TRYING TO RAISE pH BY REDUCING CO2 FROM CALCIUM REACTOR

[Dr. Jim]

You are correct! It’s essential a downdraft skimmer in design.

From first pic on the right is the feed line tied off return pump. Gate valve to adjust flow rate. Water enters at the top of the chamber. Drain line is left side at bottom. Emergency drain is in the middle.

Black air line tubing drops in from top down to a 12” alita air stone.

The amount of air is adjusted from a bleed valve up top by pump to the max output adjustment without causing issues.

So you introduce outside/lower co2 air. Adjust water flow rate through it while monitoring ph to achieve required contact time for the max ph boost from removing co2. The Airstone bubbles will rise to the top of the chamber/reactor, bubble, off gas and flow out the top to be vented out.

I understand the concept but not sure if I understand the plumbing (but won't ask you to explain). I'll read rishma's thread with hopes that that will explain it. Thank you, @jonelder68, for posting the link.

In an earlier thread I mentioned that I recently added more fish so now I can finally stop dosing PO4 and NO3 but need to start exporting it so will set up an algae reactor fed by effluent from the CaRx. Here's a video of my fish; half of them were added a couple of months ago. In quarantine, and soon to be added, are: a Copperband, 5 fairy wrasses, multibar angel and a lyretail anthias. (Only 1 of 6 anthias survived unfortunately). I know they will be crowded when they all grow up but in about a year they will be moved from my IM 200EXT to a tank twice the size.

 

[jonelder68]

I understand the concept but not sure if I understand the plumbing (but won't ask you to explain). I'll read rishma's thread with hopes that that will explain it. Thank you, @jonelder68, for posting the link.

In an earlier thread I mentioned that I recently added more fish so now I can finally stop dosing PO4 and NO3 but need to start exporting it so will set up an algae reactor fed by effluent from the CaRx. Here's a video of my fish; half of them were added a couple of months ago. In quarantine, and soon to be added, are: a Copperband, 5 fairy wrasses, multibar angel and a lyretail anthias. (Only 1 of 6 anthias survived unfortunately). I know they will be crowded when they all grow up but in about a year they will be moved from my IM 200EXT to a tank twice the size.

If you have any questions feel free to ask. Tonight was the first trial run and was not great! For sure too much air pump. It’s in trial and error stage so once I get it dialed in I’ll add to rishmas thread or start another to update. Rishma’s concept was on a way smaller scale but we’re trying to enlarge it but getting it just right might take some trial and error/redos

 

[steveweast]

I also run a Deltec CaRx. I have found that running the effluent through the skimmer helps a little....but not much. The dwell time is just too short. Water is in...and out....of the skimmer quickly. Same goes with running through algae....dwell time is just too short to make a difference. I tried a second media chamber too...that didn't help much either.

What did give my tank an immediate .1 pH bump of the highs and lows was when I created an off-gassing chamber in my sump. The only water that flows into this chamber is from the reactor. A little flows in....and then a little flows out back into the sump. The dwell time is now very, very long. The aeration is created by a generic skimmer pump in the bottom of the chamber.

 

[Jamie814]

The only water that flows into this chamber is from the reactor. A little flows in....and then a little flows out back into the sump. The dwell time is now very, very long. The aeration is created by a generic skimmer pump in the bottom of the chamber.

How long have you been running the system this way, and are you observing any calcium carbonate precipitation in the effluent chamber? Since the effluent has such high alkalinity and calcium concentrations, raising its pH should also increase the potential for precipitation. It seems like some of that calcium and alkalinity should precipitate out before the effluent ever reaches the aquarium.

Have you tired doing a recirculation loop with a co2 scrubber on that skimmer pump?

 

[Dr. Jim]

I also run a Deltec CaRx. I have found that running the effluent through the skimmer helps a little....but not much. The dwell time is just too short. Water is in...and out....of the skimmer quickly. Same goes with running through algae....dwell time is just too short to make a difference. I tried a second media chamber too...that didn't help much either.

What did give my tank an immediate .1 pH bump of the highs and lows was when I created an off-gassing chamber in my sump. The only water that flows into this chamber is from the reactor. A little flows in....and then a little flows out back into the sump. The dwell time is now very, very long. The aeration is created by a generic skimmer pump in the bottom of the chamber.

This is very interesting and useful information! Thank you!
Where and how does the effluent enter the chamber and where does it exit?
Is the tray on the top holding activated carbon?

