See now I would think the other way on that. The smaller the tank the less evap needs to happen to change the salinity. My salinity could jump from .026 to .03 in the matter of a couple hours in this JBJ cube.

even my 97 has started losing a ton so my temporary topoff (5g bucket) is not even lasting me 2 days. I did have fans kick on WITH the chiller but have since unplugged the fans and told the chiller to just pickup the slack. This has reduced my evaporation some. I also lowered a powerhead ever so slightly as it was really churning the surface.

I'm manually topping off my tank downstairs with 5g everyday. I can't wait to have that on an auto topoff!

Surface area and temperature are the big factors for evaporation. My 65 gal with a 20 gal sump goes through about a gallon a day.

I'll check the salinity when I get home as I'm sure the water level will have dropped off. I did test it yesterday before topping off and was at 1.027 and hadn't been topped off since Friday as I was away for the weekend. I keep it around 1.025. I'm doing a water change tonight, hadn't been monitoring it as the tank has been stabilizing over the last bit and am seeing improvements. Will start to monitor and see what the actual difference is....

5 gallons every 3 days.

I turned my MP 40 down a bit last night but only because I added a couple of new clowns and a maxi mini, just letting them settle a bit. I had it turned up about 75% for the last month for both surface movement and to clean up the sand.

I really only noticed the increase in the evaporation with the addition of the fuge, cooler temps, and the furnace being on. Over the summer, I topped up every couple of days, wasn't nearly so much. The tank temp is 79-80.

Sounds like this is normal. Phew!

I lose 5 gal every 4 days on mine, RSM 250 with open top. It's gotten a bit faster since the cold. You should just get an ato...they're the best.

I think I lose about 5 gallons every 4 days as well on a 90 open top with hood and 2x 250W MH. My ATO uses a 5 gallon old salt bucket.