Dosing Oxygen to offset pH drop from Ca Reactor?

Tobe71 · Apr 1, 2019

Just did my first maintenance on my Vertex RX-C 6D Calcium Reactor. The media chamber was only about half empty but my Kameor Peristaltic Dosing pump was having difficulty pulling water through the reactor for some reason (and the pump is brand new as I just got a replacement after the screen on my first one went dead after about 2 months), so I opted to tear it down and clean it out and refill the media.

I guess you could chalk this up to, “if it ain’t broke don’t fix it” but while doing the maintenance which included calibrating the pH probe, I decided to calibrate the pH probe of my Pinpoint monitor that I use for the tank. To my surprise the probe in the reactor was still perfectly calibrated but the one for my system was WAY off. I had been under the impression my tank was running between 8.1 and 7.85 for months, but after the calibration the reality hit and my tank is running at 7.75-7.55?!? But if everything looks healthy and is growing well and it’s been like this presumably for months, do I change anything at all?

Everything has been doing great and the only thing I’ve noticed different is the slowing of my chaeto growth in my fuge.

I’m gonna play around with the pH within the reactor and the flow rate to hopefully reduce the impact on my pH but a thought came to mind. And please forgive me as I’m sure this is WAY oversimplified.

If the pH is being driven down by the amount of CO2 being introduced to the system could you counteract this effect by dosing Oxygen, say as a supplement to the air normally drawn into your Skimmer or even just through a bubble wand or wooden air stone in your sump to increase absorption?
Would dosing straight O2 or even oxygen enriched air cause any issues in nit thinking of? And as long as we are talking about Oxygen, what about using Ozone? (My least favorite option)

Any and all input is greatly appreaciated!

PS I’m considering approaching it the traditional way with Kalwasser in my ATO but for some reason that just seems like such an anomalous thing to me. How can you know exactly what concentration you are adding as the ATO reservoir would be constantly changing as water is used and then water is added and kalwasser is depleted and then replenished. And that doesn’t even account for the variations in your evaporation rates that would impact your kalkwasser “dosing”.

Hey Randy, what are your thoughts?

Dan_P · Apr 1, 2019

Tobe71 said:
Just did my first maintenance on my Vertex RX-C 6D Calcium Reactor. The media chamber was only about half empty but my Kameor Peristaltic Dosing pump was having difficulty pulling water through the reactor for some reason (and the pump is brand new as I just got a replacement after the screen on my first one went dead after about 2 months), so I opted to tear it down and clean it out and refill the media.

I guess you could chalk this up to, “if it ain’t broke don’t fix it” but while doing the maintenance which included calibrating the pH probe, I decided to calibrate the pH probe of my Pinpoint monitor that I use for the tank. To my surprise the probe in the reactor was still perfectly calibrated but the one for my system was WAY off. I had been under the impression my tank was running between 8.1 and 7.85 for months, but after the calibration the reality hit and my tank is running at 7.75-7.55?!? But if everything looks healthy and is growing well and it’s been like this presumably for months, do I change anything at all?

Everything has been doing great and the only thing I’ve noticed different is the slowing of my chaeto growth in my fuge.

I’m gonna play around with the pH within the reactor and the flow rate to hopefully reduce the impact on my pH but a thought came to mind. And please forgive me as I’m sure this is WAY oversimplified.

If the pH is being driven down by the amount of CO2 being introduced to the system could you counteract this effect by dosing Oxygen, say as a supplement to the air normally drawn into your Skimmer or even just through a bubble wand or wooden air stone in your sump to increase absorption?
Would dosing straight O2 or even oxygen enriched air cause any issues in nit thinking of? And as long as we are talking about Oxygen, what about using Ozone? (My least favorite option)

Any and all input is greatly appreaciated!

PS I’m considering approaching it the traditional way with Kalwasser in my ATO but for some reason that just seems like such an anomalous thing to me. How can you know exactly what concentration you are adding as the ATO reservoir would be constantly changing as water is used and then water is added and kalwasser is depleted and then replenished. And that doesn’t even account for the variations in your evaporation rates that would impact your kalkwasser “dosing”.

Hey Randy, what are your thoughts?

It is tempting to think CO2 and O2 are “opposites” because one “kills” and one “invigorates”. The response of pH to CO2 in water is to decrease because carbonic acid is formed when CO2 dissolves. Oxygen plays no direct role altering the pH of water because it does not react with water to form a base or an acid.

I will leave it to the calcium reactor experts to guide you on resolving your pH issue.

Bpb · Apr 1, 2019

Tobe71 said:
Just did my first maintenance on my Vertex RX-C 6D Calcium Reactor. The media chamber was only about half empty but my Kameor Peristaltic Dosing pump was having difficulty pulling water through the reactor for some reason (and the pump is brand new as I just got a replacement after the screen on my first one went dead after about 2 months), so I opted to tear it down and clean it out and refill the media.

