CO2 Scrubber Testing

[JDowns]

This is a carry-over from this thread..

https://www.reef2reef.com/threads/an-easy-way-to-increase-your-tanks-ph-with-a-co2-scrubber.57609/page-12

These tests are geared towards specifically measuring CO2 inlet and outlet values and the efficiency of differing methods in scrubbing CO2 via a reactor.

I’ll be using two Amphenol Telaire T6713 CO2 sensors. One to measure CO2 on the inlet side of the reactor and another on the outlet side of the reactor. This way the amount of CO2 reduction can be directly measured independently to PH. I plan on running four test scenarios over a period of 7 days. The following test procedures will be adhered to.

1. Water change of 25 gallons on a Red Sea Reefer 525 XL (my normal weekly routine) with Brightwell Neo Marine with a target KH of (9.0) (my weekly target KH is 8.6 +/- 0.3), CA (450), MG (1440).

2. Sensors will be calibrated prior to each week with reference 400ppm CO2 gas, and offsets inputted into memory.

3. CO2 values will be polled every (3) seconds and displayed on the local touchscreen, but data logged ever (5) minutes resulting in (20) logged values ever (5) minutes. An average of the (20) values will be data logged at the end of each (5) minutes.

4. Alkalinity, Calcium, and Magnesium will be tested once in the AM and once in the PM daily. I had initially planned on not bothering with these measurements, but since after initially installation I saw an odd decrease in KH over two days, so I think adding these values may have some merit.

5. PH will be logged via Apex and imported into the data sets. I installed a new PH probe and calibrated on 10/19.

6. CO2 absorption media will be replaced prior to each test.

The following are the four tests that I want to complete.

1) Standard media with no humidification.

a) This is the typical installation and methodology.

2) Standard media with RO water in the bottom of the canister.

a) The BRS Reactors allow for a small amount of water to be placed at the bottom of the canisters to allow for humid air to flow through the media presumably to aid in CO2 absorption.

3) Standard media with Inlet Line pulling recirculated humidified air from the skimmer cup.

a) I will not be able to perform this test at 100% humidification due to two factors. One the sensors do not perform well with humidity levels greater than 80% and condensation on electrical components is generally a no – no. Care should also be taken to avoid condensation buildup in lines that can create a blockage in airflow, condensation can also build up in the reactor canister that will either require manual or automatic drainage.

4) Standard media with Inlet Line pulling air from reference 400ppm (ambient outdoor CO2 levels) gas.

a) This should replicate an airline drawing air from outdoor fresh air.

I installed the new jumbo scrubber and media from @BRS Saturday morning and started a dry run test before I start each weekly testing. This will establish a decent baseline and ensure the equipment is operating as expected. I’m pretty sure I already know the best method for increasing PH while also increasing the lifespan of the absorption media but performing the tests should give an accurate reasoning and expectations for each type of installation method.


Test #1 will start November 3rd.


Stay tuned for results….

The reactor is clearly working, as I've already seen a dramatic increase in PH over two days.

 

[HotRocks]

Interesting Study, thanks for the contribution. Looking forward to your results.

 

[ca1ore]

I think there is little question that CO2 scrubbers work. It is less clear that they impact pH in a consistently material way - some folks report significant increases, others not (I’m in that camp). Even if it does help to boost pH, does that translate to a healthier tank? I’ve seen no correlation of pH to tank ‘health’. Your test is cool, I’m just unconvinced that the effort to run and maintain a scrubber is worthwhile.

 

[JDowns]

I think there is little question that CO2 scrubbers work. It is less clear that they impact pH in a consistently material way - some folks report significant increases, others not (I’m in that camp). Even if it does help to boost pH, does that translate to a healthier tank? I’ve seen no correlation of pH to tank ‘health’. Your test is cool, I’m just unconvinced that the effort to run and maintain a scrubber is worthwhile.

The point of the tests really has nothing to do with PH or tank health, as there are many variables outside of CO2 scrubbing that can effect those variables.

The test(s) are designed, simply to isolate the differing methods of installation, and measure which results in a greater reduction in CO2 on the outlet, resulting in a more efficient CO2 scrubbing methodology. It may also answer some questions such as: Is it worth while to run a pipe/tubing for outside air? Is it worth while to maintain water for evaporation in the bottom of the canister? Is it worth while to drill a hole for tubing to recirculate air from the skimmer?

Other tests can determine why some have success and others have failures in increasing PH. Simple things like less gas exchange from surface turbulence/overflow, or you may simply live in a household/business that any amount of CO2 scrubbing simply wouldn't be efficient.

 

[ca1ore]

Understood, which is why I called your test cool. We need more of these kind of data-driven experiments to combat anecdotal opinion. But one should not lose sight of the ultimate goal. I’ll be interested to see what you find.

 

[Rostato]

This is awesome. Can’t wait to see results. Thanks for taking the time to do this.

 

[dantimdad]

Following

 

[mitch91175]

Following along. Running a scrubber myself.

