Rain and algae

[chem geek]

Jean,

Are you using a FAS-DPD (or even just a plain DPD) chlorine test to check separately for Free Chlorine (FC) and Combined Chlorine (CC)? It's possible that the rains (and wind, etc.) brought a lot of organic demand and that what you thought was FC was really CC (if you used an OTO test, you can get fooled that way).

Richard

[CrisL]

I find that by using some polyquat (poly 60 type algaecide) at prevention levels, which is about 2 ounces a week per 10,000 gallons, I prevent the late summer bloom I used to get. I start using it in late July or the beginning of August and use about a quart for the summer. If you buy a larger jug, the rest can go toward closing. I keep my chlorine between 2 and 5 ppm most of the time with cya of about 30.

[jv4nu]

I was using Ben's kit, my CC was never more than 0.5 on any given day. The polyquat sounds like a good idea, I will try some of that next fall.