MCU Research CO2 Scrubber

[Kengar]

This unit is used to remove CO2 from the air going into your skimmer. Because CO2 makes up such a small percentage of the gas in air, I was skeptical but decided to try it out. Boy, was I impressed! I installed the unit last night. Tank is a 156, probably 170 g total system volume, and skimmer is a Bubble King mini 180. Draw is purported to be 2000 lph. Yesterday's pH max was 8.11 with 7.84 min the night before. Today topped out at 8.35, and you can see the whole graph (from AquaController III) trending upward:

 

[Boomer]

Ken

We have had two full threads on this unit here in the last week And nice graph.

 

[rbnice1]

this is the 3rd thread in the last 30 minutes in different forums.

Must really need to sell these I guess.

 

[Boomer]

The big debate issue is how long it will last before a refill.

 

[kaskiles]

Kengar, does your display tank and sump(s) receive a lot of air flow? Or are they covered, canopy over the display tank and sump(s) enclosed in cabinet?

 

[Randy Holmes-Farley]

It is an interesting graph. It looks to me as if you will have to back off on the effect soon or the pH may raise too far.

 

[Kengar]

I put the three posts in the three different forums I thought the information would be relevant to. Not trying to sell units for them; just impressed with the performance. I didn't go checking first to see if there were other threads, I just wanted to share information that I thought would be useful.

As for my setup, my tank is completely open-topped, and lighting fixture is suspended over it. I use fans blowing across the top of the water surface to control temperature by evaporative cooling. Sump is in the stand, which is open-backed, and I have a fan running full time in the cabinet to circulate air in there.

I should also add that I run two Ca reactors in tandem, with output from one being input to next, but with CO2 only into first. Essentially a dual-chamber configuration, but with recirculation in the downstream chamber, too. Four seconds between CO2 bubbles. Haven't checked effluent parameters yet (pH, Ca, and alk) yet, though.

As for seeing the graph continue to shift, although I think Randy's post was tongue-in-cheek, I don't think thiat is a concern. Rather, I believe the system will simply move to a new equilibrium level, with pH rising and falling around that new level.

 

[kaskiles]

I would have expected the gas exchange with the un-stripped air (high CO2) at the water surface of the DT and sump would have exceeded that of the skimmer, and the pH increase to be much less pronounced. But your results seem to indicate otherwise... I was also worried that it might decrease the air draw of the skimmer, and possibly affect it's performance.

Please keep us updated on the consistency of these pH results, lifespan of the media and skimmer performance changes.

Thanks!

 

[Kengar]

I was concerned re decreased draw into skimmer, too. Per conversation wtih Premium Aquatics, though, MCU redesigned their original system to avoid/minimize additional drag. I haven't seen any noticeable performance change in the skimmer in terms of bubbles/foam, but that would really be hard to quantify, and I haven't really had enough time to see whether skimmate output falls. However, I believe one of the primary reason skimmers aren't used in freshwater systems is that the bubbles collapse under low pH conditions, so conversely raising pH may improve bubble stabiliyt in saltwater and hence improve performance, at least by enough to offset any decrease caused by reduced air intake. Final observation: I see my BTA's actually bubbling out again this a.m., which they haven't done in a while.

 

[Randy Holmes-Farley]

As for seeing the graph continue to shift, although I think Randy's post was tongue-in-cheek, I don't think thiat is a concern. Rather, I believe the system will simply move to a new equilibrium level, with pH rising and falling around that new level.

It likely would reach a new range, but the graph doesn't indicate that yet. There is certainly no theoretical reason such a device couldn't drive pH too high, just like dosing limewater.

 

[Boomer]

freshwater systems is that the bubbles collapse under low pH conditions

It has to due with surface tension and water hardness. The harder the water the more skimming there will be and this also includes the nature of the organics in FW vs hard water. Think of when you are in a bath or shower, where one house/ motel etc, has hard water and the other soft water and the difference you see when you lather yourself up with soap.

This goes into greater detail

What is Skimming?
http://reefkeeping.com/issues/2006-08/rhf/index.php

In regards to your pH. As Randy has stated yes it can get to high. You will see this in heavy planted aquariums, be it FW or SW, where the pH can it over 9 pH. And all from what, the Algae or plants pulling out the CO2 just like the scrubber or limewater. @ 25 C, 35 ppt, 2.5 meq / l Alk, a pH of ~ 10.5 must be reached to have zero CO2

 

[Kengar]

I thought that surface tension varied with pH. Probably varies with a whole host of factors! I will take the caution re pH going too high to heart and watch it. I'll give the syystem a few days to stabilize at full capability of the scrubber and post further graph to show where it stands.

 

[Boomer]

Yes, a whole host of factors. Just stick your hand in the tank near the skimmer input and watch the skimming go about flat or put a drop of aloe-vera in it and watch it go nuts.

Also see my edit.

 

[Kengar]

and the difference you see when you lather yourself up with soap.

I'm supposed to use soap?

 

[Boomer]

I add Tide once a day

 

[Kengar]

Whoops! I deleted the original graph showing the rise in pH from my photobucket account. Here it is again:

a few days later, the increased pH is holding steady (lights left on a little longer tonight, which is why the peak is sustained)

 

[Boomer]

Good to hear Kengar :thumbsup:

 

[Randy Holmes-Farley]

Looks good!

 

[Kengar]

hmmmmm, two weeks later and pH has dropped about 0.2 overall. Not sure whether the GFO dust had something to do with it when I fired up a fresh batch for phosphate filtration, since the drop seemed to coincide with that. Putting in a fresh cartridge tonight; will see how long that lasts.

 

[Boomer]

Well, Jeremy from PA told me at MACNA his media in his test lasted like 2 weeks. It may have been the dust. Check the Alk and Ca++ and see if it has dropped.