CO2 Scrubber Testing

[BestMomEver]

That’s awesome info. Check your alk consumption as well. Wonder if after a certain threshold of ph it starts consuming more

It does.... and magnesium too.

 

[BestMomEver]

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.

I did kalk in my ATO for a while. Then I checked parameters. Calcium was off the charts, dkh was 12+. I tried to adjust the kalk ratio and it was so hard because the tank evaporated differing amounts every day. I finally got a doser, part A, B, and mag from BRS and later, a CO2 scrubber.

 

[CNDReef]

Over the years I found that kalk is only done correctly by dosing slightly less than your evaporation rate. The ATO thing is flawed like you experienced.

 

[JDowns]

I followed the advice of a friend before I went the Kalk route.

I was already running two-part, and an ATO directly from my 75 gallon RO reservoir. I spent a few weeks measuring my daily top of rate, then took 75% of that as my max Kalk dosage. Fortunately that Kalk dosage at full saturation was less than my two part dosing to maintain Alk/Cal. I then spent a few weeks measuring Alk/Cal twice a day to determine how much two part to adjust for. This way your Kalk dosage never exceeds your ATO needs and your Alk/Cal needs. It does come at an additional expense of an extra doser, but is a safer approach overall.

My current daily dosing is 2800ml saturated Kalk, and 50ml each of Alk/Calcium.

 

[JDowns]

I'm going to have to look into a few things this weekend since some initial numbers aren't adding up, and leads me to believe that my initial thoughts on connecting to a skimmer cup may be less about the recirculation reducing CO2, but more about vacuum.

The decrease % is less than the previous test and CO2 reduction is not noticeably different, but my pH has certainly increased. This is leading me to believe that recirculated air from the cup is less than the skimmer is trying to pull in creating a vacuum and an overall reduction in total air being skimmed.

I may drill an extra hole in the skimmer cup and see what happens.

 

[ShadowR55]

I'm going to have to look into a few things this weekend since some initial numbers aren't adding up, and leads me to believe that my initial thoughts on connecting to a skimmer cup may be less about the recirculation reducing CO2, but more about vacuum.

The decrease % is less than the previous test and CO2 reduction is not noticeably different, but my pH has certainly increased. This is leading me to believe that recirculated air from the cup is less than the skimmer is trying to pull in creating a vacuum and an overall reduction in total air being skimmed.

I may drill an extra hole in the skimmer cup and see what happens.

What kind of skimmer are you using? My Reef octopus has over 6 holes in the top

 

[JDowns]

What kind of skimmer are you using? My Reef octopus has over 6 holes in the top

Deltec 1000i

 

[Rostato]

I have noticed that the skimmer does seem to pull less air and is way harder to dial in. But I feel it’s worth it.

 

[ShadowR55]

Could possibly leave the lid cracked a little and put the hose down a little deeper? Maybe put some tape or something on the lip to keep the lid open a bit.

 

[JDowns]

Well I had already drilled two holes. Forgot about that. The Deltec has a internal wiper so you can spin the lid to clean the inside of the skimmer tube for cleaning. I had drilled two holes to make positioning the tube easier.

So that solves that question. There shouldn’t be a vacuum variable in the equation.

I’m going to recalibrate the sensors tomorrow.

In the beginning of each test ther has been a 60% or greater decrease in CO2. This test has started out at just under 50%. What gives me pause is the fact that pH has risen when it should be falling.

I have a lab CO2 handheld probe that I can take independent readings from the skimmer cup to verify things first.

Something is off that’s for sure.

 

[Mike220]

I tried purely outside air and I was only getting a PH of 8

Yes, same as me
Outside air to skimmer and get 8.02 max

 

[ShadowR55]

Well I had already drilled two holes. Forgot about that. The Deltec has a internal wiper so you can spin the lid to clean the inside of the skimmer tube for cleaning. I had drilled two holes to make positioning the tube easier.

So that solves that question. There shouldn’t be a vacuum variable in the equation.

I’m going to recalibrate the sensors tomorrow.

In the beginning of each test ther has been a 60% or greater decrease in CO2. This test has started out at just under 50%. What gives me pause is the fact that pH has risen when it should be falling.

I have a lab CO2 handheld probe that I can take independent readings from the skimmer cup to verify things first.

Something is off that’s for sure.

