A word of caution to those using CO2 scrubbers!!

[reefluvrr]

Moral of the story: If you are using a CO2 scrubber and the media seems depleted either change it very quickly or monitor ALK like a hawk to prevent any swings...

Thank you for the heads up.
I just installed my recirculating CO2 scrubber since last week. I noticed my ALK dropped from 7 dkh to 5.5 dkh after 3 days of running scrubber!
I had to up my neptune doser to compensate for the sudden increase in ALK demand. Did not think about the downside when PH drops back down and what would happen to alk levels then!!!
My pH before scrubber was from 8.1 to 8.3, after scrubber it is 8.3 to 8.5.

 

[ClearLife]

Regarding your scrubber depleting quickly, there are ways to mitigate that. You need to taylor your scrubber to your system and every system is different. You can run larger scrubbers, daisy chain multiple scrubbers together, and recirculate your Skimmer air back through the scrubber. Good luck, sorry this happened to you!

The best way to extend the life of your CO2 media, is to pull in fresh air from the outside instead of the CO2 rich air in the house. There is very little CO2 in fresh outside air.

 

[road_runner]

...

 

[DivingTheWorld]

The best way to extend the life of your CO2 media, is to pull in fresh air from the outside instead of the CO2 rich air in the house. There is very little CO2 in fresh outside air.

There can be problems with pulling from outside. You have to drill through your wall (if your tank is even near an outside wall), not to mention possible contaminants from outside (pesticides, fire smoke, etc.). In my case I just plumbed my scrubber to draw from my skimmer cup (credit @Bubbaque) so it recirculates the already skimmed air. On my system the media lasts 1.5+ months using a standard BRS scrubber.

For people who are worried about scrubbers depleting unexpectedly, I find the best solution (also credit @Bubbaque) is to daisy chain a couple together. As one is fully depleted, you just rotate the other forward and replace the depleted one. I don't personally use this method because my media lasts a crazy amount of time so there's no need.

 

[CMO]

The best way to extend the life of your CO2 media, is to pull in fresh air from the outside instead of the CO2 rich air in the house. There is very little CO2 in fresh outside air.

This is more of a replacement all together than a true life extension since it's just simply not being used all that much in this case. If you can plumb your skimmer to an external air source then you shouldn't need a scrubber at all. Also, as mentioned above, drilling through the house and running lines everywhere is pretty ridiculous. Not mention all the creatures and dust that can now get in your system from an open line to outside.

Here's a good thread with some pretty thorough testing of extending media. Simply connecting to the skimmer cup has proven to extend media for up to 2 months which are the results I'm seeing as well.

https://www.reef2reef.com/threads/co2-scrubber-testing.482361/page-6

 

[Nick13]

Like your setup!
I have a very similar Reef Octo skimmer, the neck cleaner, and a drain attached to an external skimmate collection vessel as it appears you do. What tool/method did you use to cut the hole in the skimmer cup? Looking to do the same without destroying my skimmer

 

[CMO]

Like your setup!
I have a very similar Reef Octo skimmer, the neck cleaner, and a drain attached to an external skimmate collection vessel as it appears you do. What tool/method did you use to cut the hole in the skimmer cup? Looking to do the same without destroying my skimmer

Thanks! You just need a drill bit made for plastics and go slow with light pressure to carve the plastic vs. drill it like wood. I've done 2 cups with this now with no issues at all. You can use a dremel with sanding drum to make the hole larger if 1/2" isn't large enough as it wasn't for me (or find a larger bit but that was challenging to find so I just got the 1/2" and used a dremel to finish. Here is the bit I used.

 

[Nick13]

Thanks CMO! Really looking forward to setting this up now!

Have you had any issues with excess moisture in your scrubber or reduced skimmer performance?
I would expect neither because a) even if the skimmer overflows, excess skimmate should normally just drain out to your skimmate collection vessel and b) the decomposition gases are moved away from the skimmer cup (as skimmate no longer accumulates here)

 

[vetteguy53081]

I believe Zero readings and treating it was not if help and I believe we see a case of chasing numbers which leads to casualty.
CO2 scrubbers have to be monitored but not known to kill.
It is always appreciated when one sends out a warning to others.

 

[CMO]

Thanks CMO! Really looking forward to setting this up now!

Have you had any issues with excess moisture in your scrubber or reduced skimmer performance?
I would expect neither because a) even if the skimmer overflows, excess skimmate should normally just drain out to your skimmate collection vessel and b) the decomposition gases are moved away from the skimmer cup (as skimmate no longer accumulates here)

Sure thing. No, in general I don't have any issue with excess moisture but I did add that down tube on the t fitting to collect the excess which is usually next to nothing. I run two float switches, one in my skimmer cup and one in the waste container so there little to no risk of issues with overflows.

 

[ClearLife]

I'm new to all this so please bare with me. Its my understanding from my research that CO2 in the water produces carbonic acid which gets neutralized by alkaline, Thus increasing the demand for alk. and can lower the PH if the alk is too depleted by the carbonic acid.
lowering the amount of CO2 in the water causes less carbonic acid produced and less alk load as a result of less load on alk. PH will likely rise as well. Where am I wrong?

 

[MnFish1]

I'm new to all this so please bare with me. Its my understanding from my research that CO2 in the water produces carbonic acid which gets neutralized by alkaline, Thus increasing the demand for alk. and can lower the PH if the alk is too depleted by the carbonic acid.
lowering the amount of CO2 in the water causes less carbonic acid produced and less alk load as a result of less load on alk. PH will likely rise as well. Where am I wrong?

