Tank size and evaporation

[Jasper05]

Not sure where to post this... Or how to actually word this lol

My concern is evaporation and humidity. My total volume is only about 80 gallons, but my surface area would be of a much larger tank. I have a 40 breeder display, 20 l sump, and 30 cube refugium(24x24x12)

So my question...
In theory, would a 45 gallon (72×24×6) evaporate at the same rate as a standard 180 gallon (72×24×24)?

 

[theMeat]

Hmm
Ime the biggest factor is how much surface water movement you have, followed by temp and humidity of the room the tank is in.
Can easily double the amount of evap on my 220 by increasing surface water movement

 

[Auquanut]

In theory, would a 45 gallon (72×24×6) evaporate at the same rate as a standard 180 gallon (72×24×24)?

I would say that all thing being equal: Temp, humidity, water movement, etc..., yes. But that's just a WAG.

 

[Auquanut]

Just had a thought. With the 180 holding so much more water, and the O2 constantly being introduced and gassing off of both tanks, maybe the 180 might evaporate a bit more as the higher amount of gas exchange carries more water vapor with it. This would be a SWAG. (scientific Wild A** Guess)

 

[Cell]

More direct air contact = more evaporation

 

[Jasper05]

Just had a thought. With the 180 holding so much more water, and the O2 constantly being introduced and gassing off of both tanks, maybe the 180 might evaporate a bit more as the higher amount of gas exchange carries more water vapor with it. This would be a SWAG. (scientific Wild A** Guess)

I can roll with that swag

 

[Reef.]

I would just measure the amount of rodi water in the reservoir, see how much it deduces in 24hours.

 

[Andreas' Reef]

In my experience I lose 1 cup of water per day with a lid.

 

[Randy Holmes-Farley]

Just had a thought. With the 180 holding so much more water, and the O2 constantly being introduced and gassing off of both tanks, maybe the 180 might evaporate a bit more as the higher amount of gas exchange carries more water vapor with it. This would be a SWAG. (scientific Wild A** Guess)

No, it doesn't work that way. The exchange of H2O both ways and any other gases both ways are largely independent.

If the water is not coated with organics, then flow won't matter appreciably either. Flow will prevent a protective barrier of organics from forming, which if it did, can drastically slow evaporation and gas exchange.

Air flow will matter a lot, to bring in air unsaturated with water to replace the air that has become saturated (or near to it).

Air temp, water temp, and air humidity all also matter a lot.

Surface area, obviously, is a big factor.

 

[Jasper05]

No, it doesn't work that way. The exchange of H2O both ways and any other gases both ways are largely independent.

If the water is not coated with organics, then flow won't matter appreciably either. Flow will prevent a protective barrier of organics from forming, which if it did, can drastically slow evaporation and gas exchange.

Air flow will matter a lot, to bring in air unsaturated with water to replace the air that has become saturated (or near to it).

Air temp, water temp, and air humidity all also matter a lot.

Surface area, obviously, is a big factor.

Thanks for the detail. So it seems like, in my example, the humidity mitigation plan would be similar in both the 45 gallon and 180 gallon because the they have the same surface area, therefore, similar evaporation rates

 

[ShepherdReefer]

Great topic and response. Love to learn.

 

[VR28man]

Not sure where to post this... Or how to actually word this lol

My concern is evaporation and humidity. My total volume is only about 80 gallons, but my surface area would be of a much larger tank. I have a 40 breeder display, 20 l sump, and 30 cube refugium(24x24x12)

So my question...
In theory, would a 45 gallon (72×24×6) evaporate at the same rate as a standard 180 gallon (72×24×24)?

I don't know the physics, but from my experience (and very anecdotal online surveys) you lose about 1% of your water volume per day if you keep
an open tank.

 

[Soren]

I don't know the physics, but from my experience (and very anecdotal online surveys) you lose about 1% of your water volume per day if you keep
an open tank.

Yes, but evaporation surely depends on surface area? I think for the anecdotal 1% to be accurate, you would need to be comparing tanks of similar proportions for there to be a correlation.

If you consider extremes, a tank that is 48"LX48"WX6"H (like a large frag tank, maybe?) versus a tank that is a 24" cube or a 48"L X12"WX24"H (more typical reef proportions), all have the same volume but not the same surface area. I would expect the anecdotal 1% to be more accurate for the latter two hypothetical reef tanks and much lower than the actual evaporation on the hypothetical frag tank.

This, of course, assumes all other factors are the same (temperature, heat loss and gain, surface flow, volume flow, air flow, etc.).

 

[saltyhog]

I don't know it would be the same as the 180 (but I think it probably would be) but it would be a ton more than a tank with the same volume but a more normal foot print.

 

[Dr. Jim]

If the surface area of each is the same (72 x 24) then the evaporation rate would be the same, all other things being equal.