Evaporation in Sump

[csr1]

Can anyone tell me how much on an average that they notice evaporates out of the sump and over what period of time?
I have a 30 gallon sump on a 200 gallon tank. I just purchased this tank about 3 weeks ago and have had it running for about 2 weeks. I haven't really been using the lights that much until just a few days ago when I got the timer put on the MH's. Now I notice that I am losing about 1/2 - 3/4 of an inch of water out of the sump from the time I go to work in the morning at 7:00 am and when I come home at 5:00 pm.
The person I bought the tank from has the ballasts for the lights (all four of them) inside the sump fastened to the left side. There is no fan blowing underneath the tank.
Can you tell me if this is a normal amount of evaporation for this kind of set up or should I be doing something differant.
I was wondering if I had an acrylic or or plastic cover made for the sump if that would help the evaporation a little or would it be better to rig up a small fan somehow underneath there to keep down the amount of evaporation I have going on? Any help is much appreciated. Thanks

 

[splash1914]

I maybe lose 5 gallons a week to week and half.....

 

[maryc137]

I lose about 1/2 gallon a day.

 

[sebae0]

my tank has a open top and my sump is partially open and i lose approx. 2-4 gals a day and thats from 7:00 to 5:00.

 

[csr1]

Thanks for the reply's everyone. I have never had a setup this big before and used a sump.
I didn't realize that I would lose this much in evaporation every day and was concerned that I should be doing something differant.
Thanks for all the information. This site is wonderful about responding and being kind enough not to treat some of us "less experienced" saltwater fanatics like complete lame brains for not knowing something like this.
Again thanks for the advice and I won't worry so much now.

 

[cadbury]

csr1, I'm having the same problem from my 180. I have an ecosystem and I'm losing about 1/2 gallon maybe more a day? I'm going to try to rig up a cover for it and see if that helps?

 

[slothy]

cad i lose 1 gallon a day on my 40...

 

[von_rahvin]

i lose around 3-6 gal a week in the 135 annd around 1 in the 65. but i chill my tank by evap. (i have fans blowing across my sumps)