I don't think this is algae but I've vacuumed it up several times...

[tturkstr]

Thanks in advance for moving this to a more appropriate forum if I picked wrong.
Strange phenomenon when I opened my pool this year. When I removed the safety cover, there was some fine silt-appearing brown dirt on the bottom, and a few leaves.

1. I shocked the pool and vacuumed up whatever it was, but it came back the next day. It definitely seems to be "settling" out of the water, also collecting on the seams across the sloped part. Interestingly, the filter pressure went up when I did that first vacuum so I backwashed it per usual. Now back to 10 PSI.
2. Chemistry is good with pH 7.2, FC:5, CC:0, Ca: 200, TA about 1.7 kg low but I'm just about to add that. NaCl at 2700 and I just added a bag since I usually run around 3000. Borate will bring the pH if the alk adj doesn't.
3. I vacuumed it up a 2nd time, but about a day later it was back again, almost as though it was getting dispersed through the water and then resettling.
4. It's also hard to vacuum since it disperses before getting vacuumed up if you move the vacuum too fast.
5. I tried my robot, but I can see the stuff going right through the robot and getting fired up through the robot exit port.
6. I left it for a few days and it didn't get any worse, so it does not seem to be growing.
7. Lastly, I tried adding 1/4 cup of DE to my sand filter hoping it would catch finer particles. No apparent change.

Ideas on what this is and how I can get rid of it?

Thanks for your thoughts,

 

[proavia]

What is your CYA?

Please post test results fertically to make them easier to review.

FC
CC
pH
TA
CYA
Salt
Water temperature

Do an Overnight Chlorine Loss Test to rule out algae.

What test kit are you using?
Add it to your signature

 

[tturkstr]

Sorry about that:
FC 4
CC 0
pH 7.2
TA 60
CH 200
CYA 10 (just added CYA)
Salt 2700
Water temperature 60
Overnight Chlorine Loss Test only lost 0.5 and CC is 0.
So I don't think it could be algae passing the OCLT and CC of 0. But I don't know what it could be. Hopefully someone will recognise what's in the pictures or has had something similar in the past.

 

[duraleigh]

I am pretty sure you are seeing DEAD algae on your pool floor. That's very common.

Most of it should vacuum up into your filter if you are careful You may even be able to brush it up into the water and your filter will capture it

Run your pump around 10 or so hours daily to help with filtration.

Post back if it quickly reappears