Unusual Evaporation Rate?

[USMCGrunt]

Ive got a dual loop system (120x3 covering x3 GPUS and 120x2 covering CPU) and my GPU loop either has an incredibly slow leak or for some reason experiences a really high evaporation rate...im assuming the water is...cant remember the term for it...but evaporating through the tubing. My CPU loop has never needed refilling but the GPU loop has had to be refilled three times in the last six months and is on its way to getting topped off again. Its probably equal to about 10-15ml so its not a TON but its just strange that the CPU loop doesnt require the same maintenance. I use regular distilled water and clear Tygon tubing. There is no water whatsoever anywhere in the case, ive checked and rechecked all connections for leaks but its all good.

I can see it happening faster with the GPU loop because it DOES handle a lot more heat than the CPU loop...it just seems a bit lopsided.

 

[Tsumi]

I notice that when I don't game much, I rarely lose any water, but when I start doing more intensive tasks for long periods of time, I lose water quicker.

 

[JLangevin]

Im pretty sure that you arent losing it, but in fact just replacing air that is still trapped in portions of the loop.

Plenty of air can actually get trapped and not make any sounds or effect flow whatsoever but the changes in temerature literally help move the pockets and replace it with water.

If you dont refill it, does the level get to a certain point and then stop? When I flush my system or build a new one, I always do stress testing to assist with bleeding because the warmer temps seriously do help.