losing a 1/2" a day, possibly from waterfall.

gspitz · May 30, 2011

as the title says I am losing 1/2" everyday.
here is the info, IG plaster pool with an attached IG spa, that is 2 feet higher than the pool. Spa has a waterfall overflow into the pool. the waterfall is about 3 feet wide and I have pretty decent flow over the waterfall with some splashing off the brick pool edging.

If I bypass the spa when I run the filter, so feed from the skimmer or pool drain, and return to the pool jet or pool drain (yes I can return to the pool drain) I only lose about a 1" of water a week. If I include the spa, feed from the skimmer or pool drain, and return to the spa. I lose about a 1/2" a day. now I have a crack in the spa plaster(I learned the hard way that you shouldn't leave a paster spa empty in 100 deg weather) that leaks some water, and a tiny leak coming from one of the spa jets. If the I don't run the spa, I lose about a 1/2" of water a day out of the spa. Spa dimensions are about 2 1/2' x 4 feet, so I think that is about 36 gallons a day. If return to the spa, I lose about a 1/2" a day out of the pool in stead of about 1/7". at a 18'x48' pool I calculate is about 2500 gallons instead of about 700 gallons. So could I really be losing 1764 gallons a day out of the waterfall? I can see almost all the spa plumbing ( i have dug it all up to fix previous leaks) and there are no leaks, so if not the waterfall, where could the water be going?

I am not even sure if 1" a week is an acceptable loss for our pool, but that is about the lowest I have been able to get it since we bought the house and it was losing 4" a day. is there a way to calc. what the evaporation should be so I can know for sure that I am losing water somewhere else?

Thanks and any help will be greatly appreciated
Grant

Voodoo_Pool · May 30, 2011

Grant,

This may not be an unusual problem. Please perform the "bucket test" as described in: pool-school/leak_detection

After that, let us know what the results are and we can go from there. Mahalo.

gspitz · May 31, 2011

I set a bucket on my steps today. I should have the results tommorrow...

I was told the water will evap, more or less depending on how deep or shallow your pool is. Is this true cause it doesn't really make sense to me. I always thought it was the same amount per square foot, depending on temp, sun, shade, humidity, alt, ect., but not volume or depth of water.

which i would guess is why the bucket test is accurate?

Voodoo_Pool · Jun 1, 2011

You are correct to suspect the advice you were given about evaporation. The bucket test works, I have used this method more times that I cared to in order to verify a leak in my own pool. Once you verify a leak (or no leak), you can better troubleshoot the root cause. Good luck and let us know how everything works out.

gspitz · Jun 3, 2011

So I filled the bucket, marked my water level, and set it on my pool steps. My wife calls me the next day at work. "So I'm guessing the bucket full of water in the pool is so you know how much water is leaking out?" I respond "Yes, what happened to it?" "Well your son
(thats what she calls our english bulldog when he is in trouble) was very appreciative of the giant water bowl he thought you left for him in the pool!"

so needless to say that attempt was inaccurate. So I refilled it yesterday, and in 24 hours I lost 5/16 of an inch out of the bucket.
I only lost 5/32 out of the pool with the filter running to the pool only, not the spa... and I lose 1/2 of an inch if I include the spa.

now either my test is again inaccurate, or the color of the bucket matters( which I doubt, but my bucket is black and my pool is white).

Is it possible that a black bucket would retain more heat that a white one, resulting in warmer water, more evap. with such a small amount of water, a few degrees higher might make a noticeable difference, but I think thats pretty thin!
I was also wondering if shade or sun matters, I don't think so since with the filter running I would think the pool would stay a pretty even temp all around.

Voodoo_Pool · Jun 3, 2011

My recommendation is to perform the test three times (24 hours each). Once with the pump on and the spa isolated, again with the pump on and the waterfall flowing, and finally with no pump and the spa isolated. This should narrow down the culprits. Clearly the bucket does not have a leak.

My story, because I have had to chase several leaks. I had a leak that showed up in my neighbor's yard some 200+ yards from where the leak originated. I had a crack in the deepend skimmer (previous owner did not perform a proper repair). This incident validates that you never know what is going on under the surface. So - check your yard and your neighbors' yards for soggy spots.

Hope this helps. And I hope you find your leak.

madwil · Jun 3, 2011

with the bucket sitting in the pool, the pool water will maintain it (mostly, maybe not 100%, but 99.9999%) at same temp- that's why it works- keeps almost all the conditions the same in the bucket as in the pool so evap should be the same in both places; if you lose more out of bucket, it's your son's fault (love the bulldog!). If more out of the pool, I doubt its your son's fault- its a leak!
You might want to do the bucket test with the bucket in the spa also- temps can be different between spa and pool, and cause difference in evap.

anonapersona · Jun 3, 2011

But the waterfall skews the results.

I notice that my waterfall has many pools that spill over. Each is rather low when the waterfall first starts, so there are many gallons left in the pool which are evaporating when the flow stops. If we run the waterfall a lot, there is a huge amount of evaporation from all the rocks and splashing and whatnot. If we don't run it, it gets overrun with algae. I never have been able to work my way around the bucket test when the waterfall is on at all, it just messes with the results too much.

We had American Leak Detectors come check our pool for leaks, they test all the lines, including the one to the waterfall. What no one can test is the integrity of the waterfall itself. The joints could leak or maybe it just evaporates a lot of water. In our waterfall, I notice that all the pools do hold some water at the end of the day, so they don't leak too bad if that is where the loss is. I also wonder if the water is flowing around the lip of a rock and getting back under everything that way. One day I'll put a bead of clear silicone on the lip of that rock to make the water fall off and not flow around the lip.

gspitz · Jun 4, 2011

I will do the test more, and with the pool in 3 different setups. I think the waterfall is allowing a lot of evaporation, but the amount seems like a lot... Is there a way to calculate the amount of evap for running water at a given temp per square foot or something?? I know it wouldn't be accurate, but at least it could show a general idea.

Also, with pump on, but spa isolated I never get air in my filter. but if I include the spa by returning to it only, so still only feeding from the skimmer or pool drain, I gather air in the filter tank, like in a 24 hr period it will take 30 secs to let the air out of the filter tank. Is there anyway to get air into the filter by switch the return and not thew feed, I was under the impression that air in the system meant a leak in the feed or at the pump. I only ever feed from the pool and not the spa, so I don't really see why returning to the spa instead of the pool would cause air to build in the system.