Bought foreclosure with in-ground green "swamp" pool

Just saying hello and getting my required first post out of the way. I have made significant progress on clearing up the 21,000 in-ground swamp that was in my new home's back yard, but now it's been a cloudy blue for a couple weeks. I figure it's the dead algae, and the sand filter wont filter it. Still can't see bottom, so I vacuum blindly and getting less and less debris out of deep end each time. Used pool filter cleaner (degreaser) last night and backwashed it out this morning so maybe that will help... Also brushed the walls again.

My "pool progress":
https://lh3.googleusercontent.com/-h...a8/s800/01.jpg

https://lh6.googleusercontent.com/-c...ac/s800/02.jpg

https://lh4.googleusercontent.com/-g...9E/s800/03.jpg

https://lh4.googleusercontent.com/-9...DQ/s800/04.jpg

https://lh5.googleusercontent.com/-J...LU/s800/05.jpg

https://www.facebook.com/aaronprill/...00000379677173

Looking for any other tips to clear up cloudiness. I do see bubbles from my jets every so often, so I'm guessing that's probably not helping. Can't determine where air leak might be though.

Filter is Hayward S200 Sand filter. I'm guessing it was installed back in mid to late 90s at least. No idea when sand was last changed out, so that might be my next plan of action.

I've also just read where you can add some DE to a Sand filter to help it work better. Anyone want to verify that? If so, how much? And to where- the skimmer? I haven't been able to get into my filter without taking out all the hex bolts at the mid-section, but I've just ordered the special Hayward Dome wrench on Amazon that allows the top dome to be taken off... Can sand be changed out with just the dome off (using a shop vac to remove old sand), or should I remove all the hex bolts at the mid section?

Thanks,
Aaron

You're making good progress!

Do these things:

1. Get some DE (10lbs is plenty) and add 2 cups to a skimmer. Watch the pool returns. If you see DE shoot back into the pool, then your filter needs service. If not, you're good to go.

2. Assuming your filter is OK, add 2 more cups of DE to the filter. Back wash the filter whenever the pressure has increased 5 psi over the 'clean' pressure. DE will cause your filter to 'clog' up, much faster, so keep an eye out. Add more DE after each backwash.

3. Using a label dose -- NO MORE! -- of clarifier, will usually help in situations like yours, with dead algae and a sand filter. Do NOT overdose: too much clarifier can work in 'reverse' and make it harder to clear your pool.

4. If you do need to service the filter, I'd recommend opening the shell -- it's not THAT big a job, and you are much more likely to get things fixed properly. Be CAREFUL, when you re-assemble the filter that there's NO sand on the O-ring, or on either the top or bottom O-ring groove. Sand doesn't usually need to be changed, but there are exception. You can take the dome off, and get a sample of sand. If it's in balls or all gummed up and sticky, it should be changed. But, it doesn't really 'wear out'.

Two cups of DE sounds like a lot to me. For the test of the filter looking for blow back into the pool, of course it's right. But generally, for maintenance purposes, 1/3 to 1/2 cup is usually enough in a 200# sand filter. More than that and the filter clogs requiring back washing to get the DE out.

But...you can always add MORE DE to find the ideal level.