I wonder why this system would work better than a protein skimmer (assuming the same number of bubbles and contact time, or water depth, is the same). I understand that the flow through it is much slower but if the number of bubbles in each system (a conventional skimmer vs yours) is the same, it would seem that the CO2 reduction should be the same. With the skimmer, water passes through faster but it is also processing CO2 from the main tank. But, if you tried both systems, and the dedicated degasser works best, I suppose that's the one to use!
I definitely want to build one.
Thanks!

 

[Dr. Jim]

I also run a Deltec CaRx.

Do you think the Deltec uses more CO2 than a conventional "CO2 bubble-counter" skimmer? I burned through my first CO2 tank very quickly but part of that may have been due to a learning curve. I'm doing better with the 2nd tank but still have reason to believe it is going faster. I have doubled the degassing time to reduce CO2 introduction, just in case that might help, but I still suspect greater CO2 usage. If this is true, it is a real shame because, otherwise, I love the Deltec design and functionality!

 

[steveweast]

My Bubble King skimmer has about 2000 GPH running through it. That contact time is tiny. The gas chamber just has the effluent entering and exiting....so that contact time could be hours or days. I have been running the gas chamber for about 4 years now. I tried all the usual ways to reduce the effluent CO2...and this had the most impact. I have not noticed any precipitation. Although, since I do monthly water changes by emptying my entire sump and cleaning it, maybe it just doesn't build up.

The black component on top of the reactor is just a black sponge and allows air to escape but prevents bubble spray and salt creep.

Basically, this gas exchange reactor is just a low volume skimmer. The supply air for both my skimmer and reactor is outside ambient air.

 

[steveweast]

Do you think the Deltec uses more CO2 than a conventional "CO2 bubble-counter" skimmer? I burned through my first CO2 tank very quickly but part of that may have been due to a learning curve. I'm doing better with the 2nd tank but still have reason to believe it is going faster. I have doubled the degassing time to reduce CO2 introduction, just in case that might help, but I still suspect greater CO2 usage. If this is true, it is a real shame because, otherwise, I love the Deltec design and functionality!

I cannot really say for sure how the Deltec compares with others on CO2 usage since I've only run the Deltec since 2020. I believe that its reaction chamber runs a higher CO2 concentration than others might though. I still think it's the most user friendly reactor out there since it only has one variable....which is how much effluent do you want. You just have to deal with the residual CO2 in some manner. Really....the effluent from every calcium reactor needs to be dealt with....just more with the Deltec. I find that a workable trade-off to get the ease of use.

I also do not think that any one solution is the be all end all. I also employ other methods for pH control as well....it's a team effort. It's just the gas exchange reactor's contribution is a .1 boost. Here is what else I do...

1) my tank is in a constantly ventilated garage so ambient CO2 is as low as possible all the time.
2) I dose NaOH and KOH at night to offset the pH drop.
3) my Bubble King's skimmer air intake first goes through soda lime.
4) evaporation make up is kalkwasser at night.

This is a snapshot of my current readings. My low pH never drops below 8.3.

 

[steveweast]

One more thought....I also employ other Alk additions along with my reactor. I dose kalk at night to replace all evaporation and dose NaOH/KOH at night too. These contribute as well to provide Alk. My Deltec reactor is currently set to provide 14 liters per day....a relatively low number and well below its capacity. All of these contribute to maintain my morning Alk reading of 8.0. Right now, my 10lb CO2 tank is good for about 2-2/12 months.

The reactor is how I adjust the tank's Alk though. I just need to dial it up or down to maintain 8.0 on the morning reading.

 

[Boxed Fish]

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.

what is your skimmer connected to? if nothing you can add a reactor with kalkwasser co2 media. me personally I add sodium hydroxide crystals inside of a fine mesh bag, then place into the reactor, connected to my skimmer. more equipment for you if you have the room but simplest way is to aerate the water in that section of the sump with a high powered air pump to burn off co2 as quickly as possible

 

[Dr. Jim]

One more thought....I also employ other Alk additions along with my reactor. I dose kalk at night to replace all evaporation and dose NaOH/KOH at night too. These contribute as well to provide Alk. My Deltec reactor is currently set to provide 14 liters per day....a relatively low number and well below its capacity. All of these contribute to maintain my morning Alk reading of 8.0. Right now, my 10lb CO2 tank is good for about 2-2/12 months.

The reactor is how I adjust the tank's Alk though. I just need to dial it up or down to maintain 8.0 on the morning reading.

Wow....my Deltec has been on 80-100 L/day. I recently reduced it to 35 and started 2-Part.
How long does your tank last? 2-2/12 months? (Is that 2 to 2.5 months?)

