. Many times this is listed as “x per second”. If you over cycle a coil, then the housing will not have enough time to dissipate the heat generated by the coil. Many solenoids are rated at over 100,000 cycles.

For this application I wouldn’t hesitate to use a 2 way 3 position solenoid. The duty cycle will never reach a point that the heat generated from cycling the coil should prematurely damage the coil.

The EB832 24vdc should be able to deliver the less than 5watts of in rush current needed from various manufacturers for this size valve.

 

[Rostato]

I just run mine 24/7. Ph swings from 8.35-8.5...higher ph...higher growth rate.

 

[mrjoev]

Thanks OP and everyone for this Post i have learned a lot and am excited to implement on my system.

 

[KenO]

Hooked up my CO2 scrubber to my skimmer cup today. I had been pulling in outside air and running the outside air into a jug with water. The outside air would bubble up through the water. The line running to the dual media reactors was above the water line. Thought I would try the skimmer connection. I did a temp connection before I started drilling holes and putting fittings in the lid. I had an empty media container so I used that to catch any excess moisture or skim mate from the skimmer. If it works then I will drill the lid and put in a proper fitting.

 

[Rakie]

I have honestly considered getting a co2 scrubber but at the same time, my pH is already much higher than average. my typical daytime pH is like 8.5 to 8.6+, and a night time low of 8.1-8.2

I have a hardcore smoker in the house, so my window is literally open 25/8, so that definitely helps the pH quite a bit.

 

[KenO]

I have honestly considered getting a co2 scrubber but at the same time, my pH is already much higher than average. my typical daytime pH is like 8.5 to 8.6+, and a night time low of 8.1-8.2

I have a hardcore smoker in the house, so my window is literally open 25/8, so that definitely helps the pH quite a bit.

At those levels, I wouldn't waste my money on a CO2 scrubber.

 

[Rakie]

At those levels, I wouldn't waste my money on a CO2 scrubber.

thats what i always hear. if anything I'll work kalk back in.

 

[Rostato]

I wouldn’t bother. Your ph is already near the abs ax anyone would recommend

 

[KenO]

General question: when you pull air from the skimmer cup, should you leave the other holes in the cup as holes or do they need to be plugged? If they are plugged, I would assume then all the air going to the CO2 scrubber would come direct from the skimmer cup. If the holes are left open, you will also be pulling room air through the open holes.

 

[Rostato]

Leave them open. Otherwise you’ll suck all water instead of air because of the vacuum

 

[KenO]

Leave them open. Otherwise you’ll suck all water instead of air because of the vacuum

Thanks!

 

[hart24601]

There is so much great information here, thank you for doing this all. It will help a lot of people!

 

[KenO]

So I did some experimenting and here is what I found out. First of all I know that I use to have a high around 800ppm CO2 level in my house. I had an whole house air exchange unit installed. My CO2 levels are now around 500 or less. I measured outside air in my area and it measures between 400-405ppm. So the air exchanger is doing a good job. Doing this helped my pH level of my aquariums but I was still running low pH level of 7.8-7.87. Prior I was running more in the 7.7 range.

1st Test: Pull in outside air to the skimmer.
Result: This was an easy one since when I built my house I had a 1/2" PVC pipe installed for this purpose. pH levels came up a little to around 7.9-7.95. I had eliminated a good portion of the CO2 in my house so a slight rise is all I was going to get.

2nd Test: Pull in outside air and let the outside air bubble up through a jug of water to add humidity and run the more humid outside air through a CO2 scrubber.
Result: pH levels only came up a little more to around 8.0.

3rd Test: Pull air from the skimmer cup into the CO2 scrubber.
This gave me the highest rise of pH. I was now running a high pH of 8.16 and a low of 8.09. Not bad.

4th Test: I have an ATS so I thought I would see if pulling the humid air from it would give me more moisture vs pulling from the skimmer.
I had pretty much the same increase as with pulling air from the skimmer cup, so no real change.

5th Test: Pull air from the ATS and let it bubble up through a media canister to add more humidity to the air.
Results: I live in AZ. Right now our outside humidity levels are in the single digits during the day and rise to between 20-30% at night. My house humidity level even with all the aquariums, I have 700+ gallons amongst several tanks my indoor levels are around 35%. I evaporate 4+ gallons of water a day. Yes I have 3 separate ATO systems, but I could use a couple more. Well this test definitely added more moisture I could see condensation in the tubing, but my pH levels went down slightly and I couldn't get back to the 8.16 high I had hit. I looked and there isn't any moisture or water in the bottom of the first CO2 reactor. The media has very little purple and I have 2 - 1.5L media canisters full of soda lime (Sodasorb). So there is plenty of media available.

So I'm back to just pulling from the skimmer. pH numbers are pretty much back to the high around 8.16 and a low of 8.07.

I'm not sure that if you have too much moisture and if that has a negative effect with the CO2 media? The bags I have say high humidity and the data I found online said 77% humidity.

