Help - major algae now cloudy pool

[14me2]

To an extent, old sand is good, but take it from experience... I have wasted a lot of time and money trying to let it filter itself, as my parents never changed their sand that Iknow of. I know this is probably untrue, but we have had our pool for 5 years. We used the same sand forever, then all of a sudden we couldn't get the pool to clear. It was a beautiful color, but not sprakling clear... we tried everything, finally we changed the sand. Clear in 2 days!! Fast forward to last year, We had not opened the pool the previous summer... due to a sickness. We had everything right, but the water was grey. We tried floc, and drop out and super blue and tons fo others miracle things, but the cheapest and fastest of them all was jsut some good ol fashioned sand. It looked better over night. And the price of that sand was jsut a bit more than the bottle of drop out. So, I mean what's the worst thing that could happen.

ETA: After a while there will be little channels of sand in your filter, this is not doing anything to filter, (it looks like ants live in there) but allowing it to make it right back into the pool. If you treat your sand at the beginning and end of season, then yes your sand will last longer, but most people don't and relaly it is just as easy to go ahead and change it yearly. Sand will harden and the the water will have to flow somewhere, so it makes the channels....