I guess you could chalk this up to, “if it ain’t broke don’t fix it” but while doing the maintenance which included calibrating the pH probe, I decided to calibrate the pH probe of my Pinpoint monitor that I use for the tank. To my surprise the probe in the reactor was still perfectly calibrated but the one for my system was WAY off. I had been under the impression my tank was running between 8.1 and 7.85 for months, but after the calibration the reality hit and my tank is running at 7.75-7.55?!? But if everything looks healthy and is growing well and it’s been like this presumably for months, do I change anything at all?

Everything has been doing great and the only thing I’ve noticed different is the slowing of my chaeto growth in my fuge.

I’m gonna play around with the pH within the reactor and the flow rate to hopefully reduce the impact on my pH but a thought came to mind. And please forgive me as I’m sure this is WAY oversimplified.

If the pH is being driven down by the amount of CO2 being introduced to the system could you counteract this effect by dosing Oxygen, say as a supplement to the air normally drawn into your Skimmer or even just through a bubble wand or wooden air stone in your sump to increase absorption?
Would dosing straight O2 or even oxygen enriched air cause any issues in nit thinking of? And as long as we are talking about Oxygen, what about using Ozone? (My least favorite option)

Any and all input is greatly appreaciated!

PS I’m considering approaching it the traditional way with Kalwasser in my ATO but for some reason that just seems like such an anomalous thing to me. How can you know exactly what concentration you are adding as the ATO reservoir would be constantly changing as water is used and then water is added and kalwasser is depleted and then replenished. And that doesn’t even account for the variations in your evaporation rates that would impact your kalkwasser “dosing”.

Hey Randy, what are your thoughts?

Dan_P is correct. While they’re related through aerobic respiration , O2 and CO2 are unrelated when it comes to PH. High CO2 will cause low PH even if O2 is elevated to toxic levels

Dkeller_nc · Apr 1, 2019

Well, one thing to note is that it's not possible to elevate the oxygen concentration to toxic levels in seawater, as not enough will dissolve. And in a reef environment (at least the reef slope and crest), the waters are at nearly 100% oxygen saturation for that particular temperature.

From the standpoint of pH control, however, Dan and BpH are correct; it makes no difference whether one used oxygen, nitrogen, or any other gas to strip CO2 out of the water. Obviously, one would not choose to use nitrogen, argon, helium or any other non-breathable gas in one's skimmer, since in addition to stripping the CO2 you'd also depress the oxygen levels in the tank. It'd also be really expensive.

You've several choices with respect to the pH in your system. You could add a gas-stripping column to the output of your calcium reactor - it would essentially be a container with an air stone/air pump in it. Another choice would be to add a CO2 stripper on the air intake of your skimmer. Finally, you could dial down the calcium reactor output somewhat and dose sodium hydroxide solution as part of your alkalinity management (kalkwasser's another choice, but because it's so dilute, it may not have much pH boosting effect).

Of all of these options, perhaps the simplest conceptually and with the least risk is to add a CO2 stripper/scrubber to your skimmer's air intake. That will remove a great deal of CO2 from the tank water in the skimmer, although if the room that the tank's in isn't well ventilated, that CO2 may just re-dissolve into the tank water.

LobsterOfJustice · Apr 1, 2019

Before you go crazy, I would double check your “new” pH reading. I don’t think a reading of 7.55 - 7.75 for an otherwise healthy reef tank is correct.

Bpb · Apr 1, 2019

Dkeller_nc said:
Well, one thing to note is that it's not possible to elevate the oxygen concentration to toxic levels in seawater, as not enough will dissolve. And in a reef environment (at least the reef slope and crest), the waters are at nearly 100% oxygen saturation for that particular temperature.

From the standpoint of pH control, however, Dan and BpH are correct; it makes no difference whether one used oxygen, nitrogen, or any other gas to strip CO2 out of the water. Obviously, one would not choose to use nitrogen, argon, helium or any other non-breathable gas in one's skimmer, since in addition to stripping the CO2 you'd also depress the oxygen levels in the tank. It'd also be really expensive.

You've several choices with respect to the pH in your system. You could add a gas-stripping column to the output of your calcium reactor - it would essentially be a container with an air stone/air pump in it. Another choice would be to add a CO2 stripper on the air intake of your skimmer. Finally, you could dial down the calcium reactor output somewhat and dose sodium hydroxide solution as part of your alkalinity management (kalkwasser's another choice, but because it's so dilute, it may not have much pH boosting effect).

Of all of these options, perhaps the simplest conceptually and with the least risk is to add a CO2 stripper/scrubber to your skimmer's air intake. That will remove a great deal of CO2 from the tank water in the skimmer, although if the room that the tank's in isn't well ventilated, that CO2 may just re-dissolve into the tank water.

