Auto pool cover enabling some kind of growth?

[jcapela]

We've had this problem for a while now and wonder if other folks have seen it, too. Our pool was new last summer and at one point very early on, FC hit zero for a couple of weeks. At first sign of cloudiness we got professional help and also started our education in pool chemistry. The treatment was super chlorination and the pool was back to sparkling soon enough.

However, all is not perfect. Every time we open the auto cover, there is a thin film on the water's surface. Not over the whole pool, but mostly it is heaviest near the edge where the cover rolls up. It's an oily looking film that sometimes has white flecks in it. If the pool is in direct sunlight, the film will clear in an hour or so. Aside from the film, the water is sparkling.

One observation is that once the pool is uncovered and open long enough to clear the film, closing and opening the cover results in more film. This leads me to believe that whatever I'm dealing with is on the underside of the auto cover. There also seems to be a correlation with the water temperature - the warmer the water, the more film on cover open.

I've tried scrubbing the underside of the cover with bleach from within the pool. That was a nasty bit of work that didn't clear things up. It may have lessened the amount of film initially, but it's back to where it was pre-scrub.

So, anyone have experience with this? I'd love to know what I'm dealing with. I'd love to know how to treat it. And in the meantime, is it safe to swim?

Thanks,

Jay


35k gallon
CYA=40
FC=3; TC=3; CC=0
PH=7.6
TA=150
Water temp = between 70* and 80*

 

[JasonLion]

Welcome to TFP!

First, it is important for the pool to get a little sunlight even if you aren't using it. A few hours a week should be plenty.

What you describe sounds like organic oils. Raising the FC level a little should take care of it (though not if there is something more serious going on at the same time). With CYA at 40, FC of 3 is the lowest you should ever allow it to get anyway.

 

[YippeeSkippy]

I haven't noticed anything like this under my cover. Could it be pollen that gets under the edge and collects? I do notice your chlorine level is kinda low for that CYA level so perhaps you've got some low level algae living there?

 

[swimcmp]

Jay the auto cover is some to blame. I sell alto of auto covers and what we see is a need to run fc higher than normal, maybe as much as fifty percent for a few days out of a month. We have yet to find anyone that can tell us for sure what it is. We have also found that we need homeowners to keep the pool open to sunlight maybe one to two days of the week to get the uv to it. We have tried a product from natural chemistry that is geared toward a white mold and have had some success with that.

 

[Patrick_B]

This sounds like it could be bacteria growing under there to me, especially if it is growing on the cover's underside. It is a bit of a guess but not a wild one, and it wouldn't surprise me at all based on the description.

 

[Smykowski]

I'd try running the FC higher for a few days. Maybe make 5 or 6 your personal min and see what happens.

 

[raidencmc]

Any chance you have some sort of oil from the mechanics of the auto cover leaking?