TRYING TO RAISE pH BY REDUCING CO2 FROM CALCIUM REACTOR

[Dr. Jim]

I'm hoping reefers with a chemistry background might comment on my ideas to lower CO2 in the Ca reactor effluent (pH 6.4).
Tank pH: 7.4-7.8; Outside air is plumbed to protein skimmer.

I'm considering abandoning the Ca reactor and going back to dosing 2-Part, but it would be a shame to do away with a nice Deltec Ca reactor. For now, I have reduced the reactor effluent from 84 L/day to 42L/day and started dosing some 2-Part to maintain alkalinity around 8.

I have 2 ideas to discuss:

A. Flow effluent through a gallon jug of A.R.M. reactor media. I could drill holes in the bottom and let the effluent flow through from the top.
Question: Does it matter if the A.R.M. container is submersed in the sump or does it need to be above the water line? I believe it shouldn't matter for the chemical reaction between the CO2 and the media. But, it might be beneficial to be out of the water so CO2 can escape into the air.
Does this make sense, and do you think there would be a significant advantage to have it above the water level?
(I'm asking because it might be easier to set it up submersed and I'm not sure if the Deltec will work properly if the effluent tube is raised which might be necessary if the A.R.M. container is above the water line but I can play around with this if it is decided to be better above the water level.)

B. Collect the effluent coming from the A.R.M. jug with a funnel (assuming it is above the water level of the sump) and connect a tube to the funnel and feed it into the protein skimmer pump uptake.
Question: Will this be helpful to reduce CO2 and will it cause the skimmer to be less efficient? I'm thinking that there should be no change to the efficiency of the skimmer because I don't think the gas content of the bubbles makes a difference when it comes to adsorbing protein, correct? And, I'm thinking excess CO2 may be removed by the skimmer. Agree?

Thank you for your thoughts.

 

[Randy Holmes-Farley Verified Community Expert]

Passing the effluent over more media will allow you to get the most out of the CO2 you are adding, but it does not eliminate the pH reducing effect of the CO2 that is added.

Sending it through a skimmer may or may not allow more CO2 to blow off. Its now a high alk fluid so holds more CO2.

 

[Dr. Jim]

Passing the effluent over more media will allow you to get the most out of the CO2 you are adding, but it does not eliminate the pH reducing effect of the CO2 that is added.

Would you mind elaborating and explaining this? Wouldn't more CO2 being used to produce more alk and Ca (from the additional A.R.M. chamber) reduce the amount of CO2 entering the tank which would in turn reduce the "pH lowering effect"? (i.e. less C02 = less pH lowering)
Thank you, Randy.

 

[Biff0rz]

I have a secondary chamber on my CaRx output, before I didn't. The pH net result is very little, if any. I think it maybe improved by 0.05. I've found a lot of increased pH by adding Kalkwasser and adding a co2 scrubber. The co2 scrubber, by far, has made a huge difference. The only down side to it is the media is expensive and you burn through it quickly during certain seasons

 

[Dr. Jim]

I have a secondary chamber on my CaRx output, before I didn't. The pH net result is very little, if any. I think it maybe improved by 0.05. I've found a lot of increased pH by adding Kalkwasser and adding a co2 scrubber. The co2 scrubber, by far, has made a huge difference. The only down side to it is the media is expensive and you burn through it quickly during certain seasons

I do use the maximum amount of Kalk by passing top-off water thru a kalk reactor.
I also have a two-chamber C02 chamber but don't replenish it as often as I should and will probably remove it.
I'm more interested in trying to reduce the pH lowering effect of the Ca reactor.
Thanks!

 

[Biff0rz]

I do use the maximum amount of Kalk by passing top-off water thru a kalk reactor.
I also have a two-chamber C02 chamber but don't replenish it as often as I should and will probably remove it.

I change my scrubber material every 2-3 weeks.

I'm more interested in trying to reduce the pH lowering effect of the Ca reactor.
Thanks!

you'll have to take it offline. The nice thing about a CaRx is not having to buy/mix/make/etc 2-part. The downside is the higher co2. That said, 7.8 isn't that low. Are you fish heavy? Lots of fish and critters increases co2 too, and obviously environment (closed house, lots of people/animals, etc)

 

[Jamie814]

Sending it through a skimmer may or may not allow more CO2 to blow off. Its now a high alk fluid so holds more CO2.

I’ve seen people do something similar without using the skimmer. They drip the effluent into a separate container with an air pump and air stone, then let it drip from there into the sump. It definitely helps raise the pH, by driving off excess CO₂ but there’s a tradeoff. Since the effluent is highly saturated with calcium and alkalinity, raising the pH can cause precipitation, which drops the dKH of the effluent quite a bit.

Does this make sense, and do you think there would be a significant advantage to have it above the water level?

This really is no different than adding a 2nd chamber to your reactor, it does help....a tiny bit. BRS did a video on it a while back.

 

[Randy Holmes-Farley Verified Community Expert]

Would you mind elaborating and explaining this? Wouldn't more CO2 being used to produce more alk and Ca (from the additional A.R.M. chamber) reduce the amount of CO2 entering the tank which would in turn reduce the "pH lowering effect"? (i.e. less C02 = less pH lowering)
Thank you, Randy.

If you do not open up the valve more, then an extra chamber is not causing more CO2 to flow into the system.

But allowing the existing CO2 to contact media longer dissolves more calcium carbonate (unless it has already hit saturation for that pH), but also does not send any less CO2 into the system.

ALL of the CO2 added ends up in the tank (unless you blow some off first) regardless of whether it helps dissolve more calcium carbonate or not.