 

[JDowns]

I'm not sure that if you have too much moisture and if that has a negative effect with the CO2 media? The bags I have say high humidity and the data I found online said 77% humidity.

A test I've wanted to do is to add a humidity sensor in the mix. I have seen that if there is too much condensation in the lines that will negatively affect pH. When this happens I've noticed that the media will clump together. Drilling a hole in the line to allow fresh drier air does help. I think that the media can become saturated with moisture lessening the ability to scrub CO2.

 

[mitch91175]

A test I've wanted to do is to add a humidity sensor in the mix. I have seen that if there is too much condensation in the lines that will negatively affect pH. When this happens I've noticed that the media will clump together. Drilling a hole in the line to allow fresh drier air does help. I think that the media can become saturated with moisture lessening the ability to scrub CO2.

Hey @JDowns, you ever decide if you are going to share the design to build the CO2 monitors that you used for the scrubber testing?

 

[KenO]

A test I've wanted to do is to add a humidity sensor in the mix. I have seen that if there is too much condensation in the lines that will negatively affect pH. When this happens I've noticed that the media will clump together. Drilling a hole in the line to allow fresh drier air does help. I think that the media can become saturated with moisture lessening the ability to scrub CO2.

I will need to see if the media is clumped or not. I have since reduced the amount of moisture and I'm not seeing it building up in the tubing. Hard to tell how things are working right now. I had to turn my whole house air exchanger off. Too many fires right now in AZ. I don't want to bring in smoky air.

 

[bigcheese]

@JDowns ...
Found this thread as I picked back up my coursework for rebreather diving certification, and had a few thoughts.
There are a few axioms that apply to co2 scrubbers in rebreathers that you might be able to use here.

1. Temp for longest life. Keeping the absorbent warmer is a sure-fire way to increase efficiency and longevity. I'm thinking about mounting mine in the sump itself to add a few degrees and stabilize the temp.

2. Temp for monitoring depletion. While scrubbing, heat is generated. At about 90-95% depletion, there is a significant drop in heat produced, and therefore absorbent media temp. Rebreather manufacturers use this, so we should be able to as well.

3. Media shape / grade. The finer the media, the longer it lasts. I've heard (but cannot confirm) Intersorb 812 gives greater longevity than Sofnolime 797 or most medical-grade soda lime. No idea what the grade/mesh size of the BRS media is, so I can't compare.

4. Humidity control.
Rebreathers have water traps, but I don't think they'd work for continuous duty. Shooting for about 60-70% RH on the inlet would probably be my best guess for efficiency. I'm also thinking keeping the reactor body warmer may alleviate some of the condensation issues caused by skimmer air recirc.

One other thought I had was to create a "drip loop" in the airline between the skimmer and scrubber, with a "t" at the apex. Adding a piece of airline to the perpendicular and dropping the other end into the sump (or a container of water) should drop condensation out of the line before it gets to the scrubber, without loss of suction.
Just my 2 cents, I'll stop procrastinating now and get back to the books.

 

[JDowns]

@JDowns ...
Found this thread as I picked back up my coursework for rebreather diving certification, and had a few thoughts.
There are a few axioms that apply to co2 scrubbers in rebreathers that you might be able to use here.

1. Temp for longest life. Keeping the absorbent warmer is a sure-fire way to increase efficiency and longevity. I'm thinking about mounting mine in the sump itself to add a few degrees and stabilize the temp.

2. Temp for monitoring depletion. While scrubbing, heat is generated. At about 90-95% depletion, there is a significant drop in heat produced, and therefore absorbent media temp. Rebreather manufacturers use this, so we should be able to as well.

3. Media shape / grade. The finer the media, the longer it lasts. I've heard (but cannot confirm) Intersorb 812 gives greater longevity than Sofnolime 797 or most medical-grade soda lime. No idea what the grade/mesh size of the BRS media is, so I can't compare.

4. Humidity control.
Rebreathers have water traps, but I don't think they'd work for continuous duty. Shooting for about 60-70% RH on the inlet would probably be my best guess for efficiency. I'm also thinking keeping the reactor body warmer may alleviate some of the condensation issues caused by skimmer air recirc.

One other thought I had was to create a "drip loop" in the airline between the skimmer and scrubber, with a "t" at the apex. Adding a piece of airline to the perpendicular and dropping the other end into the sump (or a container of water) should drop condensation out of the line before it gets to the scrubber, without loss of suction.
Just my 2 cents, I'll stop procrastinating now and get back to the books.

Really good points @bigcheese .

While recirculating does reduce the amount of CO2 to be scrubbed, it wasn't as much as I suspected. I think your (4) point really is the key. If the media is too humid then CO2 reduction is inhibited, and too little then the media is far less effective. I think your spot on that shooting for around 70% is a good target. I found that just drilling a small hole in the line to allow fresh air in is keeping a good balance for humidity and stops either the line or the canister from accumulating to much moisture.

The recent @BRS tv episode had a great idea of just using a simple valve as a tee to regulate fresh air input.