Small brown-green Spots on Pool Floor

[Tjp107]

Good Afternoon,
Small brown-green spots have formed on the floor of my pooland they keep coming back. If I use a leaf rake, they puff up and dissipateinto to water. When I vacuum them, they reappear the next day. I recently useda fine Mesh skimmer sock in my skimmer basket while vacuuming and those spotsstill reappeared the next day. These spots seemed to form on the same places withthe same shape patterns. All this still takes place during a 2-day SLAMprocess as well as before the SLAM. The water is crystal clear. I attempted to attach a photo, not sure if it will show up??

Water Readings
FC – 14 this morning, passed to OCLT test.
CC – 0
PH – 7.5 (was brought down to 7.2 before SLAM)
CH – 100
TA – 90 (was 100 before SLAM)
CYA - 40

 

[setsailsoon]

TJ,

I have no experience with vinyl lined pools so maybe you should hear from others before you do anything. The reason I'm responding is I've experienced almost identical situation with my in ground gunnite/pebble pool. It drove me nuts so I got my dive gear on and looked very closely at what was going on. FC level was always high enough relative to the CYA. So on close examination I found the spots had a combination of good light during the afternoon sun, and they were in a spot between pebbles or some of the tile ornaments we had installed in the surface that were preventing good scrubbing as well as these areas had very limited water flow. I scrubbed them lightly by hand with a stiff brush and the spots never came back. Maybe a fold or bubble in your liner is causing a similar situation. I've theorized the combination of low flow and protection from scrubbing allowed a micro environment where a dead layer of algae was always produced on the surface of the bubble that let's algae inside to thrive after the local FC is consumed. No proof this is the problem yet but it does explain how this could happen. My "scuba scrub" isn't a solution for everybody but it did completely eliminate the problem.

I hope this helps.

Chris

 

[Tjp107]

Chris,

Thank You for the quick response, it makes sense, my spotted area is too indirect sunlight farthest from the filter. There probably is a crease or two inmy vinyl liner in that area. I guess it can't hurt to give it a more detailedscrub.

Thanks,

Todd