Does Dichlor lose its effectiveness?

[cfclay]

So I had a beautiful pool for two months straight using bleach only, but it starting getting hot and I wanted to raise my CYA from 40 to 50.... With my Dichlor I had from two years ago. I suspected that when I added some two weeks ago (to give my CYA a slight bump) that it didn't seem to have any chlorinating effect.

I used 4.9 oz of Dichlor the last two nights . First night the chlorine was 1 ppm... Second night I don't know... There were storms and I just thought I would add 4.5 again.

Darn it, now pool is looking a little greenish, and I can sweep a little algae in the bottom corners!

Chlorine now is barely .5 ppm. Do I need to actually slam again, or can I just raise my chlorine to shock level (16 ppm)?

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[jblizzle]

Yup, you need to SLAM because you let the FC stay way too low for too long. It should NEVER be allowed to get below the minimum for your CYA level.

You could have tested the FC level about 30-60 minutes after adding the Dichlor to see if it went up to what you expected.

 

[cfclay]

I've started the Slam process once this week, and then again last night. In both cases there was no overnight loss of chlorine (probably the course of 10 hours)

TA:10
Fc: was 5 yesterday morning, brought it up to 20 last night
Cya:50
pH: 7.5


Any suggestions on clearing up water?

 

[pooldv]

There are three criteria to passing a SLAM. Need to SLAM until all three pass, SLAM Process