Algae showing up AFTER we treat? So confused!

[JLMM]

Hi there... I've been reading along and learning how to care for the pool that came with the house we bought in November. The pool hadn't been opened in two years and was completely overgrown with algae. We used our sellers' pool guy and over the course of a couple weeks he cleared out all the algae and got the pool looking beautiful. Since then, though, we've struggled to maintain chlorine. I got the TF-100 and tested a few days ago, and sure enough our FC level was nonexistent, as was our TA. The water was perfect, though - absolutely crystal clear with a CYA of 40. I plugged our results into the Pool School calculator and last night we dumped in the suggested amounts of baking soda, soda ash, and bleach.

(A note on the bleach - I sent my husband to get the bleach and he got very overwhelmed and then came home with something that was less than 6%. We put it in, anyway, just to get things started.)

This morning, I went out to check and the water is now slightly cloudy and it looks like we have black algae on the bottom? The pool needed to be vacuumed, but this doesn't look like the typical dirt that blows in and settles at the bottom.

I just tested again:

pH: 7.2
FC: 1.5
CC: .5
CH: 125
TA: 140
CYA: 55

Clearly I'm in need of a lot more bleach. But I'm still confused about why my water would go from crystal clear to cloudy and why algae would try to bloom AFTER we've started moving in the right direction? Am I doing something wrong?

Thanks!

 

[Butterfly]

You need to SLAM the pool: http://www.troublefreepool.com/content/125-slam-shock-level-and-maintain-shockingl

A pool can 'look beautiful' and be sick. You are headed in the right direction, but you need to find stronger bleach/liquid chlorine to do the job easier. Based on you CYA, SLAM FC level is 22. Make every effort to maintain that as often as once an hour but at least twice daily.

You can read about Black Algae in Pool School, and your pool was a good candidate for it. Be sure to remove lights from the fixtures and clean out niches and scrub every nook and cranny in the pool. Algae loves to hide, too.

Can you post some pics of what you think is BA?

Welcome to TP

 

[JLMM]

Unfortunately, I can't post a photo because my husband went out and brushed/vacuumed the pool and now declares that there is NO algae and I'm overreacting.

It was black and in speckles across a lot of the pool floor. It was heavier in a few places, and in those places it almost looked like it was dirt with a long shadow, if that makes sense... There was a portion of it that was slightly lighter. And it had a fuzziness to it in those heavier spots.

 

[JLMM]

And thank you for the very quick response, by the way!

 

[Beens]

It's very important that you get your FC up either way. 1.5 is too low for CYA 55 and is inviting algae to come back in! Make sure you get some chlorine in there ASAP if you haven't already.

If you think there's a problem lurking you can bump your chlorine up to your SLAM level (22 as per butterfly's post) and try the OCLT (Overnight Chlorine Loss Test) and see if you pass.