Chlorine level not remaining stable

[gnhand]

Basic info - I use Taylor k-2006 & pool math; location of pool Long Island NY ; 18000gallons semi inground pool; new liner put in in the fall ; pool was opened by a professional two weeks ago ; two days ago I took over pool and after pool math added 1 gal of liquid chlorine stabilizer to raise CYA from very low (~15/20) to 30.
My readings:
a)on 5/13 fc = 1.8; Cc.5 ; CYA 30 ; PH 7.4; ALK 70; CH 50 temp 74
Added 40 oz of 12.5 liquid chlorine ; 17 oz bicarbonate of soda ; 68oz calcium chloride flakes
B). 5/14 9am FC 3.4 ; CC .2; CYA. 30
C. 5:14 at 5:30 pm - FC .4 ; CC 0.0 ; CYA 30; PH 7.4; ALK 80 ; CH 130

Tonight I put three stabilized 3” chlorine pucks (Leslie’s) into an automatic chlorinator.

I plan to raise the CYA to 40 tomorrow when I can get more stabizer ( liquid) - natural chemistry Brand- instant stabilizer

Does anyone have a suggestion of how I should proceed. I’m a relatively new member from last year. Is liquid stabizer ok to use - not worried about the additional cost of the product, as I won’t need very much.

 

[IceShadow]

Why are you raising your CYA more? 30 is pretty good for now. How does the water look?

 

[gnhand]

Crystal clear. But from this morning to this afternoon the FCfell from 3.8 to .4. I thought it might be because the CYA wasn’t to the ideal level of 40 That what pool math suggests.

So my real question is - how can I get the chlorine level to maintain around 4-5 without drastically dropping during the day??

 

[mknauss]

You will lose 2-4 ppm FC each day from UV impact. You need to add that back each day.

 

[gnhand]

You will lose 2-4 ppm FC each day from UV impact. You need to add that back each day.

Thanks - are there unstabilized chlorine tabs that can be put on an auto chlorinator? I thought that CYA keeps the chorine stabilized so I wouldn’t have to add every day?

 

[mknauss]

Thanks - are there unstabilized chlorine tabs that can be put on an auto chlorinator?

Realistically, no.
Commercial pools have devices they can load large quantities of Calcium Hypochlorite in and then it premixes it with water to inject. Not for residential use.
Get a SaltWater Chlorine Generator.

 

[gnhand]

That sounds simple.Are they that good and do they last a long time ? After the initial cost is the maintenance ( salt and salt cell replacement) costly?

 

[mknauss]

Lots of threads in Salt Water Chlorine Generators (SWG)

SWG How It Works - Further Reading

www.troublefreepool.com

 

[Bperry]

That sounds simple.Are they that good and do they last a long time ? After the initial cost is the maintenance ( salt and salt cell replacement) costly?

The salt stays in the water and doesn’t get used up (for the most part), but it’s pretty cheap.