How much expected water loss in the res?

On average how much water is loss in evaporation do you have from your tanks in an op? I'm testing my DIY tank so wanted to have a base of comparison.
thanks
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my girls drink about 1 gal per 2x4 tray with a 12 gal rez 36 plants in veg and 15 in flower

*** per day ***

im filling my 27 gal res about 5 gallons every night. 1 res for 2 4x4 tables

18gal. Res 4x plants can drink over a gal. a day

This of course guys without the plants? I'm looking for rates of water evaporation from my res, not how much the little bitches drink =)

flamdrags420 said:

This of course guys without the plants? I'm looking for rates of water evaporation from my res, not how much the little bitches drink =)

Click to expand...

Depends on heat, humidity, air movement over reservoir if there is no cover...lots of variables.

But if you want to find out the rate of evaporation where "your" gonna grow then just measure out a gallon of water into a small bucket or bowl, put it in your grow area and mark it every few days at the different levels as it evaporates.

Let me expand on this. I have made my DIY tanks. I'm testing them. I lost about a quarter inch of water in 24 hours. About 1 L. I'm trying to find out if this would be evaporation or a leak in my tank. I've not found any evidence for a leak. I am trying to find out if this is a normal amount of evaporation.