:surprise:! Are you sure? That's quite a big swing.

Cheers:smile:,

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How does that work? If the fans are cooling the water then there should be less evaporation, no?

I wouldn't even know how to scientifically explain how this works, but I know fans contribute to evap. Even if I turn my bedroom fan on, I get double the evaporation. plus, I've ran fans across my water and I seen horrible evaporation so I had to stop using it.

Yeah ... that is generally what i have been reading from the refractometer ... though it doesn't seem right at all.

Given that 5 gallons shouldn't raise the SG that high.

I think i will have to recalibrate it

Ok, I think this is how this happens...
Water evaporates cooling the tank, but without air movement the moist air remains above the tank.
Air can hold only so much water so when it becomes saturated evaporation slows down but then the cooling also slows.
With a fan moving the saturated air away it allows for more water to evaporate keeping the tank cooler but also increasing the amount of water that is allowed into the air.
Make sense?

Dan

I agree. Makes sense to me. The key is the movement of the humid air out of the way, IMO.

Cheers:smile:,

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I guess that makes sense Dan, thanks.

My tank evaporates a couple of gallons a day as well, about 8-9 gallons per week. So I adjusted the baffels in my sump so that I don't have to fill it up as often.

I have 200g of volume and use 14 gallons a week of top off water rigged through a 7 gallon camping water jug, (nice volume & fits behind the tank), hooked to a Kalkreactor and on to a float valve in the sump... no salinity issues, and I control the evaporation rate by turning my fans up or down through a dimmer switch... I use a chiller as well but control over the evaporation rate for me is as much for Calcium maintenance as it is for cooling...

Well after recalibrating my refractometer, i did the tests again in the morning and then at night (when the water was gone)

In the morning it was reading a perfect 1.025 ... in the evening it was at the most 1.0258 ... jsut under 1.026.

So i don't think that is a BAD swing .... i could be wrong and i am sure that i will be told if i am wrong :)

Thanks all

No...I would say that is not a bad swing at all (0.0008). Like I said earlier, IME I got swings of 0.001-0.002 with 10% evap.
Maybe you meant to say in your previous post the other day that your swings were 0.001-0.0015 and not 0.01-0.015? Just a thought.

Cheers:smile:,