I have a 26,000 gal pool with a salt generator. This is our 4th year and I suddenly can not keep chlorine in the pool. I have been using the BBB - putting in gallons of chlorine.

Latest test results:

Free Chlorine: .4 ppm
Total Chlorine: .8 ppm
Combined: .5 ppm
pH: 7.4
Hardness: 317
Alkalinity: 106
CYA: 58 ppm

PHOSPHATES: > 1,000
NITRATES: 90 PPM

I had a new sensor put in my salt generator, have boosted twice and am running at 70% and still can't keep chlorine!

So the recommendation is to drain the entire pool and re-fill with fresh water!

We are going away for a week, so I plan to add an algaecide, shock the heck out of it and run the system until we get back. Does this sound like the best approach?