Without going through all the chemistry - you're basically right - the more CO2 in the water the lower the pH - the less CO2 in the water the higher the pH.

 

[ClearLife]

Without going through all the chemistry - you're basically right - the more CO2 in the water the lower the pH - the less CO2 in the water the higher the pH.

Then why is Pete_the_Puma saying just the opposite and others are agreeing with him?

 

[MnFish1]

Then why is Pete_the_Puma saying just the opposite and others are agreeing with him?

I have no clue - and most people aren't agreeing with him

But the fact is - the more CO2 in the water the lower the pH - the less CO2 the higher the pH. Multiple people are discussing multiplethings - but the underlying concept is what I've described. I dont Know Pete the Puma - and I dont have time to read through multiple posts to see whether what he is saying makes sense. But - what I'msayingis true . If you agree great - if not - go ask Pete

 

[Pete_the_Puma]

We are all on the same page:

CO2 scrubbers reduce the CO2 inthe water increasing the pH which in turn leads to faster calcification of corals.

The issue and what I am warning people about is that most people will adjust for this higher alk demand by increasing daily dosing of ALK. Where the issue arises is when the CO2 absorbing media is depelted and not replaced quickly the ph falls down to prior levels and the ALK consuption goes back down, which in the face of continue high ALK dosing my lead to an Alakinity spike!

 

[MnFish1]

We are all on the same page:

CO2 scrubbers reduce the CO2 inthe water increasing the pH which in turn leads to faster calcification of corals.

The issue and what I am warning people about is that most people will adjust for this higher alk demand by increasing daily dosing of ALK. Where the issue arises is when the CO2 absorbing media is depelted and not replaced quickly the ph falls down to prior levels and the ALK consuption goes back down, which in the face of continue high ALK dosing my lead to an Alakinity spike!

If the Co2 scrubber (which it does) - reduces CO2 in the water - the alkalinity demand will 'fall' not rise. The amount of coral growth from a CO2 scrubber is probably not significant or? It certainly shouldn't be a rapid dangerous condition. Just like when you turn your air conditioner on and shut the windows - and the pH drops - its usually not a catastrophe. I think something else caused yoru problem.

 

[Pete_the_Puma]

There is ample evidence to suggest that a higher pH significantly increase coral calcification (and thus demand for alkalinity). See:

 

[CMO]

If the Co2 scrubber (which it does) - reduces CO2 in the water - the alkalinity demand will 'fall' not rise. The amount of coral growth from a CO2 scrubber is probably not significant or? It certainly shouldn't be a rapid dangerous condition. Just like when you turn your air conditioner on and shut the windows - and the pH drops - its usually not a catastrophe. I think something else caused yoru problem.

I can confirm that what @Pete_the_Puma said is absolutely true and confused by why you are saying a CO2 scrubber will reduce alk demand above which isn't true. My tank consumes a considerable amount more alk with the scrubber than without to the point that I absolutely will get an alk spike (if no change to dosing is made while media is left exhausted) as he describes if I don't replace the media to maintain ph before its exhausted.

CO2 scrubbers can absolutely have a BIG impact on PH and thus alk demand. My core 7 dose is about 20 ml different with and without a scrubber for reference.

 

[MnFish1]

I can confirm that what @Pete_the_Puma said is absolutely true and confused by why you are saying a CO2 scrubber will reduce alk demand above which isn't true. My tank consumes a considerable amount more alk with the scrubber than without to the point that I absolutely will get an alk spike (if no change to dosing is made while media is left exhausted) as he describes if I don't replace the media to maintain ph before its exhausted.

CO2 scrubbers can absolutely have a BIG impact on PH and thus alk demand. My core 7 dose is about 20 ml different with and without a scrubber for reference.

Its a degree right? Lets say I dont have a Co2 scrubber. I have the windows open in the spring - in May I close them and turn on the air conditioner - the pH drops some. Alkalinity is a buffer - it is 'designed' to help for these changes'. The pH change does not result in a catastrophe for the tank. Likewise pretend I have no Co2 scrubber - I have had my windows closed all summer with the AC on - and thus - the Co2 is higher. There is no disaster that happens when I open the windows in the fall - instead - the pH minimally changes etc etc. There is a difference in an
'ALK SPIKE' - I.e. - I add 500 cc of concentrated Sodium carbonate solution - and and alkalinity rise.

An alkalinity rise - such as what I described above will not harm coral or anything else. The OP is right one might have to turn down alk dosing - but even without that - its extremely unlikely to cause a major disaster (just like closing windows and opening them) does not.

We focus IMHO too much in this hobby on these very minor issues - when in reality - there are far more problematic issues with alk and Ca - most of which involve overdosing based on erroneous testing. again - My opinion.

 

[MnFish1]

There is ample evidence to suggest that a higher pH significantly increase coral calcification (and thus demand for alkalinity). See:

I was going to respond - but I decided not to - there are so many variables that go into this - that it is really not applicable to the discussion here. The discussion here is that there is an emergency if the CO2 scrubbier suddenly is exhausted.

To me the answer is - you have a piece of equipment on yoru tank - a Co2 scrubber. So maintain that equipment. The problem is not the Co2 scrubber running out of its chemical - its the aquarist that is using it not paying attention. To me (no offense) - the article shoudl be titled - make sure your Co2 scrubber has enough reagent to do its job. Otherwise - dont use a co2 scrubber