Leak or evaporation?

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NjPool84

Well-known member
Jun 9, 2017
65
Hackettstown, NJ
Hi,
A little history on my pool...Please stay with me :)
I live in North West NJ. Our new IG pool build started last September (dug, built, filled, covered in December. By February I noticed 20-30 inches of water loss. I struggled to keep the 5 dollar wal mart crummy tarp that the cheap pool builder provided in place and intact but it was torn up within a week. TLDR; After battling with the electrician and the pool builder for weeks, it was discovered we had a leak in our wet niche (light housing). We dug it up and saw it spraying water out of the top. Pool builder replaced it. While filling it back up, I observed for a day or so whether it sprung any more leaks in that area. The conduit line was also partially dug up and exposed. No leaks. No ground saturation.

We filled that hole with sand, then dirt. Built the patio. All good.

A near drought of a summer in NJ with 90-95+ degree temps all summer. I was losing 1/4 - 1/5 inch per day so I was filling up 3-4 inches once or twice per week between early July and late august. Out of caution I did multiple bucket tests and observed the water level dropping in the bucket along side the water in the pool. It was just evap. Other neighbors reported similar situations with water loss. I also purchased a dye injector to detect leaks. Tested around the pool light housing, as many corners as I could, 99% sure I tested the main drain, all fixtures (returns, skimmers etc), steps... nada. All good.

End of August rolls around... water loss slows down significantly. We get some rain into september. I don't think I added water to my pool once in September...water loss simply stopped it would appear. We had a little rain here and there, but it was well below average still. We close the pool up September 30. Hired someone to do it this first time because he was also installing the pool cover.

Pool cover is solid with a mesh square in the center. According to the guy who installed it, it is supposed to have some sag and is designed that way so water can drain toward the center and into the pool. So it isn't as tight as a solid cover (like my last IG pool).

Yesterday, something told me to look under the cover. Bam...20+ inches of water gone again. Now, the water is absolutely frigid!!! If I had to guess, 40-50 degree range. However, the ambient air under the cover was really really hot, you saw droplets of water on the underside of the cover. I took the cover partially off and performed more leak detection in areas that I could (stairs, corners, reached down to the light...all good. I tried to get into the deep end to do the main drain, but it was too cold. Im currently doing another bucket test with the cover on again. I have also not seen any ground saturation, heaving, cracking, dips, or any muddy areas anywhere near the pool. I have grass growing, finally, despite the drought. The concrete around my pool is also looking great (no heaving or heavy cracking where it should be).

So what can it be? Is it possible that I had/have two leaks in a brand new IG pool that has seen ONE season? Or could it be evaporation at the tune of a half inch a day considering that it has been relatively mild in NJ in October and now November (40-60 degrees with the last 4 or 5 days being over 70..yesterday was nearly 80).

If we understand what evaporation is... a different in temperature and pressure from water to air. If the water is frigid (40-50 degrees) and the air under the cover is hot as heck...plus a little but of air getting under the cover, could this cause enough evap?


I reached out to the guy who installed the cover and winterized to see if he does leak detection but I think I'll be hard pressed to get someone out here before it really does get cold. I think Im facing a situation of filling the pool throughout the winter as needed if there is indeed a leak or heavy evap (unless water temp/air temp under cover balances out better in the coming colder months).

Thoughts?
 
I can relate as I have just become the proud owner of my first pool leak. :( Pressure side plumbing. You are correct that the larger the variance between water and ambient temp the more potential for loss to evaporation. Still, a 1/2 a day is quite a bit. Since you are closed, returns and skimmer are all plugged & secure so the only two areas that could be suspect (besides the liner) would be the main drain and/or a light niche. In that cold water not much you can do right now, so I suspect monitoring the water level may be your best option. You might get lucky when air temps come down. Time will tell. In my case, the dye test wasn't conclusive, but once I plugged my jets all water loss stopped. In your case, all plumbing except the drain is out, so it would appear to be more of a structural issue (liner, light, steps, etc).
 
Update on this..Filled up pool again. In the process of another bucket test. The bucket did lose some water over a 24 hour period, maybe half inch. The pool lost about two inches. However, when I popped open the corner of the cover to look there was a massive amount of steam and water vapor that came rushing out for several minutes. You could see it and feel the moisture. It was, again, quite hot and humid under the pool cover where as when I began the bucket test, it was not. Over the weekend when I noticed the water loss, it was hot and humid.

Likely its a leak, but man this also feels like a substantial amount of evaporation too. My pool is still in full sun from 8am until it gets dark, around 5:30-6pm here in NJ. It has been mild to unseasonably warm/hot over the last week or two. Yesterday was the first seasonable day of November.

I think Im going to keep an eye on it, keep filling where needed. Close my indoor spigots soon but re-open just to fill the pool once or twice a week. and when we are in the heart of winter with consistant 20-35 degree temps, cold air...I'll really pay close attention to water levels.
 

Leak or evaporation?

Hi, A little history on my pool...Please stay with me :) I live in North West NJ. Our new IG pool build started last September (dug, built, filled, covered in December. By February I noticed 20-30 inches of water loss. I struggled to keep the 5 dollar wal mart crummy tarp that the cheap pool...
www.troublefreepool.com www.troublefreepool.com

I no longer think it is a leak.