In a sense, the CO2 is just facilitating the dissolution. It is not being permanently consumed.

 

[Dr. Jim]

That said, 7.8 isn't that low.

The fish aren't complaining but 7.6-7.8 is way too low for good growth for SPS (which is what I care about). I've always been able to maintain 8.0-8.2. I'm wondering if my relatively new Deltec is using more CO2 than my former more conventional GEO reactors.

 

[Dr. Jim]

Another way in which the additional A.R.M. chamber can help is simply by producing more alk and Ca while using the same amount of CO2 which would allow me to reduce the flow rate of effluent which in turn reduces the amount of CO2 introduced.
I'll work on this and report back...
Thanks everyone!

 

[Biff0rz]

The fish aren't complaining but 7.6-7.8 is way too low for good growth for SPS (which is what I care about). I've always been able to maintain 8.0-8.2. I'm wondering if my relatively new Deltec is using more CO2 than my former more conventional GEO reactors.

If your alk levels/stability haven't changed, I would think not. How are you monitoring your alk? I dont think changing reactors change the chemistry of what happens all that much, so my guess is maybe you're outputting more than before? I am not a fan of the deltec reactors, expensive and they have issues after a few years. My geo has been rocking solid.

 

[JonasRoman]

This is same as just have a larger reactor=increase contact time between same amount of dosed CO2 to CaCO3.

I think I understand how you thinking, that if one mole CO2 is reacting completely with one mole CaCO3 we only get hco3 and Ca on the right side of the reaction. BUT: we need an excess of CO2 to make this happen due to low solubility of CaCO3. Thus means that if we wants CaCo3 to dissolve we must overdose CO2 so its always besides the produced Ca and Hco3, also is excess of non reacted CO2. So its impossible to consume the excess CO2 as when CO2 is too low it will not be able to dissolve CaCo3 and then just be still in solution as CO2. Do you dose too little Co2 to avoid excess then most of this with just pass unreacted as CaCo3 is then not dissolved.
So, to get reactor work it must be an excess and if/when co2 is that low so it cant further dissolve caco3, then no further absorption of Co2 may occur. This is an schematic way of explaining , and Randy may have a better explanation:-)

I would instead solve the issue from the root: let air to skimmer go through a CO2 absorbing media.

 

[iani]

Look into getting a erv for your house. I think this will make the biggest improvement in your tank ph.

 

[Biff0rz]

Look into getting a erv for your house. I think this will make the biggest improvement in your tank ph.

My reefer friend spend 5k on one (unit+install) and it didn't do much. I've wanted to do this but man, thats a lot to pay if it doesn't work...

 

[Dr. Jim]

Thank you all for your responses but I would just like to reiterate that the intent of this thread is not to discuss ways to raise the pH of the tank but rather how to diminish the "pH-lowering effect" of CO2 from a calcium reactor. My conclusion is that the best I can do is pass the effluent through an additional chamber of Ca reactor media to produce more alkalinity and calcium which in turn will allow me to lower the volume of effluent from the reactor (which in turn lowers the amount of CO2 being introduced). I will then pass the final effluent thru my skimmer in hopes of that helping as well.

Although I love the Deltec calcium reactor for its ingenious design and ease of use, I do have reason to believe that it requires more CO2 than a conventional reactor.

 

[iani]

My reefer friend spend 5k on one (unit+install) and it didn't do much. I've wanted to do this but man, thats a lot to pay if it doesn't work...

Maybe its not big enough?

 

[iani]

Thank you all for your responses but I would just like to reiterate that the intent of this thread is not to discuss ways to raise the pH of the tank but rather how to diminish the "pH-lowering effect" of CO2 from a calcium reactor. My conclusion is that the best I can do is pass the effluent through an additional chamber of Ca reactor media to produce more alkalinity and calcium which in turn will allow me to lower the volume of effluent from the reactor (which in turn lowers the amount of CO2 being introduced). I will then pass the final effluent thru my skimmer in hopes of that helping as well.

Although I love the Deltec calcium reactor for its ingenious design and ease of use, I do have reason to believe that it requires more CO2 than a conventional reactor.

I run a calcium reactor and do not have an issue with pH.

 

[JonasRoman]

Thank you all for your responses but I would just like to reiterate that the intent of this thread is not to discuss ways to raise the pH of the tank but rather how to diminish the "pH-lowering effect" of CO2 from a calcium reactor. My conclusion is that the best I can do is pass the effluent through an additional chamber of Ca reactor media to produce more alkalinity and calcium which in turn will allow me to lower the volume of effluent from the reactor (which in turn lowers the amount of CO2 being introduced). I will then pass the final effluent thru my skimmer in hopes of that helping as well.

Although I love the Deltec calcium reactor for its ingenious design and ease of use, I do have reason to believe that it requires more CO2 than a conventional reactor.

I think you still think a little incorrect. Your modulation is same as,have a larger reactor=more media. So think larger reactor, snd that will not give less co2 to the tank because you must increase CO2 dose to match more media. If you have samw co2 but increase media (its actually what you do with your test) you will dissolve less CaCo3 as now you underdose CO2,meaning you will release same amount of CO2 to water as before.

You want to reduce the pH lowering effect of CO2(its not of any importance where it comes from) =let tank breath out more CO2=CO2 absorber on the intake air to skimmer. No other ways will work (and algue refugium is also same effect but more complicated thst CO2 absorber)

 

[A_Blind_Reefer]

Maybe use Diet Co2, or Co2 Zero?