Evaporation - what is a reasonable amount

[FishyFishy!]

I'd say that is normal. It really depends on the open surface area of open water. I have a 30 gallon 24 X 24 with a completely open top and I loose that much easily in a day.

If you had glass tops, they help with evaporation, but then oxygen exchange gets lowered as well.

[Blom]

Yup mucho mucho water. Im a 5G pail every 4 - 5 days, 28G with open top.

[mike31154]

My 77 with open top evaps about a gallon/day, so your numbers are comparable. How's the humidity in your house? If dry, which is typical in many colder regions of our fine land in the winter, that will contribute to a bit more evap from your tank. Also if you have any fans blowing for lighting, that will contribute to additional evaporation. I doubt that adding a filter will change the evap rate that much.

[RyanJ]

On a hot day in the summer on my 125 I have font through 3G in one day bud! I have a 125 with a open top and a 60g sump open top! I just added a 30g frag tank with a 400w de mh with a open top aswell and I'm going through a 6L a day..

[Delphinus]

It is soooo dry here in Calgary, evaporation is going to be pretty quick. I lose nearly a gallon a day out of my FRESHWATER tank I keep upstairs. It drives me nuts that I have to do the bucket brigade on this tank whereas in my basement where I keep my salt tanks the topoff is all nicely automated. Family won't let me get rid of the freshies though, they consider that "their" tank (even though I seem to be the one carrying the buckets.. I'm not sure what's up with that, but I guess I digress.)

Anyhow I would agree that your evaporation losses sound pretty normal to me.