Do mesh safety covers stop evaporation?

Esand323

Well-known member
Aug 6, 2018
102
Indianapolis
Hi all,

Another evaporation question!

I have a mesh safety cover (Looploc). I closed my pool a bit earlier this year. The weather has been pretty warm. Mostly in the 70s with a few days in the 80s, but I still went ahead and closed the pool. I check the pool chemicals about once a week and balance. I use a submersible pump to circulate the water.

Typically we have to drain some water out of it a few times throughout the Winter. So it seems as though evaporation isn't really much of a factor. However, this year, after having it closed for about two weeks, it seems like there is some evaporation (or possibly a leak!). It seems like it should be possible for evaporation to occur with a mesh safety cover, but some of my research seems to say it greatly reduces it.

From what I've observed, we lose about 1/8" of water a day. I've only been observing it for the past 36 hours, so not a ton of data yet. But the nights have been in the 50s and days in the 70s (for comparison, last year we had 50 degree days at this time). The water temperature is in the low 70s. It appears that we lose most of the water at night. For instance, yesterday during the day I checked the levels a few times and didn't really notice any change in the water level. But when I checked at night, and then again in the morning, there was a larger change. So this points to evaporation to me.

Also, last night I went ahead and took the cover off a bit more and noticed that there was tons of water vapor/mist coming from the pool. I'm assuming this is evaporation? What's odd is that the RH outside was in the 90's, and there was plenty of condensation on the lawn, patio furniture, grill, etc. So it seems like evaporation really wouldn't have been an issue. I took a video of what I was seeing here:
.


So is it possible to still have evaporation with a mesh safety cover? It seems logical to me that the vapors would have no problem getting through the mesh material, but I can't seem to find a conclusive answer.

Thanks!


I forgot to add, I'm currently doing a bucket test right now under the mesh cover. It's only been about 12 hours, and early indication seems to show that it did lose a small amount of water. But too small right now to know definitively. Also, the weather hasn't been very cooperative.
 
Last edited:

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
44,337
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Evaporation will occur with a mesh cover. The low air temperature is directly on the higher water temperature. That is what causes the evaporation. With a solid cover, the air temperature directly on the water surface will approximate the water temperature. Thus little evaporation occurs.