 

[Dr. Jim]

what is your skimmer connected to? if nothing you can add a reactor with kalkwasser co2 media. me personally I add sodium hydroxide crystals inside of a fine mesh bag, then place into the reactor, connected to my skimmer. more equipment for you if you have the room but simplest way is to aerate the water in that section of the sump with a high powered air pump to burn off co2 as quickly as possible

I have a separate Kalk stirrer connected to top-off water float valve.
I do use outside air that passes thru carbon, then CO2 media. I need to look into NaOH and KOH. (Do they raise Na and K significantly?)

 

[Boxed Fish]

I have a separate Kalk stirrer connected to top-off water float valve.
I do use outside air that passes thru carbon, then CO2 media. I need to look into NaOH and KOH. (Do they raise Na and K significantly?)

it doesn't raise potassium has no affect on that but NA yes. liquid mixture would be 28g/500ml. I use it in liquid and dry form. during the day liquid and over night dry form through the reactor just allowing air to pass through and around it. if you use dry form make sure its in a mesh bag as once its spent it will harden like a rock so you want to be able to remove it. so make like fingers or ball sized bags for easy removal depending on the size and shape of reactor

 

[steveweast]

Wow....my Deltec has been on 80-100 L/day. I recently reduced it to 35 and started 2-Part.
How long does your tank last? 2-2/12 months? (Is that 2 to 2.5 months?)

Yes...my cylinder lasts about 10 weeks. My system is 400 gals and packed with SPS. I find it odd that you need that much production out of your reactor. That's a tall order to deal with that much effluent. What media are you using? Reborn? Reborn seems to dissolve easily....others like ARM are harder to dissolve.

 

[Dr. Jim]

Yes...my cylinder lasts about 10 weeks. My system is 400 gals and packed with SPS. I find it odd that you need that much production out of your reactor. That's a tall order to deal with that much effluent. What media are you using? Reborn? Reborn seems to dissolve easily....others like ARM are harder to dissolve.

I've been using the Deltec media. Circulation set on 45. Degas set on 100 or more

 

[jda]

If your CaRx is dropping tank pH, then you have too much unused co2 escaping the reactor. This is very common in pump-and-dump type of setups where a co2 controller turns a regulator on/off and dumps in excessive co2 in batches, like a sine wave. Best thing to do is to tune the CaRx to put in steady output with a dKh around 25 all of the time. I used to go through a 50 lb bag of media and 20lb of co2 a few times a year. There is an old article in a google doc in my signature that explains how to tune a CaRx - lifetime skill worth learning.

Otherwise, the best way to raise tank pH is to keep your home low on co2. Before you spend money on anything else, get an indoor co2 meter with a NDIR sensor (must be NDIR) and see where you are at - like a $50-75 one so that it lasts a long while. With a CaRx pumping through so much media and co2, if my indoor co2 was under 600, my tank pH would be around 8.3. Don't be a fool and sweat pennies of natural gas or electricity to open windows or doors every once in a while versus hundreds or thousands to buy soda lime, equipment or whatever. If co2 is high enough in your home to affect the tank, humans and pets will benefit from more fresh air too. Remember, you just need to exchange air, not cool down or heat up a house - a few minutes can do this so think of it as cracking the window in a car to let out your Uncle's nasty fart where nobody actually gets cold, but the air is all exchanged.

Get a co2 monitor before you do anything else. Mine says 528 right now, which is the room that I am in - probably 50-75 less in the basement near the tank.

 

[Dr. Jim]

If your CaRx is dropping tank pH, then you have too much unused co2 escaping the reactor. This is very common in pump-and-dump type of setups where a co2 controller turns a regulator on/off and dumps in excessive co2 in batches, like a sine wave. Best thing to do is to tune the CaRx to put in steady output with a dKh around 25 all of the time. I used to go through a 50 lb bag of media and 20lb of co2 a few times a year. There is an old article in a google doc in my signature that explains how to tune a CaRx - lifetime skill worth learning.

Otherwise, the best way to raise tank pH is to keep your home low on co2. Before you spend money on anything else, get an indoor co2 meter with a NDIR sensor (must be NDIR) and see where you are at - like a $50-75 one so that it lasts a long while. With a CaRx pumping through so much media and co2, if my indoor co2 was under 600, my tank pH would be around 8.3. Don't be a fool and sweat pennies of natural gas or electricity to open windows or doors every once in a while versus hundreds or thousands to buy soda lime, equipment or whatever. If co2 is high enough in your home to affect the tank, humans and pets will benefit from more fresh air too. Remember, you just need to exchange air, not cool down or heat up a house - a few minutes can do this so think of it as cracking the window in a car to let out your Uncle's nasty fart where nobody actually gets cold, but the air is all exchanged.