See the previous thread I posted back in November shortly after we closed out brand new IG pool.

Throughout the winter, I regularly observed .5 inch of water loss a day. This was reliable and consistent as I planned a filling schedule around this water loss rate so that every two weeks I will open a spigot, drop a hose in for 4-5 hours, and know exactly where the water level would be and when I need to refill in order to keep the structure of the pool safe throughout the winter. I generally liked keeping 3-4 inches on the top step as a guide. Also note that we did have a relatively mild winter (it barely dropped below 32 degrees here in NJ...a few times but nothing like in previous years). We didnt have any snow (maybe a few inches in one storm, thats it. Hardly even dustings). I dont think we had much rain either. Any time throughout the winter when I would open a corner of the cover, you saw massive amounts of steam escaping. It was HUMID under the cover, at least 80+ degrees it felt while the water was very brisk (it froze over .5inch once or twice on the surface, but generally it was probably low 40s).

I opened the pool on May 5. Easy start up, very little to clean. Filled the pool up to just about the top of the opening of the skimmer.

The next day (saturday) I started the bucket test with pool water scooped into a large home depot bucket placed on the first step. I marked the water line in the bucket. I marked the water line in the pool on the face of the skimmer. I also took measurements how deep the water was in the bucket and how deep it was on the first step. (5 inches on the first step in the pool, 11.75 inches in the bucket).

I could not easily notice ANY water loss in either pool or bucket for the first two days. It wasn't until Tuesday that I noticed a small difference but it was in the bucket, not the pool. If anything at all, the bucket was losing more water than the pool and measurements overall stayed the same. I ended the test after four days with results that do not scream leak, but scream evaporation. I observed a reliable 1/8 inch per day which is totally fine to me and is a far cry from .5 inch per day in the winter.

Since then, almost two weeks have passed (this Friday/Saturday in two-three days will be two weeks). I just measured the water in the top step and its down to just over 3.5 inches deep (which is just less than 1.5 inches of loss) and the same is true from the mark on the skimmer that I had made. I don't feel the need to fill up the pool again, and in two days I suspect the same will be true. By Saturday I might have a total water loss over 14 days of 1.75 inches vs where I expected to be with .5 inch per day over the winter ... I expected to be down 7 inches and re-filling the pool.

tldr; I will still perform an extensive visual inspection of the pool in a few weeks along with a leak detector ink injection kit. But I do not think I have a leak anymore. I do think its just a heavy amount of evap. The pool is in full sunlight from about 7am until 6pm. In the fall and winter (even yesterday still) it is VERY VERY windy here. We regularly get 30-40 mph gusts. Im in an elevated position. I see wind getting under the cover all the time and billowing it up and down like its breathing. The cover has a mesh square center.

I know .5 inches of evap during the winter sounds a bit much for winter evaporation and would go against traditional wisdom on the subject, but I don't see another explanation how I was losing that much over the winter, with the ambient air under the cover steaming hot (literally see the steam rushing out), humid as a jungle... and then once I open the pool and introduce the cold water to the some-what chilly air...water loss stops.

I hope this helps anyone else experiencing the same. Traditional wisdom says evap is 1/8 - 1/4 inch per day maximum but I think my case is probably an outlier considering the conditions and factors for the pool location and set up. Hope this helps!
 
I will of course continue to monitor and if I feel that Im losing more than I should, Im repeating the bucket test and might have to drop the 500-700 for a diver. No one in my area seems to want to dive into a pool, ever and upcharges me when I request a dive.
 
Texas Splash said:
Appreciate the update and that you appear to have avoided a leak scenario. How about we just combine this update to your previous thread? You can always update it later as needed.
Click to expand...
I was going to but the little blurb at the bottom of the page of my original post said it was an inactive thread and might not get a lot of traction. This is fine too!
 
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Hello! I'm bringing back this thread, because...well, here we are again!
Just closed the pool on Wednesday (3 days ago), and have lost 1 to 1.5 inches of water which is precisely consistant with what I lost per day last fall/winter at a half inch per day. See the above portions of the thread.

Before people read water loss at a rate of .5 inch per day and assume leak, Im here to tell you no... against commonly accepted wisdom.

Zero, zero, zero water loss all summer. I may have had to fill the pool an inch or two maybe 3 or 4 times total from May through Oct 1. We had heavy rain in June, nearly no rain from early July through mid august. It was a normal rainfall season. Still, I did not observe ANY, ZERO, water loss all summer. In fact, the preceding four days of the pool being open Sunday, Monday, Tuesday and Wednesday we had record high temperatures for October between 75-82 degrees, sunny and dry. No water loss. I watched it like a hawk because I expected this.

The moment we put the winter cover on, 3 days later about 1.5 inches of loss. You tap the cover, you hear condensation falling back into the pool. Its humid underneith that cover. The last temp that I saw with the water was about 64 degrees.

I know its an uphill battle to try to convince anyone that you can lose a half inch of evap during the winter. But Im just keeping this post alive to educate people, its possible. I've done the tests that I can do as a pool owner: Several bucket tests and dye tests, all negative. We never lose anything during season. But we lose a heck of a lot once that winter cover goes on. It is a grey Merlin cover, solid with a center mesh.

Could I simply have the worst cover ever made? Are center mesh covers more prone to evap?

I hope this helps anyone in a similar situation.
 
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