OCLT passed vs algae

[gorocket1981]

Hello,

I opened the pool 2 weeks ago. Water was clear with some debris in the bottom, mainly cedar branches and other small particles. When I opened I vacuumed to waste in multiples shots which removed everything I could see. After that I balanced everything. Pool was clear but I did a short SLAM to shock it a bit. I did an OCLT and it passed so I maintained the levels including chlorine.

After some days, I noticed small bunch of brown debris at the bottom at different places. I think it was bunches of sand or similar small particles that deposited in the bottom over time that were probably in suspension in the water. I vacuumed again and cleaned everything but in a short time, like 1 hour after they began to reappear at different places gradually. I continued to maintain the pool. I was still worried. I did 2 OCLT in a row (over 2 days) and they both passed.

For me it seems like small particles that deposit in the bottom and that cannot be filtered. Else than that, water is clear. I am still worried and I don't know what to think.
Is that possible to have this kind of small particles not filtered that forms bunches in the bottom? There is many at different place.

Water temp is really cold, in the 50s. Weather is not so good either. Not that much sun and not hot at all.
Could this still be algae even if OCLT tests are passed and weather is not favorable for algae?

It is too cold for me to go in and see. If I can find skimmer socks, install it and vacuum, could this help identifying the issue?

What can I do?
Thanks for your advice.

 

[mknauss]

I suppose the material 'poofs' away when you brush it?
Good chance it is dead algae. The low water temperature is keeping it pretty inactive and thus you are passing the OCLT.

You can wait until you can capture a sample of it. If it is gritty, then it is sand/dirt. If you smear it on a paper towel and it leaves a green tinge, it is algae.

Or, raise your FC to SLAM level and hold it there for a few days. See if the material goes away.

 

[gorocket1981]

OK. So I could just continue to maintain everything and wait for higher temp and capture a sample to confirm?

If I raise FC to SLAM level and hold it there, if it is dead algae, would they go away over time?

Is it possible that the filter is contamined by algae?

What do you think about the skimmer sock? If I can find this somewhere and I vacuum, would it retain the stuff or it would still pass over the skimmer socks?

 

[mknauss]

You can wait until you can capture a sample of it. If it is gritty, then it is sand/dirt. If you smear it on a paper towel and it leaves a green tinge, it is algae.

Or, raise your FC to SLAM level and hold it there for a few days. See if the material goes away.

The filter is not contaminated with algae.

You can try a skimmer sock. See what you get.

 

[gorocket1981]

And another question following one of your answer.
If it is dead algae that are gradually deposing in the bottom, can dead algae revive with higher temp coming or dead is dead?
If dead is dead, it is less an issue.

 

[gorocket1981]

For sure it degrades the beauty of the water but I want to evaluate how major is the issue.
What I don't know is if there is new bunches falling at the bottom or if it is the existing that are moving.

 

[mknauss]

Not sure I understand. If you are seeing dead algae debris on the floor of the pool, your chlorine is still killing live algal spores in the water and your are seeing the result on the floor of the pool. You can go along as you are or SLAM now to resolve. As I described above.