Get a co2 monitor before you do anything else. Mine says 528 right now, which is the room that I am in - probably 50-75 less in the basement near the tank.

Nice to hear from you, @jda!

I did order a CO2 (NDIR) yesterday, but I doubt my home CO2 is high. It's just my wife and I and am now in N.C. where windows are open a lot. Aquarium is in den right next to front door which opens frequently. Also, I have half inch tubing coming in from outside to skimmer.

I think the culprit may be my Deltec CaRx. Not sure if you are familiar with that one, but you can't adjust the CO2 intake. The only thing you can adjust is the L/day effluent. I do have reason to believe the Deltec burns thru more CO2 than conventional Ca reactors. Also, the Deltec media is very hard, large calcite rocks and they may require more CO2 compared to other brands as @steveweast alluded to in post #49. His tank is twice the size of mine loaded with SPS and his Deltec is set at 14 L/day while mine is at 90+ L/day!

As an experiment, I am gradually converting back to 2-part (and lowering my CaRx effluent) until I temporarily stop the CaRx completely to see if the reactor is the culprit. If so, I will switch media to Newborn and see if I can get by with much less effluent.

I had a VarioS-4 skimmer pump (draws 1500 LPH air) kicking around so I thru it into the sump yesterday. Today, the pH was a bit higher (by 0.06 -0.1). In 2 days, I will have a plumbing part to tie it into my outside air tube. Will report back later.

Thanks for helping!

 

[jda]

Nice to hear from you, @jda!

I did order a CO2 (NDIR) yesterday, but I doubt my home CO2 is high. It's just my wife and I and am now in N.C. where windows are open a lot. Aquarium is in den right next to front door which opens frequently. Also, I have half inch tubing coming in from outside to skimmer.

I think the culprit may be my Deltec CaRx. Not sure if you are familiar with that one, but you can't adjust the CO2 intake. The only thing you can adjust is the L/day effluent. I do have reason to believe the Deltec burns thru more CO2 than conventional Ca reactors. Also, the Deltec media is very hard, large calcite rocks and they may require more CO2 compared to other brands as @steveweast alluded to in post #49. His tank is twice the size of mine loaded with SPS and his Deltec is set at 14 L/day while mine is at 90+ L/day!

As an experiment, I am gradually converting back to 2-part (and lowering my CaRx effluent) until I temporarily stop the CaRx completely to see if the reactor is the culprit. If so, I will switch media to Newborn and see if I can get by with much less effluent.

I had a VarioS-4 skimmer pump (draws 1500 LPH air) kicking around so I thru it into the sump yesterday. Today, the pH was a bit higher (by 0.06 -0.1). In 2 days, I will have a plumbing part to tie it into my outside air tube. Will report back later.

Thanks for helping!

Above 700 or 800 ppm of co2 in the house, which is about where schools and office buildings are supposed to keep the co2, I could see a pretty sharp decline in tank pH. Keep in mind that ocean acidity has raised 25-30% since the industrial revolution when the atmospheric co2 raised about 100 ppm... so a little matters a lot a the low end.

I know that the Deltec does not use a ph probe or pump and dump, but I have not known anybody who could get it as efficient as hand tuning something like a Korallin or other type of design. My theory is that the surface area of the co2 bubble would need to expand or contract with the flow through the reactor to have be perfectly efficient - the same surface area with 90L a day cannot possibly be absorbing the same co2 as with 14L a day. Basically, you always have too much surface area and exposure to co2. Besides, I have no idea why L/day means anything if you don't know the dKh of the effluent is. What is yours? It would seen to me that if you up the input to the Deltec, then the exposure time to the co2 would drop and your dKh would go down - it is not like there is infinite surface are for co2 to make contact with the water. Less could be more. I find about 25 dKh to be perfect. 30 or 35 is fine, but 25 give some leeway. Just turn your ratio up and keep it at 25. 25 also seems to be where there is the last amount of co2 that gets into the tank and maximum tank pH. I could melt (I know that it is actually dissolving) a whole chamber of natural media in two months in a Korallin 1000 at 25 dKh.

As for media, it does not matter in a well tuned reactor. The cylinder pH is all that changes. If the reactor is well tuned, then no/little co2 leaves the chamber and it does not matter what the effluent pH is at all. I used man-made media for a while there when natural was hard to find (and my stash ran out), but the tank pH did not move even though I had to up the co2 to get the reactor pH lower, but it was still tuned well.

