Not a happy situation here. My pool has had a mustard algae attack. The usual TFP prescription is to measure FC and CYA, and then use the pool calculator to figure out how much chlorine to add to get the FC level up to mustard algae shock levels. FC is at 6.5, and CYA is at 80. As the Pool School course in battling algae says, " If your CYA level is too high, you will need huge amounts of chlorine, which rapidly becomes impractical". Well, the pool is at that point--target mustard algae shock level for the pool is 44 and I'd need to put in 10.5 lbs of 73% cal-hypo or 15 gallons of bleach. I know, mea culpa, mea culpa, my fault the pool got to this point. Forgive me, forum, for I have sinned.
Alternatively, the pool calculator tells me that I should drain half the pool and then refill with fresh water. In any other year, that's what I'd do. Except that this year, California is having a serious drought. Come June 1, we'll be subject to water use restrictions, including a ban on filling pools. Technically, I could still get the pool partly drained and then refilled, but the thought of doing that right now just feels wrong. I really don't want to waste that water, especially as lawns are going brown. Especially as the pool is due for a replaster job, which we are hoping to do in the coming year, which would mean that we'll be draining and refilling the pool at that point.
I'm curious to know what people recommend that I do. Is it worth it to put in that huge amount of chlorine and get the pool up to that high shock level for three days? If I do that, and then put in the requisite chlorine religiously, will that truly keep the mustard at bay for the season? Or, should I just limp along with weekly brushing (I know my habits, there's no way I'm going to be able to do daily battle with it) for the rest of the season? What words of wisdom do the forumites have for me?