Ok, I have to admit, I'm new to the sand game. Our old house had DE. Even still, I haven't been doing pool maintenance for 6 or 7 years now. So I'm a bit rusty.
Our pool was extremely dirty this spring. It had been left open all winter, filter never ran after initial fill in early September. The PB came and dumped a lot of chlorine, fired up the pump, cleaned out all the big debris with a leaf bag and over a week or two kept vacuuming until clean. I then took over the job.
Every few days, I've had to vacuum out dirt as we still have a lot of unfinished area around the pool. This has been fine until the last 4 times. I'll get it all clean, it looks great. The next morning, about the same amount of junk is back in the pool, settled in the corners and vinyl seams. This is way more than the "normal" amount that was getting in before. So, I'm almost positive that it's just going right thru the filter. PB says that's life with a sand filter, even though HE was the one who convinced me a sand filter with zeobrite was just as good as DE. So I tried adding enough DE to raise my pressure 1psi and vacuumed again. Same result. I also put a knee high around my vacuum plate to make sure it caught anything big I vacuumed. That caught a ball of junk about an inch around. But I still have the fine stuff returning to the pool. I swam down and put my finger on it and it scatters like crazy as soon as my finger gets close. PB says my only option is to vacuum to waste as sand will never filter out this small stuff. Is this really true?
For those who are curious, this is how the pool looked this May after they shocked it back to clear water -