u/wantogodeeper

Appreciate any advice with identifying and eliminating some mysterious gloop that has appeared in my pool this season.

The pool is 4 years old, regular family use, quite a lot of leaf drop when windy (eucalypts mainly). salt chlorinator part of pool equipment.

The gloop is small greeny brown particles that accumulate and aggregate on the floor of the pool, which disperse when disturbed. I can see that there are suspended particles also, but not so many to affect pool clarity overall.

I have assumed and treated as algae as follows, but unsuccessfully:

1. Algaecide (and separately Copper Quat for mustard algae) treatment for 24 hours after scrubbing floor and walls. Vacuum to waste, backwash and rinse. Disappeared, then returned.
2. Increased sanitation / Cl level to 750-800 ORP (5 ppm) for 2-3 days. Scrub, vacuum and backwash/rinse.

After 2-3 days the gloop reappeared.

Pool shop analysis not revealing, pH 7.4, phosphates 0.

I need to winterise the pool shortly but would like to resolve this issue first. Thanks for reading.