Refill Pool-cya ?

[JFS]

Just drained 17K plaster/gunnite pool in SoCal because of high calcium hardness (620). Intended to drain 75% but fell asleep at the switch and drained it almost completely.Taylor test kit shows no measurable CYA. I use tri tabs and I am supplementing with liquid to keep chlor levels up. Should I add some stabilizer, if so how much,or do I just wait till tabs build up enough conditioner in the water.

My PH 7.6, TA 100, FC 3.

Thanks-Joe

[chem geek]

For every 10 ppm Free Chlorine (FC) added by Trichlor, it will increase Cyanuric Acid (CYA) by 6 ppm so it will take quite a while before you build up the CYA using this approach. If you used some Dichlor as your chlorine source for a while, then for every 10 ppm FC added by Dichlor it increases CYA by 9 ppm so will build up faster and it will dissolve right away. Of course, you could get pure CYA, but that takes a while to dissolve though hanging it in a sock over a return or having it in s skimmer sock or T-shirt in the skimmer will have it dissolve in 8 hours or so (careful about the skimmer -- it will tend to block the flow so make sure the pump has alternate suction flows from other outlets such as floor drains or a bypass skimmer inlet in the pool).

[chem geek]

Yes, you can use a good chlorine bleach such as 6% Clorox Regular as your primary source of sanitizer. However, you'll need some Cyanuric Acid (CYA) in the water so you could initially use Dichlor as your chlorine source. Dichlor is found in pool products such as Chlor-Brite. You would cumulatively add around 30-50 ppm of this product (so probably 2-4 weeks) and then after that you would switch to using bleach and would make sure the Free Chlorine (FC) was at least 7.5% of the CYA level. Alternatively, you could add Cyanuric Acid, but since it takes so long to dissolve, you could use Instant Pool Water Conditioner after which you could immediately start using bleach (i.e. you won't need the Dichlor).

You would need to add the bleach every day or two unless you had a pool cover in which case you could probably add it twice a week. For a more stable pH and for some algae prevention, you could optionally use 50 ppm Borates by adding Boric Acid to the pool as found in products such as ProTeam Supreme Plus or more directly from The Chemistry Store, AAA Chemicals, or on eBay.

You can use The Pool Calculator to figure out dosing.