evaporation from a 72 gal tank

[skydvr]

I know evaporation rates will vary depending on differential temp (tank to room), humidity, surface area, ect...
But i'm designing a sump with an area for makeup water and wanted to make sure I could go more than a few days without having to refill the tank.

So what do you see for evaporation a week or month?

 

[zoomfish1]

My 75g evaporates about a gallon a day under 500w of halides. Under PC's you would have about half that. I also have fans in the hood and one on the sump, so that makes it evaporate a little quicker.

 

[bbehring]

plan for auto top off or your be filling your tank every 10 minutes LOL! My 55 has a lot of evap. Running 250 MH w/ T5s, open tank top and open sump. Probably at 1 to 2 quats per day.

 

[sjj80]

For me it would be hard to estimate evap because I live in coastal georgia and if you or someone else lives further up north or inland than evap rates will be different from mine.

However, For my 90 gal w/ 20 gal sump I'm planning on using a 10 gal tank/reservoir with a reef fanatic auto top-off to handle my evap. I would definitely get the largest reservoir you can in order to be prepared for unexpected heat waves and for vacations-another good reason for auto-top off!
HTH

 

[Spuds725]

Humidity and whether you run a top makes a big difference also... I ran a 72 gallon (topless) with 15 gallon sump and evaporated 1.25 gallons per day... currently losing about 2.5 gallons per day on my 135 gallon topless tank with 50 gallon sump/fuge combo-- this tank is topless also...

both tanks were under PC lights--

If I were you and leaving town I would have a competent person check on the tank at least every other day and top off... as well as feed and check the tank for problems--

You can figure your change in salinity from evaporation with this calculator-- http://www.saltyzoo.com/SaltyCalcs/EvapSalinityCalc.php?sysGal=40&sal=35&evapGal=1.5

 

[PatMayo]

I have a 90 gallon with a 30 gallon sump. I guesstimate total water volume is 100 gallons. No top on the tank or sump. I have 2 ea. 150 watt mh lights. I evap about 1.2 gallons per day.

Regards,

Pat

 

[skydvr]

Thanks a lot everyone.

Looks like i'll be going with my first design, which gives me 8.5 gallons of make-up water.
My other design gave me 5.7, but allowed an extra gallon in the return area and an extra 1.75 for overflow incase of system shutdown.
Initial calculations show I shouldn't cause a flood, but I haven't really figured out overflow design yet.
I figured the tank has about 3.5 gallons per inch, so tank level can drop 2.25 inches into the sump and leave 1/4" to the top of the sump.