I've been reading for a couple of weeks now to work out our problems. We've always had a good relationship with this pool for the past 10 years but this year we need some counseling!

Details:
35,000 gal. in-ground (lazy L)
vinyl liner
300 lb. sand filter
skimmer, drain, 2 inlets, 1 light
15 yrs. old

When we bought this house we went to our local pool guy. Everyone does. He immediately recommended tri-chlor and we bought it. We've had no problems, but have noticed we were going through a LOT more tabs and it had been escalating for 3 years. They had changed packaging/size/brands during this time so I thought that was it.

This year we opened to algae for the first time. We've had a hot spring and use the mesh cover, plus due to work schedules we opened late. To top it off our opening was wonked - we couldn't get the pump running for almost a week. I had been throwing in small amounts of di-chlor in the meantime to at least raise the chlorine a bit. Circulation started, water sample taken to pool guy, many $$ spent and instructions followed. 3 weeks later we have to leave for Europe (to work) and the pool is still slightly green. Left instructions for our nephew to follow... which he didn't. Upon our return we found a full-scale swamp that actually hatched dragonflies. We found our problem had gotten out of control due to a filtration problem. Changed the sand. Took MANY samples to pool guy. Spent many more $$. Took more samples in and pool guy shakes his head. We've beaten it down to slightly green, more like a milky blue, but pool guy says our water samples look fine therefore it should be clear. He then rents us a second (cartridge) filter to help clear it faster. $100.00 later we're still in the same boat.

Meantime I'd been reading the forum and when I returned the filter I purchased a Taylor test kit. Pool guy becomes somewhat aloof at this point. I also purchased bleach and borax from Wal-Mart. My initial tests after 7 containers (1.42 gal) of bleach were:

FC: 10
CC: 10
Ph: 7.6
TA: 200
CYA: 100+ (probably 120-150 range)

We gave this a wait and see and continued to maintain, brush and vacuum. No significant change. After more forum reading we decided to bite the proverbial bullet and do a partial drain. We did that on Sunday and spent most of yesterday refilling (to get water trucked in we would have to go through aloof pool guy which I'm not willing to deal with at this time). I tested and figured I'd need to add 6 containers of bleach. Did that last night. The morning reading today are:

FC: 20
CC: 20
Ph: 7.8
TA: 260
CYA: 56 (hooray!!)

The water is uniformly blue and less milky, simply a bit cloudy. For the first time this season I can see barely see the bottom of the deep end. No green tint except for a bit at the deep end which seems to be filtering out. I know from the "shock chart" that we can let the chlorine fall some and still remain at shock level, so we're probably good there. Is it time to try to take the TA down? I know I could stand to lose some of the Ph as well. What else should we do at this point?