Surface Scum

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wshale

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Oct 19, 2013
8
Bluffton, SC
I am a 4 year owner of a gunite pool located in Bluffton, SC and have the water chemistry thing down fairly well. I have an issue that is new this year that I haven't seen in previous years. The water surface is covered with clear matter that I can't identify. Attached are 2 pics showing what it looks like. The water is perfectly clear and fairly well balanced (FC=5 ppm, CC=0, TA=100, pH=8.0, CH= 250, CYA=55). I have tried running the 2 speed pump on high and suction set to skimmer for 8 hours, but the next morning the stuff is still on the surface. When I try to skim it off with a net it just seems to disperse into smaller pieces. I backflushed the filter and the gauge reading is 10.5psi which is normal. The filter media has never been replaced or chemically cleaned, but based on consistent pressure readings of 10.5psi after flushing, doesn't seem to need it. It is a gunite pool, plaster, 11000 gal, Hayward 1 HP 2-speed pump, Triton TR-60 sand filter, Hayward CL-220 chlorine feeder. Does anybody know what this stuff might be and how to get rid of it?
 
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Welcome to the forum. :wave:

I am not sure what it is but a remedy that is normally very successful is to simply elevate your chlorine for a day or two and run the pump 24/7 until it clears.

I would bring the FC up to around 8-10 ppm with your CYA of 55 and I bet that will clear it out if you keep your pump going.

I know you didn't ask but your pH is a little high at 8.0.....I would suggest 7.5 or so.
 
Mine here near Columbia has the same thing (overnight), but mine appear to be a little smaller, almost snowflake like. Like you said they break apart, and when the pump runs, after a while they are gone! At first I thought they might be salt flakes since this is the first time I've seen them, and I have salt for the first time too! It doesn't seem to have affected my filter pressure. I back wash about every week or more since getting rid of the excess water due to all the rain we've had recently.
 

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I hope it clears for you wshale, I noticed the reflection of the screen enclosure. I wish I could put something around my pool but the only thing I've ever found is close to $1000 and for my pool that would be silly! When I move to Florida I am buying a house with an inground pool with the screen enclosure! (Hopefully not living in a dream world..) I'm still thinking it's some kind of pollen that sorta forms together like flakes on the water. Mine was also smaller and looked kinda like snowflakes. (great description timerguy) Maybe it's tiny stuff that can float around through screen etc and then gathers together on the surface. Blech.

Timerguy, the second pic was actually from about a month ago. The leaves had just come out and we had a bad storm. I guess they weren't strong enough yet and they ripped and pulled from the tree very easily from the wind. I had taken the net off because the flowers and garbage weren't falling as bad. I saw the forecast before work that day and ran out of time to throw the cover back on. I took a pic of the aftermath the next morning. :-\

Thank God for my leaf net. It will have to go back on around july/august when that idiotic tree starts dropping it's little evil marble-like "pear" things in the pool.
 
wshale said:
In my case it can't be from trees or windblown source because the whole pool is screen enclosed. I'm elevating FC now and running the pump 24/7 for a day or so to see if it clears. Keeping fingers crossed!
Click to expand...

With CYA 60ish, you should maintain the FC between 5 and 7, and never below 5. Since the CYA test is +/- 15 or so, I suggest you round up CYA on the FC/CYA chart for slightly better FC coverage. If you have maintained the FC at the low end for the CYA value, conditions could be ripe for a situation. My first thought, looking at the pics, was white tissue mold. I'm not saying that is what it is, but it is a possibility.

The good news is, as Dave mentioned, raising FC level will kill it (and all organics) , but it may end up that a full on SLAM is needed.

White tissue mold/white water mold is uncommon in chlorine pools unless the chlorine level is kept too low and even then it's pretty rare. Nevertheless, what you describe sounds like white water mold -- tissue-like on the surface of the water that breaks up when you try and remove it from the water. If you determine that it is white tissue mold, SLAM'ing will get rid of it, but you should check for other places it might be hiding out such as light niches or under ladders.
 
I also think it's pollen which has the same "clumping" action in my pool. Unfortunately your screen can't filter fine particles. Most screens are 16 mesh, but even smaller 20 mesh screens have openings that are 841 µm. Pollen is 100 µm or smaller and goes right through.

wshale said:
In my case it can't be from trees or windblown source because the whole pool is screen enclosed. I'm elevating FC now and running the pump 24/7 for a day or so to see if it clears. Keeping fingers crossed!
Click to expand...
 

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