Interesting, I notice that when I connect the tube to my skimmer lid, the PH rises for a couple days and then it starts falling. The reactors will be full of condensation and then I disconnect it from the skimmer and go back to outside air after about a week and then my PH starts rising again as the moisture is used up in the reactor and it dries out. Did this a couple of times with the same results. Im just going to keep it using outside air for now and possibly connect a jar with water in it to keep the air somewhat humid, but I am in Florida and there is no shortage of humidity here anyway.

 

[JDowns]

Was able to isolate the problem.

The added tubing to run to the skimmer lid did create additional vacuum. I put a scope around all the connections and threads and found a pin hole leak where the wiring goes from the touchscreen into the sensor on the outlet side and inlet side. Once I plugged that with conduit putty the percentage decrease shot back up to over 70% and the inlet CO2 dropped.

I used a CO2 probe to check the CO2 levels at the skimmer cup and they are within the margin of error of the each sensor at the inlet side and the probe.

Amazing what a little pinhole leak can create.

 

[RamsReef]

Great stuff JDowns, I have had my skimmer scrubber hooked into my skimmer lid for a while now. The line is long enough and looped that water forms in the line and bubbles out, sort of like a water trap. This keeps it moist.

I find I go month before changing media, instead of 3-4 days when I was pulling from in the room.

Also, you guys may want to look up litholyme, this is what I am using.
http://litholyme.com/
http://litholyme.com/images/Litholyme_MSDS.pdf

 

[ShadowR55]

Great stuff JDowns, I have had my skimmer scrubber hooked into my skimmer lid for a while now. The line is long enough and looped that water forms in the line and bubbles out, sort of like a water trap. This keeps it moist.

I find I go month before changing media, instead of 3-4 days when I was pulling from in the room.

Also, you guys may want to look up litholyme, this is what I am using.
http://litholyme.com/
http://litholyme.com/images/Litholyme_MSDS.pdf

Litholyme pail is almost double the price of soda lime, does it work better?

 

[JDowns]

Great stuff JDowns, I have had my skimmer scrubber hooked into my skimmer lid for a while now. The line is long enough and looped that water forms in the line and bubbles out, sort of like a water trap. This keeps it moist.

Mine will do that also. I had to run the tubing in a way that any moisture would either drain back into the skimmer cup, or into the rice pre-scrubber. I need to run a rice pre-scrubber to keep condensation off of the inlet sensor otherwise the sensor will go into standby mode. I'm also keeping RO water in the bottom of the main scrubber to keep humidity up. The main part of the skimmer test is whether or not there is a significant difference in CO2 drop due to re-circulating the air.

I'll probably do this test again without a inlet sensor and only an outlet sensor and get rid of the rice pre-scrubber and see if there is a difference. I just won't be able to measure the incoming CO2 due to condensation. I'll let the inlet sensor run and just log ambient CO2 levels instead.

I'm not overly impressed with the first sensor enclosure design. So I worked up a prototype in CAD last night. I'll be using 1/2" NPT - 1/2" tube John Guest fittings for quick connections and so I can mount the sensor anywhere rather than right on the end of the scrubber. Also switch out the cabling to a more sealed design using a Binder 707 panel mount connector.

 

[RamsReef]

Dope, really cool.

 

[mitch91175]

Great stuff JDowns, I have had my skimmer scrubber hooked into my skimmer lid for a while now. The line is long enough and looped that water forms in the line and bubbles out, sort of like a water trap. This keeps it moist.

I find I go month before changing media, instead of 3-4 days when I was pulling from in the room.

Also, you guys may want to look up litholyme, this is what I am using.
http://litholyme.com/
http://litholyme.com/images/Litholyme_MSDS.pdf

Curious if it the media that allows you to go soo long without changing it. Going a month without changing media is insane. I get around a week or so and I have to change out media.

 

[JDowns]

Media longevity will be driven by two main factors. The humidity and the size of the skimmer, or more importantly how much air the skimmer is drawing.

I probably could have let the last test run another week before seeing a reasonable decrease in pH. So that would have been near a month before I needed to replace the media.

I'd be pretty happy with a month of usage and an average pH of 8.3. My nano in the same office runs an average pH of 7.9. Once the tests are done and I can repurpose the nano scrubber that will be going on the nano tank.

 

[Rostato]

I got a month out of my media easily. Even after changing my media I haven’t reach a ph over 8.35. I was hitting about 8.42 every day. I think the problem for e is that it’s winter and we don’t open windows or doors nearly as much.