BLOB in the pool

SRQGP

Member
Jun 15, 2024
15
Sarasota, FL
A couple weeks ago I noticed a greyish-brown blob, sort of mudlike, in one spot in the pool. After the usual cleaning, it was gone, but then it came back a week later in the exact same spot - in a section of the pool that is a shelf, about 3 - 4" deep. Cleaned it, Ok, but then a week later, it was back again. It was cleaned again 4 days ago, and today, it showed up again - same exact spot. The photo I took is not very good, but I wonder if anyone has a guess as to what's happening?
 

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A couple weeks ago I noticed a greyish-brown blob, sort of mudlike, in one spot in the pool. After the usual cleaning, it was gone, but then it came back a week later in the exact same spot - in a section of the pool that is a shelf, about 3 - 4" deep. Cleaned it, Ok, but then a week later, it was back again. It was cleaned again 4 days ago, and today, it showed up again - same exact spot. The photo I took is not very good, but I wonder if anyone has a guess as to what's happening?
See if you can scrape some of it off on a paper towel. Looks like a stain of some kind.
 
Pool was cleaned yesterday. Around 9 AM today it was still clean. At noon I took this photo of the Return of the Blob. It's a fine white powder. If I disturb it, it reaggregates into the brownish blob. Very strange, View attachment 604587
Do you have jets that push water onto that ledge? Might be dirt collecting there.
 
It's worse than I thought. It's no longer just in that one spot - there are patches of this stuff all over the pool bottom. I scooped some up into a clear jar - and I see nothing. But if I touch it, it is slimy. Printout of readings yesterday:
CHEMICAL READINGS
CHLORINE5.0ppmSALT3650ppm
pH7.8ALKALINITY100ppm
CYA60ppmFILTER PSI19
CHEMICALS ADDED
MURIATIC ACID0.20gallonSTABILIZER2Pound
PHOSPHATE TREATMENT2ounce
 
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It's worse than I thought. It's no longer just in that one spot - there are patches of this stuff all over the pool bottom. I scooped some up into a clear jar - and I see nothing. But if I touch it, it is slimy. Printout of readings yesterday:
CHEMICAL READINGS
CHLORINE5.0ppmSALT3650ppm
pH7.8ALKALINITY100ppm
CYA60ppmFILTER PSI19
CHEMICALS ADDED
MURIATIC ACID0.20gallonSTABILIZER2Pound
PHOSPHATE TREATMENT2ounce
Is that test from a pool store? If so, that’s the first thing you need to do is get one of the recommended test kits and test everything yourself. If you read through the site a little bit, you’ll find that pool stores have a very poor reputation of accurate water testing. If it’s slimy, it’s likely algae caused by inadequate chlorination
 
It's the test from our pool maintenance company. THey're practically living here lately - our heater failed, then after that was fixed, our filter pump was leaking. Now this. The Chlorine was 5 ppm - isn't that a bit too high, rather than inadequate chlorination. Pool's only 6 years old.
 
It's the test from our pool maintenance company. THey're practically living here lately - our heater failed, then after that was fixed, our filter pump was leaking. Now this. The Chlorine was 5 ppm - isn't that a bit too high, rather than inadequate chlorination. Pool's only 6 years old.
Read through the pool school And you’ll find out that adequate chlorine is dependent on how much sanitizer is in the water. So five parts Vermilion might be at the very low end of minimum or it may even be below minimum if the water is over stabilized. Best advice I can give is to get, one of the recommended test kits. Unfortunately, pool services are usually not any better at testing than the pool stores.

 

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Good Idea. Did that, and absolutely no coloration or any particulate matter on the paper towel. I then tried multiple volumes and still nothing. I'll try to get a coffee filter from a neighbor & see if that shows anything - that probably has a smaller pore size than a paper towel.

This is the deep end of the pool now. IMG_6831.jpg
 
Good Idea. Did that, and absolutely no coloration or any particulate matter on the paper towel. I then tried multiple volumes and still nothing. I'll try to get a coffee filter from a neighbor & see if that shows anything - that probably has a smaller pore size than a paper towel.

This is the deep end of the pool now. View attachment 604668
How are you chlorinating and do you have a CYA measurment?
 
The CYA was 60. Our pool is serviced weekly by a pool maintenance company that is not affiliated with a pool supply store. They add chemicals as needed. No automatic chlorination. Funny thing - I noticed this morning that the paper towel I filtered the water through had a tiny insect wing in it.
 
The CYA was 60. Our pool is serviced weekly by a pool maintenance company that is not affiliated with a pool supply store. They add chemicals as needed. No automatic chlorination. Funny thing - I noticed this morning that the paper towel I filtered the water through had a tiny insect wing in it.
What type of chlorine do they use? Does their test kit measure over 5ppm free chlorine?
 
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