Rainwater brings algae!

[elsie]

And I have the empirical evidence. This is the first year in the four I've been living in the south, and owning my pool, that we had a significant early summer drought. Virtually no rain week after week after, well you get the idea. Interestingly, I noted that I didn't have the usual summer algae, either. Algae that I long ago decided to ignore because no amount of shocking would get rid of it. I should mention that the few little pockets of the green stuff never made the pool green -- I always have sparkling clear water.

So no algae this summer, then poof, we got our first drenching rain, and within 24 hours I had the little pockets of algae again. Then we had another few weeks without rain, and no algae. Then again got a good drenching, and again the little swirls of green appeared.

Interestingly, I also saw that my pH didn't have the usual rise (using bleach) that it historically does with my pool. Instead of having to add a cup of acid every week, I was going several weeks in between doses. When the rain came, though, the pH immediately rose.

Anyone care to opine on the rainwater-algae-pH connections?

[matt4x4]

Air carries pollutants of all kinds, rain "washes" the air, the waste water ends up in your pool, all this equals food for algae to get a start from.
Always add bleach after a rainstorm and you won't get algae growth and vacuum soon afterwards so the settled out crap won't hang around in there too long, i've been doing that for 2 years and never have a problem.

[elsie]

Ah, that makes sense.

I add bleach every single night, usually two quarts. I keep my chlorine on the higher end -- between 4 and 7 (CYA about 35, need to buy and add a bit more). Still, I get the green swirls (which I do promptly vacuum up but they only come back in a day or two). Since the water's always clear, I truly just surrender to the little swirls!

[mkelley]

I'm really dumb here -- can I add bleach (just household bleach?) to the pool even though I have a salt-chlorinator? Up until now all I do is add salt when it tells me to, and lo and slo (because the Ph is always that way with the salt-chlorinator and a new pool).

I've got some green algea growing in the spa (but not the pool although it's the same water system) and the water's crystal clear but this is the first time it's happened (and yes, on topic, this was right after it rained for the first time in a while here in Florida).

[Watermom]

can I add bleach (just household bleach?) to the pool even though I have a salt-chlorinator?

Yes you can! Many people with a swc also use bleach.

[sevver]

I dose the pool with extra bleach after a rain, as well as after I have a heavy swimming load, and I have not had algae at all since I started BBB. I just figure that the rain caused the algae somehow, so I attack it first. It works for me.

[matt4x4]

Elsie - what kind of steps do you have leading into the pool?
If they are the roto molded wedding cake or elite type stairs, your algae may be coming from within them, the water inside those steps does not exchange often enough, place a couple of pucks inside (one low, one high) and that should cure the green streaks that come back all the time.