Water evaporation from a mesh covered pool in the winter?

[Annorax]

Hi all,

I have an in-ground, vinyl lined, DE filtered pool and live in MA. When closed, the pool has a green mesh cover that attaches via some pop-up studs in the ground.

About a month ago in mid-April, I opened up one of the ends to take a peak in as when closing, one of the returns had me a little worried as the face plate had a crack in it. Fortunately, the black rubber stopper was still firmly in place - though there was some dirt under it - but I think this came from above.

However, being paranoid, I kept watching it over the past month or so and I've been noticing the water level drop ever so slightly over time. It's been hard to gauge a rate but it seems to be maybe 1 inch a week, give or take. However, due to rain and the varying rate of it dropping, over the past month it has only lost roughly less than 2 inches. The pool is still fully covered though the cover has a couple of small holes in it due to age. I'm really hoping it's not a random leak or from the cracked return jet face plate and just evaporation. The rate of dropping has been hard to measure and doesn't seem consistent.

My overall question is this - how much water evaporation is normal for a mesh covered pool? It's starting to get warmer here - lows overnight are in the 50s and highs during the day are 70s to 80s, so there is a big temperature range. There is water sitting over the cover in the middle of the pool, I'm assuming that is seepage through it, which I read can cause evaporation too, as more water evaporates, more seeps up. I also read that these mesh covers are quite porous so evaporation can happen.

 

[mknauss]

Does the water stop dropping at the area of the cracked item?

I would say you have evaporation.

I also would think you should have opened this pool a while ago. You want to open the pool prior to the water reaching 60F.

Take care.

 

[Annorax]

Thank you for the reply. It hasn't gotten as far down to the return jet yet. It's still fairly high, not only above the skimmer basket but above the skimmer hole in the pool (though just barely at this point). But unfortunately I won't know if it's the cracked face plate or not until the water gets that low. I'm cautiously hopeful that it is evaporation, but I'm not sure what is considered "normal" evaporation for a mesh covered pool.

I agree, I was originally planning on opening the pool 2 weeks ago, but there was a mix up with my pool guys on my end and they are coming out this week instead.

 

[Pool_Medic]

A pool with a safety cover and unopened shouldn’t lose any water, in fact most fill up to over the skimmer. I suspect a leak.

 

[mknauss]

Is this a safety cover or a mesh cover?

 

[Annorax]

It's a green cover, I'm pretty sure it's mesh though not 100% as it came with the house. It looks identical to this one (though obviously a different shape and size as this it not my pool, just a Google image search ):

pool mesh cover - Google Search

 

[mknauss]

Ahh - I agree with Medic -- I would be prepared to start evaluating for a leak.

 

[Annorax]

I'm sorry for my confusion - what is the difference between a safety cover and a mesh cover?

I thought mine was mesh and therefore was porous and allowed for things like rain water to seep through it? I was getting a little hopeful when I read things like if there is water in the middle of the pool over the cover, it might evaporate off and that can cause water to drop a little. Do these covers not allow any evaporation?

I also read that with mesh covers, they allow a lot of junk and sunlight to pass through, making the water quite dirty - and my water is looking pretty dirty now. I can also see through it quite easily if I hold it up to the sky. I can also push water very easily through it.

I'm sorry for all the questions. I've just had a big fear of a leak for months now and I was really hoping I was wrong.

 

[Pool_Medic]

You state pop up studs, that’s a safety cover. Two kinds, mesh or solid. If solid, nothing or very little passes through it. Your dropping water screams leak somewhere. Usual suspects are skimmer, light niches and returns.

 

[Annorax]

Ah, got it. There are pop up studs so it's a safety cover as you say.

It's not solid though, as I can easily push water through it (if I detach part of it and push it into the water) and I can see through it if I point it to the sky. Water is also resting above it in the middle of the pool.

Based on that, is evaporation still a likely possibility?

 

[Pool_Medic]

Definitely you are losing water.

 

[Annorax]

I meant, based on my type of cover, do you think it's more likely a leak or evaporation?

I apologize for my inexperience and I might be wrong, but even though my cover attaches via studs, I think it's a mesh cover and rain/snow go through it and pool water easily passes through it, plus water is resting on top of it in the middle. I've read several things, some saying covers reduce evaporation entirely and others saying mesh covers don't do very much to reduce evaporation as they are porous - especially if water is resting in the middle, it will more easily evaporate there, pushing more water through it. Personally I think evaporation makes sense, but if my inexperience taught me anything it's that I'm often wrong, lol, so I want to hear from the experts.

 

[Pool_Medic]

Yes, it is a mesh cover, it shouldn’t be resting on the water though, it should be adjusted taut with the straps all around the pool. There shouldn’t be much evaporation if any. Have you opened this pool yet?