Swimming pools blog

40×20 IG pool. Sand Filter. Not sure what my problem is. Maybe
someone here can help. We did a poor job covering our pool last off-
season and had tons of debris in the pool when we opened this year.
Leaves, pine needles, dirt. In any case it took me several weeks to
get it all out. The pool has never really been clear. I’ve brought
water samples in and they tell me its in good balance. Three weeks
ago I changed the sand in the filter and the pool seemed to be
clearing. Then 4 days later we went on a 10 day vacation. The
chlorinator ran out at some point during our trip and the pump
wasn’t circulating the water very well. When we came home the water
was a yellowish green. It appeared that most of this algae had
settled to the bottom so I vacuumed the shallow end to waste and
could see the floor. I scrubbed the deep end, loosenind up the
algae and ever since I can’t see two feet into the water. My test
strips are showing no chlorine.

1. How do I get the chloring up? I’ve added 12 bags of shock in 3
days and 2lbs. of yellow algae out.
2. Are these problems indicative of a filter problem?
3. When and for what reason would a filter need to be replaced? As
far as I can tell it just holds the filter media so if it seems to
be working inefficiently its probably the media that needs
replacing, and not the entire filter, correct?