How can I tell if I have algae?

[RaceAngel88]

Thanks for the quick response! I have a couple more questions.

(1) I don't want to drain the pool and refill because our well water is AWFUL, and last time I filled a pool (smaller Intex pool that I had) with it I spent weeks trying to filter out white powdery stuff--possibly calcium? Anyway, it was quite a process. So with this pool, I had water delivered from town by the volunteer fire department. I'd hate to have to ask them to do that again, LOL! So if I don't drain and refill, and if my CYA stays high, can I continue to maintain the pool by using bleach and keeping the FC at 8-15? With the high CYA level the FC should drop slowly, so I wouldn't have to be adding the bleach as frequently, correct?

(2) I've been having to backwash so much while I'm vacuuming because the filter pressure rises so much that the vacuum loses suction and the return flow is impeded. The rest of the time the pump seems to be working okay and there's no need to backwash. I ordered some of those "socks" that go in the skimmer to catch smaller particles. Will that help get rid of the finer dirt so that the water is clearer?

(3) If I add DE, how much do I add? What are the pros and cons of adding DE?

[Anonymous [GDPR] European in the UK]

1. If you maintain the free chlorine at a high level it will oxidise the CYA slowly away. Using shock levels it would drop quicker but there is also a bacteria solution that will reduce the CYA level. I reduced the CYA from 200ppm down to 50ppm using high doses of chlorine which also helped burn out the quats and get back into control of the pool, the chlorine was cheaper than the empty/refill process.
2. The filter you have is tiny so it fills with debris quickly hence lots of backwashing. Those socks that go in the skimmer capture the larger particle the sand filter captures the small particles but as I just said yours is too small for the size of the pool, 20" or 24" would be better for that size of pump.
3 you would only need a tiny amount of DE for a filter that size, almost not worth doing, alternatives such as jolly jelly clarifyer work well but won't work that well in a small filter as they catch the dirt it's delicate jell gets pushed apart by the force of the water trying to blast through it. Gently is much better to catch things in the filter.