Solar Cover coverage and Evaporation

[heweydewey]

Hi All,

About 2 weeks ago I was concerned that I might have a leak. Even with the solar cover on, my pool was losing some water. Air temp dropped considerably those few days (around mid to upper 50's at night) and my water temp was pretty warm (high 80's).

I did the bucket test (24 hours with pump and 24 hours without the pump) and there was no difference in the water levels between the bucket and pool in both cases.

I put the solar cover back on and just to be certain, I checked the level in the pool again after 12 and 24 hours. Water level dropped again 1/16 in 12 hours (during the day 6am-6pm) and another 1/8 overnight (6pm-6am) - a 3/16 total in 24 hours.

Can I assume this is evaporation? I just did the bucket test and it showed no difference in water levels. Now I've read few things searching around that says I should have almost zero loss with cover on and also some saying that it's possible to still lose that much water if you do not have full coverage.

What's considered full coverage? A tight seal all around? My cover isn't a tight seal but he only parts of my pool not covered are the steps, a small area around the ladder, and also the far edge of the pool by the diving board where there is about a 4-5 inch gap between the pool wall and the edge of my solar cover. I also noticed that it looks like some water gets on top of the cover at the ends and travels along the two seams that run the length of the cover (not sure if this is continuos or not). I posted some pics.

[attachment=2:2rqsyat1]steps.JPG[/attachment:2rqsyat1]

[attachment=1:2rqsyat1]far-edge.JPG[/attachment:2rqsyat1]

[attachment=0:2rqsyat1]ladder.JPG[/attachment:2rqsyat1]

Can not having these areas covered allow for that much evaporation when the conditions are right? There's no shade over my pool so it gets the brunt of the sun all day and the only thing around the pool is our vinyl fence. Last check before this pool temp was at 80 and yesterday was pretty cool day around upper 60's at high point of the day, about 55-60% humidty and winds around 9-10mph. At night the temp dropped to about 55-56, humidity around 48% and winds around 12-14mph.

Any thoughts? Thanks in advance.

 

[Bama Rambler]

Unless you have a leaking bucket, the bucket test is pretty much bullet proof if done according to the instructions.

Since you have done the bucket test twice and it hasn't shown any difference I'd say that you don't have a leak. However, that does seem like a lot of loss on a 99% covered pool.

 

[heweydewey]

Dave, thanks for the reply. It puts my mind at ease a little.

I'm pretty sure I did the bucket test right and also did check at 12 and 24 hours.

When I saw the loss overnight I was freaking out a little. Seemed a bit much even with the cover. My previous losses I was noticing before the bucket test were not quite so dramatic, maybe about 1/16 inch over 24 hours. Maybe the weather conditions were just right.

 

[Bama Rambler]

I've seen my pool water evaporate a lot at night when the temp gets down and the humidity is really low. It literally creates a fog coming off the pool surface rising into the air.

 

[heweydewey]

I don't think my fence is a great wind barrier. It's just that fence around the pool and the house on one side of the pool. Other than that, it's all open. Also, it rained the night before and when I made my starting level marks, I did notice alot of water settled on top of the solar cover. Maybe alot of that can account for my loss.

Just to see, this morning I actually covered most of open areas with plastic sheeting to get better coverage. Keeping fingers crossed that it helps.

Also wanted to say thanks again. I've had alot of questions this summer and you've frequently replied and helped me out. It's been greatly appreciated (as well as all the other help from TFP)!

 

[mikespoolfl]

Are you removing the cover completely when you measure? I know when removing my cover some water comes out with it, some water get’s on top also and evaporates. Not sure how much.

 

[heweydewey]

Mike,

No, I measured with the cover on. In hindsight I probably should have taken the cover off and let the rainwater on top of the solar cover run off into the pool before i made my starting level marks. There was quite a bit of water. Mostly pooled up down the seams running the length of the cover.

[attachment=0:uhem0x8g]top-cover.jpg[/attachment:uhem0x8g]

 

[heweydewey]

Just a quick update. My pool was still losing water with the cover on - probably about 3/4" in a week with the cover on the entire time. Was just about to throw the towel in and call someone to check it out so I decided to clean the pool last night before I made the call.

Well, God must have been looking over my shoulder last night because I found a 1/4 inch tear on the pool wall! Noticed a dented spot in the pool and followed it up the wall to the tear. Don't know how I missed it!

It's all patched up now - hoping that was the only tear.

I marked the water level in a couple spots and in 12 hours the water loss was between 0"-1/32", depending on which level mark I checked. Is that acceptable range with the cover on? Hopefully, I can write this one off as a done deal.

 

[Bama Rambler]

I'd say that 1/32nd of an inch is too low to even measure accurately. I'd call it nothing.

 

[heweydewey]

Awesome. Thanks Dave.

I can't wait to go home and erase all the pencil marks on my skimmer and stop worrying about it!