 

[Rostato]

Yeah I just started running one myself as well. I have the air intake hooked up to the lid of my skimmer to keep the air humid and recirculating

 

[ShadowR55]

Definitely following along, I installed two large c02 reactors pulling outside air and my PH ranges from 8.10 at night and 8.25 during the day. I can’t break 8.25. I definitely see faster growth with a higher PH. My outlet side ambient C02 is 450ppm, indoor ranges from 550-750ppm and during my sons birthday party, it was 1300ppm.

I just put the CO2 sensor on top of the skimmer cup to see if the C02 level is lower but it’s not a good measure because in theory if you can scrub the same air over and over then it should get down to 0 and use very minimal C02 media unless of course the humidity adversely affects the media and uses it up, or maybe the color changing compound will change colors even though the media really isn’t used up. These are just my thoughts, I’m not a scientist by any means. Just food for thought.

Thank you for your contribution to the hobby.

 

[ShadowR55]

Think I found my answer, CO2 levels are measuring 300 with the desktop C02 sensor sitting on the lid of my skimmer next to the skimmer holes. Outside air is 450 here, so I will be rerouting my intake to the top of the skimmer and we’ll see how that affects my PH.

Also, an upside is that I can now remove the carbon filter pad sitting on top of the skimmer holes to stop the smell.

 

[JDowns]

Testing will start this Saturday. Sorry for the week delay, but having my tonsils removed set me back a little longer than expected.

On the plus side it allowed me time for a few weeks of testing and data-logging since I switched to Kalk and 2-Part dosing over a month ago and finally got things dialed in, and want a decent baseline for Alkalinity/Calcium/Magnesium usage.

I won't say what setup I'm currently running, but I have seen my weekly average of 7.98 (low 7.82 / high 8.18) go to average 8.24 (low 8.16 / high 8.46).

I will be adding one more test scenario, or you can think about it as splitting one of the tests into two. My concern with running the intake from the skimmer with no venting is due to the excess condensation buildup. I wonder if this condensation can form a layer on the media not allowing enough air to pass through causing a non-permeable membrane on the media.

The following data will serve as my baseline prior to starting the CO2 portion of the tests. Alkalinity was adjusted daily anytime the test resulted in a value less than or equal to 8.3, along with equal dosing of Calcium to match.

I'm currently having to daily dose 2800(ml) of saturated Kalk along with 30(ml) of Alkalinity and Calcium to maintain target levels.

 

[Rostato]

I’m surprised you feel the need to run Kalk while also running the co2 scrubber. But the excess condensation is defy something to think about. Here my reactor after 9 days of running out of the skimmer.

My current PH range since implementing this is 8.3-8.39 daily.

It was 7.9-8.1 prior. My alkalinity consumption went up about 20%

 

[ShadowR55]

I’m surprised you feel the need to run Kalk while also running the co2 scrubber. But the excess condensation is defy something to think about. Here my reactor after 9 days of running out of the skimmer.

My current PH range since implementing this is 8.3-8.39 daily.

It was 7.9-8.1 prior. My alkalinity consumption went up about 20%

Are those pre-skimmer output numbers and post numbers?

I definitely have condensation in mine already after less than 1 day.

 

[JDowns]

I’m surprised you feel the need to run Kalk while also running the co2 scrubber.

The switch to Kalk plus Two Part from just Two Part was less about PH/CO2 then it was based on a recommendation from a friend to try Kalk out, and see if I could fix a few issues with some corals. Plus I evaporate just over a gallon each day so it made sense to incorporate 75% of my evaporation rate into Kalk dosing anyways, the other 25% +/- comes from a RO/DI container on a float switch. This way I don't have to compensate for differing evaporation rates.

 

[Fr4nkthet4nk]

following

 

[Larry L]

But the excess condensation is defy something to think about.

It's pretty easy to trap the most of the excess condensation before it reaches the media. I used an old Kent Marine jar and made it so the two pieces of tubing only reach a little way into the top of it, the water collects in the bottom:

 

[Rostato]

Are those pre-skimmer output numbers and post numbers?

I definitely have condensation in mine already after less than 1 day.

I never ran the co2 scrubber without the air inlet being from my skimmer because I need my media to last longer.

It's pretty easy to trap the most of the excess condensation before it reaches the media. I used an old Kent Marine jar and made it so the two pieces of tubing only reach a little way into the top of it, the water collects in the bottom:

That seems like it may make it less effective to me. But maybe I’m wrong. How long does your media last?

I unfortunately don’t have the room to add something like that. I technically don’t even have the room for the scrubber, but I’m making it work.

 

[Larry L]

That seems like it may make it less effective to me. But maybe I’m wrong. How long does your media last?

No less effective, the air going into the scrubber is still very humid, just the big drops of water get collected before they get into the reactor. My media lasts several weeks, not exactly sure because I don't normally wait until it all goes purple, I change out the bottom half when it turns purple so that I know it's never totally depleted.

 

[ShadowR55]

So, I’m going to disconnect my CO2 scrubber from my skimmer and connect it back to outside air. Looks like I’m using up media quicker and my PH has been dropping since I connected it on Wednesday.

Here is a picture of how much media changed color in 7 days from my first jumbo reactor using outside air:

Here it is after 3 days of having it connected to my skimmer cup:

Here is a screenshot of my PH:

You can see that after I connected it to my skimmer, the PH has been dropping and I used up more media. Maybe the humidity is causing it not to be as efficient.