 

[Dr. Jim]

Above 700 or 800 ppm of co2 in the house, which is about where schools and office buildings are supposed to keep the co2, I could see a pretty sharp decline in tank pH. Keep in mind that ocean acidity has raised 25-30% since the industrial revolution when the atmospheric co2 raised about 100 ppm... so a little matters a lot a the low end.

I know that the Deltec does not use a ph probe or pump and dump, but I have not known anybody who could get it as efficient as hand tuning something like a Korallin or other type of design. My theory is that the surface area of the co2 bubble would need to expand or contract with the flow through the reactor to have be perfectly efficient - the same surface area with 90L a day cannot possibly be absorbing the same co2 as with 14L a day. Basically, you always have too much surface area and exposure to co2. Besides, I have no idea why L/day means anything if you don't know the dKh of the effluent is. What is yours? It would seen to me that if you up the input to the Deltec, then the exposure time to the co2 would drop and your dKh would go down - it is not like there is infinite surface are for co2 to make contact with the water. Less could be more. I find about 25 dKh to be perfect. 30 or 35 is fine, but 25 give some leeway. Just turn your ratio up and keep it at 25. 25 also seems to be where there is the last amount of co2 that gets into the tank and maximum tank pH. I could melt (I know that it is actually dissolving) a whole chamber of natural media in two months in a Korallin 1000 at 25 dKh.

As for media, it does not matter in a well tuned reactor. The cylinder pH is all that changes. If the reactor is well tuned, then no/little co2 leaves the chamber and it does not matter what the effluent pH is at all. I used man-made media for a while there when natural was hard to find (and my stash ran out), but the tank pH did not move even though I had to up the co2 to get the reactor pH lower, but it was still tuned well.

The dKh coming out of the Deltec is about 38; pH is 6.0. For those that don't know, the Deltec does not allow you to control the amount of CO2 going into it. There is a separate cylinder, about 1.5" in diameter with a float valve. The bottom several inches contain CO2 gas, the rest of the chamber is water (above the gas). As CO2 is used up, the float valve falls and triggers the input of more gas. The only thing that can be controlled is the L/day of effluent. It is an ingenious design and very easy to use, (but if 38 dKh is too high and detrimental, then maybe this reactor isn't the best?) But, I suspect the type of media may make a difference. If it is true that some, like Reborn, dissolve more quickly than the Deltec calcite, it may be that the effluent volume/day can be greatly reduced, thereby introducing less CO2 into the tank. As mentioned, I plan to try the Reborn soon.

 

[jda]

The dKh coming out of the Deltec is about 38; pH is 6.0. For those that don't know, the Deltec does not allow you to control the amount of CO2 going into it. There is a separate cylinder, about 1.5" in diameter with a float valve. The bottom several inches contain CO2 gas, the rest of the chamber is water (above the gas). As CO2 is used up, the float valve falls and triggers the input of more gas. The only thing that can be controlled is the L/day of effluent. It is an ingenious design and very easy to use, (but if 38 dKh is too high and detrimental, then maybe this reactor isn't the best?) But, I suspect the type of media may make a difference. If it is true that some, like Reborn, dissolve more quickly than the Deltec calcite, it may be that the effluent volume/day can be greatly reduced, thereby introducing less CO2 into the tank. As mentioned, I plan to try the Reborn soon.

It is unused co2 that escapes the reactor that is the problem, not the pH of the effluent. This is nearly impossible to measure and hardest for most people to understand. People look at media and all of that, but it does not matter. If the airborne co2 is in the 400s or 500s, then your reactor is letting unused co2 in the tank if it is the reason that your tank pH is low. If this is true, then it is the design. In the most simple terms the easier the reactor, the worse the design for efficiency... if you want a reactor that is efficient, then you have to tune it yourself to balance co2 with contact time (flow and time). That area in the Deltec with the co2 bubble has to be as large as possible to accommodate a very high load, which means that it is likely too large under normal loads and more gas exchange is happening than needed (and escaping)... easy to work, but not efficient. IMO, for a reactor like the deltec to be efficient, the surface area of the co2 bubble would need to be shrunk or enlarged to balance contact with time and flow for the desired output. Cannot have unlimited access to co2 - same with having too much co2 in the air, the greedy water will gobble up too much. This is similar to having a carburetor with the maximum fuel (or air) and you only regulated the other - it would run, but would likely run be nowhere near efficient since you need to regulate access to both in a good ratio.

38 dKh is not a problem in it's self - plenty reasonable. I could tune my Korallin to be at 38 but not have excess co2 go into the tank. I could also tune it to where all kinds of co2 left the reactor with a dKh of 38 with too much co2 and too much flow... like letting a carbonated water into the tank (this is not exactly true, but you get it).