Quick question

[Mags®]

Been shocking for a week now and I am still losing a lot of chlorine overnight. Example, last night after the sun went down my FC was 24.5 This morning, it was 12 The pool is crystal clear other than a few spots of black algae that won't die. Will that much clorine be lost to those few spots of black algae?

cc = .5 as of last night
cya = 40 as of yesterday
Ph has been rock solid at 7.4 the whole time.

Let me know if you need any other numbers.

 

[benavidescj]

You need to keep that FC level at shock level the whole time. At night the only thing that will make the FC drop is organics. Since you had a large drop at night you need to keep shocking. The reason why it may be taking longer is that you need to MAINTAIN the shock level which in your case is 16ppm. Since in the morning your FC was at 12 it fell below the shock level for your CYA level of 40.

 

[Mags®]

Ill keep a close eye on it, just seems a lot of chlorine loss for just a few spots of algae. Don't know what else it could be though.

 

[Bama Rambler]

Are you brushing that black algae with a metal bristled brush? If not you should be.

Are you testing after dark and before sun up? A few minutes can make a difference.

 

[Mags®]

yes and yes

 

[Flotsam]

Bama - should a bristled brush be used on plaster?

Mags - what kind of brush are you using? What is the stiffness of the bristles? How old is the plaster?

I'm using a fairly soft bristle brush on old plaster that really should be re-plastered. I'm careful to not over-brush the exposed blemishes ... which leads to a nagging question that I have that requires a seperate post - looks like I'll be posting sooner than later. Sorry - didn't intend to hijack this ...

 

[Mags®]

It is a stainless steel 6" brush. If you take it off the pole and use it by hand scrubbing real hard, it will break up the outer layer of crust on the black algae, otherwise the algae laughs at it... The bristles are stiff, but the algae is tougher! The pool was replastered 3 yrs ago and is in great shape. I believe my issue is I left it alone for too long and didn't ever combat the issue. The pool is crystal clear with these spots hanging on. I'm letting the FC level drop down to a non shock level and am going to jump into the pool and tackle it that away. Only real option I have at the moment. :?

 

[JasonLion]

Stainless steel brushes are fine on plaster when the plaster is more than one year old.