Lol I realized that after typing that it’ll just offgas before being toxic. Just making a point

Tobe71 · Apr 2, 2019

Dan_P said:
It is tempting to think CO2 and O2 are “opposites” because one “kills” and one “invigorates”. The response of pH to CO2 in water is to decrease because carbonic acid is formed when CO2 dissolves. Oxygen plays no direct role altering the pH of water because it does not react with water to form a base or an acid.

I will leave it to the calcium reactor experts to guide you on resolving your pH issue.

Thanks for the input.

I assumed Oxygen may help as it is often recommended to have air pulled from outside the home to feed your Skimmer with presumably more oxygen rich air...

Water Dog · Apr 2, 2019

Get yourself a kalk stirrer, like the Avast K1 and use a dedicated peristaltic dosing pump, like the Spectrapure standalone 50ml/min or the Avast 25ml/min pumps and put it on a timer or Apex outlet so you can precisely control the kalkwasser dosing in order to help boost pH.

Dkeller_nc · Apr 2, 2019

Tobe71 said:
Thanks for the input.

I assumed Oxygen may help as it is often recommended to have air pulled from outside the home to feed your Skimmer with presumably more oxygen rich air...

That's not the reason for outside air. In a home that's well insulated and has a lot of people/pets in it, the CO2 concentration can be far higher than the outside air. So if the skimmer's pulling the indoor air into the tank water, the equilibrium dissolved CO2 concentration will be a good deal higher and the pH a good deal lower than if the skimmer is fed outdoor air. Even more of a CO2-stripping effect can be gained by using a lime CO2 scrubber on the incoming air so that it essentially has zero CO2.

Tobe71 · Apr 3, 2019

Dkeller_nc said:
That's not the reason for outside air. In a home that's well insulated and has a lot of people/pets in it, the CO2 concentration can be far higher than the outside air. So if the skimmer's pulling the indoor air into the tank water, the equilibrium dissolved CO2 concentration will be a good deal higher and the pH a good deal lower than if the skimmer is fed outdoor air. Even more of a CO2-stripping effect can be gained by using a lime CO2 scrubber on the incoming air so that it essentially has zero CO2.

Got it. That's what I get for assuming. For a minute I thought I had discovered a new solution that had been overlooked! Ha!

Tobe71 · Apr 3, 2019

LobsterOfJustice said:
Before you go crazy, I would double check your “new” pH reading. I don’t think a reading of 7.55 - 7.75 for an otherwise healthy reef tank is correct.

I'll be checking it against a test kit and a new Hanna Blue Tooth pH probe tonight...

Randy Holmes-Farley · Apr 6, 2019

Dkeller_nc said:
Well, one thing to note is that it's not possible to elevate the oxygen concentration to toxic levels in seawater, as not enough will dissolve. And in a reef environment (at least the reef slope and crest), the waters are at nearly 100% oxygen saturation for that particular temperature.
.

I don't agree. Reefs are at 100% saturation relative to air that is only 21% O2. Not to air that is 100% O2.
You are confident that raising the O2 level in seawater by a factor of 5 is not toxic? I think that is probably toxic.

Dkeller_nc · Apr 6, 2019

Randy Holmes-Farley said:
I don't agree. Reefs are at 100% saturation relative to air that is only 21% O2. Not to air that is 100% O2.
You are confident that raising the O2 level in seawater by a factor of 5 is not toxic? I think that is probably toxic.

Yes, I'm confident, though not from actually doing controlled experiments, it's just anecdotal. I take home bags of fish and other critters from a LFS on a regular basis that have a 100% oxygen atmosphere in the bag, and I've not see any mortality to date. Granted, however, that's not quite the same as bubbling oxygen continuously through seawater, where super-saturation might be a possibility.

Randy Holmes-Farley · Apr 6, 2019

Dkeller_nc said:
Yes, I'm confident, though not from actually doing controlled experiments, it's just anecdotal. I take home bags of fish and other critters from a LFS on a regular basis that have a 100% oxygen atmosphere in the bag, and I've not see any mortality to date. Granted, however, that's not quite the same as bubbling oxygen continuously through seawater, where super-saturation might be a possibility.

OK, I don't have definitive data, just literature reports of fish being stressed by high O2.

rkpetersen · Apr 6, 2019

Tobe71 said:
Thanks for the input.

I assumed Oxygen may help as it is often recommended to have air pulled from outside the home to feed your Skimmer with presumably more oxygen rich air...

Hi. Oxygen isn't involved in that.
The reason that pulling air from the outside is recommended is because outside air is typically around 400 ppm CO2, while inside air can have much higher levels, even up over 1000 in some cases.
Basements can be particularly bad as far as elevated CO2 levels. And any house that's generally tightly sealed with lots of occupants (people and dogs.)
So using outside air might result in much less CO2 being mixed into your water by the skimmer than using inside air, and therefore you'll see an increase in pH.
Using a CO2 scrubber is even better, and will give you a very reliable increase in pH of perhaps 0.2 units, depending on details.
But the problem is that the media for the scrubber isn't that cheap, can't be renewed, and may have to be replaced pretty often.