White cloudy water

Out of town for a week, pool ran out of chlorine, came home to green lime soup. Added tablets to auto chlorinator and 5 gals of liquid chlorine as a shock and ran filter all night. Next day hand vacuumed on waste. Chlorine still seemed low, so added another 2.5 gals of liquid CL. Pool is starting to clear up, but is white cloudy. Have backwashed several times. Do you ever need to replace the sand in the filter? Friend said to add 2 cups of DE to skimmer, then backwash the next day. Will this help? Is my problem even filtration? Thanks

Dead algae is hard to filter out.

If you can vacuum to waste (common with sand filters), after ALL the algae is dead, try turning the pump off, and letting every thing settle.

Using DE can help, somewhat, but it can also make things worse if your filter is low on sand, or coupled with an over-sized pump.

If the algae is not 100% dead, consider putting your filter on "recirculate", and bypassing the sand. The reason is, when the algae goes through the sand, but is not filtered out, it can be broken up into even finer particles that are hard to get rid of.

Do all these things:

1. Get a local OTO/phenol red test kit (yellow/red drops) and hold the chlorine in the orange-ish yellow rage ( > 10 ppm) till ALL the algae is dead.

2. Order a K2006 kit (Amazon link in my signature) so we tell what the chemical conditions in your pool actually are.

3. If you like add 1 -- just 1 -- dose of clarifier and/or floc. But NO MORE! Overdosing can make things much worse. Do NOT use these till the algae is dead! Do NOT use more than the label recommends. If you use floc, you MUST follow label instructions.

Doc, Thanks for the advise. The algae is dead and appears that most is gone. What i have now is a very fine silt looking stuff. When it settles it is almost black, not the brown you see with dead algae. It is like the filter is not stopping the fine particles. Someone told me that sand can wear out where the particles get smooth and rounded. Is this true? Would replacing the sand help? Thanks again for the assist. -bb

That old claim that sand wears out has been around for years, but I've never seen any evidence that it's true.

What does happen is that pools are build with undersized filters and oversized pumps, which (a) forces dirt THROUGH the filter and (b) causes sand loss on backwash. Check your filter's sand level. If it is low, (a) refill and (b) install a valve between the pump and filter and throttle the flow back, to maybe 1/2 of normal. Then, vacuum your pool.

Most sand owners will tell you just the opposite: Old sand filters better than new sand. As more junk clings permanently to the sand and doesn't backwash out, it actually filters MORE than new sand. I'm in my 11th season with the same sand, and our other long-time sand owners have gone much longer. I do add a little DE after I back wash, and use skimmer socks, especially in May and June when the pollen is very, very heavy. The sock catches the pollen, so much that it looks like yellow spackle!

I did have to replace my pump this season, but not my filter or sand. Went with another 1hp 2 speed Hayward Super Pump.