Evaporation/top off figures
- Thread starter jordannkids
- Start date
- Tagged users None
zachxlutz
120 Gallons of FUN
Mark the water line on your tank (assuming no sump). Let evap for 24 hours. Mark new line. Measure distance between two lines. Use a tank volume calculator and plug in width, depth and the height will be distance the water went down. Should give you a pretty exact value of evaporation.
Coastie Reefer
Valuable Member
Well... that's really kind of tough to pinpoint. The evaporation will vary day to day due to relative humidity, whether you run a ceiling fan, keep the room door open or closed, etc. The best way is probably to get a visual marker in the tank and fill to that point every morning or evening with a graduated container. Do that for a few days and take the avg...
Coastie Reefer
Valuable Member
Do you have an ATO? If so, get a graduated container and check it everyday over a couple days. They sell paint containers at WalMart on the cheap that have marks for mixing paint.
zachxlutz
120 Gallons of FUN
Same answer as I wrote above, just use the dimensions of the compartment your return pump is in as that is where your evaporation is happening.
Coastie Reefer
Valuable Member
What exactly are you trying to determine, and why?
ludnix
Valuable Member
I get the salinity of my aquarium correct and water line where I want it on the sump. I then use a pen to mark where the water line is on the outside of the glass. The next day I add enough R/O to get the water back up to the line and my salinity will stay correct. Adding an Auto Top Off and put the float switch where the line is drawn and you will maintain the salinity and water line automatically.
ludnix
Valuable Member
I would do the pen trick I said, then use a measuring cup or other measuring device to see how much you need to add in a day. If it's two cups of R/O water then google "2 cups to ml" and then set the doser to add that many ml each day. This is not a good long term solution though, as others have said your evaporation will vary from day to day and you can only get a ball park figure. If you want to use a dosing pump you should get a float switch and have the float switch turn the dosing pump on and off. Otherwise you risk your evaporation per day lowering and overdosing the tank with top off water, potentially leading to a flood.
Coastie Reefer
Valuable Member
Gotcha... I just let my ATO figure it out for me 
govolsguy31
Active Member
Like posted above, it's going to vary day by day. I have a 90G with a 20G sump and I lose 5G every 2-4 days. You're going to need a legit ATO or do it manually. Using a dosing pump is asking for a flood in my opinion.
ludnix
Valuable Member
http://autotopoff.com/Double/index.html These are an example of a dual float switch setup, you can plug your doser into these and have the water line perfectly managed all day.
