Does adding a fan increase evaporation without increasing CO2?

[Miami Reef]

It’s clear as day. I have extreme surface agitation to try increase evaporation and to “bring my PH up”. There is very very little ph swing day to night.

I am just now using kalkwasser and I topped my tank off and brought my ph to 8.2, and I watched it almost instantly (within that minute) see it come back down to 8.03.

I limited surface agitation and added some more kalk and noticed that ph is staying at 8.14 without dosing much kalk.

I would like to increase my evaporation because it will increase the rate I can dose kalkwasser.

Will blowing a fan evaporate without increasing the rate CO2 enters the tank? Or will it just blow CO2 air into the tank?

 

[EeyoreIsMySpiritAnimal]

Can you work out a way to pull outside air into the system? (I do realize you're in FLA and it's summer, lol). A fan shouldn't add any more CO2 than is what is already in the room air, but I doubt it will lower the CO2...

 

[EeyoreIsMySpiritAnimal]

Is your tank suffering at 8.03? That seems to be in range...

 

[Miami Reef]

Is your tank suffering at 8.03? That seems to be in range...

Tank is not suffering. I just want to increase it because I believe a ph of 8.3 is most optimal. It’s easier for corals to calcify and is generally good for a reef tank IMO.

 

[EeyoreIsMySpiritAnimal]

Tank is not suffering. I just want to increase it because I believe a ph of 8.3 is most optimal. It’s easier for corals to calcify and is generally good for a reef tank IMO.

Unless the fan is pulling in air from somewhere with a higher CO2 level than is already around the tank, I don't think it will add any to the system... If your main goal is evap, it's definitely worth a try.
Good luck

 

[Miami Reef]

Unless the fan is pulling in air from somewhere with a higher CO2 level than is already around the tank, I don't think it will add any to the system... If your main goal is evap, it's definitely worth a try.
Good luck

Ah, it probably is? Especially if my ph is artificially raised with kalk. Then the surrounding co2 will be higher which will make air want to equilibrate with the tank.

But the flip side is more aeration = more kalk dosed. Will more kalk be dosed relative to the co2 that enters the tank?

I don’t know. Maybe I need to experiment. First I will reduce aeration to see my highs and lows in my tank. Then I guess I can experiment.

 

[EeyoreIsMySpiritAnimal]

Ah, it probably is? Especially if my ph is artificially raised with kalk. Then the surrounding co2 will be higher which will make air want to equilibrate with the tank.

But the flip side is more aeration = more kalk dosed. Will more kalk be dosed relative to the co2 that enters the tank?

I don’t know. Maybe I need to experiment. First I will reduce aeration to see my highs and lows in my tank. Then I guess I can experiment.

But is air already entering your system via the skimmer? I doubt a fan will add a higher concentration of CO2 than that does... But I honestly don't know. You could set up a mini AWC to pull out some water if other options don't work.

 

[Garf]

It’s clear as day. I have extreme surface agitation to try increase evaporation and to “bring my PH up”. There is very very little ph swing day to night.

I am just now using kalkwasser and I topped my tank off and brought my ph to 8.2, and I watched it almost instantly (within that minute) see it come back down to 8.03.

I limited surface agitation and added some more kalk and noticed that ph is staying at 8.14 without dosing much kalk.

I would like to increase my evaporation because it will increase the rate I can dose kalkwasser.

Will blowing a fan evaporate without increasing the rate CO2 enters the tank? Or will it just blow CO2 air into the tank?

If you’ve got the sump enclosed you can try leaving the doors open. See if that helps. CO2 can sit on the surface of the sump, it’s known as CO2 pooling.
I assume you know that kalk increases Alkalinity, which at least to start will be the limiting factor of how much you can add.

 

[Sean Clark]

Everything is always moving towards equilibrium. Sounds like your location may have elevated co2.

 

[Randy Holmes-Farley]

It’s clear as day. I have extreme surface agitation to try increase evaporation and to “bring my PH up”. There is very very little ph swing day to night.

I am just now using kalkwasser and I topped my tank off and brought my ph to 8.2, and I watched it almost instantly (within that minute) see it come back down to 8.03.

I limited surface agitation and added some more kalk and noticed that ph is staying at 8.14 without dosing much kalk.

I would like to increase my evaporation because it will increase the rate I can dose kalkwasser.

Will blowing a fan evaporate without increasing the rate CO2 enters the tank? Or will it just blow CO2 air into the tank?

It’s a bit of a complicated question to answer, but blowing air over the water can help equilibrate the water to the air faster. If the air and water are already at equilibrium, it will not cause CO2 to go in or out.

 

[Miami Reef]

It’s a bit of a complicated question to answer, but blowing air over the water can help equilibrate the water to the air faster. If the air and water are already at equilibrium, it will not cause CO2 to go in or out.

I’m bumping this to ask another question,

Imagine this scenario: tank is getting vigorously aerated. Like, pretend it’s exactly in equilibrium and any changes in CO2 inside the tank are quickly back in equilibrium with the surrounding air.

In this scenario, will 100% of the ph boosting effects of hydroxide not have any effect whatsoever?

I want to aerate my tank heavily because it helps get nasties suspended and helps with oxygen, but if it will end up negating the ph boosting effects of hydroxide, then I’d rather limit aeration.

 

[Miami Reef]

And FYI, my ph ranges from 8.26 to 8.11. I just recently calibrated without any hydroxide dosing. I live in a larger house with doors constantly opening.

I’m just curious about the ph question above.

 

[Randy Holmes-Farley]

I’m bumping this to ask another question,

Imagine this scenario: tank is getting vigorously aerated. Like, pretend it’s exactly in equilibrium and any changes in CO2 inside the tank are quickly back in equilibrium with the surrounding air.

In this scenario, will 100% of the ph boosting effects of hydroxide not have any effect whatsoever?

I want to aerate my tank heavily because it helps get nasties suspended and helps with oxygen, but if it will end up negating the ph boosting effects of hydroxide, then I’d rather limit aeration.

The only effect in that scenario is from the alk increase, and would be the same with bicarbonate, carbonate, or hydroxide. If the theory was not convincing enough, I measured it myself for a 1.4 dKH boost with each of those in a stirred beaker in a chemical fume hood. They all matched at equilibrium.

 

[Sean Clark]

If you had that much gas exchange that your co2 was in equilibrium with the surrounding air and you still had a pH "problem" then I would think they your surround air would likely have elevated co2. Dosing Hydroxide won't do anything for the air.

 

[Randy Holmes-Farley]

I show that experiment here:

Chemistry And The Aquarium: The Relationship Between Alkalinity And pH ? Advanced Aquarist | Aquarist Magazine and Blog

 

[Randy Holmes-Farley]

From it:


er:

Supplement	Initial pH	24 hour pH	120 hour pH
none	8.10	8.11	8.21
0.5 meq/L HCO3-	8.06	8.15	8.33
0.5 meq/L CO3–	8.44	8.28	8.34
0.5 meq/L OH-	8.76	8.47	8.33
0.5 meq/L H+	6.91

 

[Randy Holmes-Farley]

Note how long it took!

 

[Miami Reef]

Note how long it took!

This is what I needed to hear! So I learned that equilibrium does not happen as quick as I thought it would. That means that I can enjoy the benefits of my hydroxide and have moderate aeration. Awesome.