I guess I'm going to throw the question back to you: it depends on whether you want to run a high CYA pool or not.
Read the Best Guess page linked in my signature. If you keep the high CYA, you'll have to run the chlorine levels shown. It scares some people to run FC that high, though there are no ill effects on outdoor pools that we've been able to discover. And you tend to use less chlorine, and certainly don't have to dose as often with a high CYA / high Cl pool.
Personally, I'd run high CYA, high Cl, rather than dumping all the water. But it's up to you. The 'classic' BBB method I developed assumes lower CYA levels.
You'll either have to run the chlorine levels shown OR lower your CYA. If you want lower the CYA, you'll need to replace 1/2 of your pool water. If you do drain, do so safely. Inground vinyl pools can't be drained without professional help; inground concrete pools in low or wet areas can 'float' out of the ground, destroying the pool. AG pools shouldn't usually be drained completely -- but 6 - 12" of water left is usually safe.
Bookmarks