Indoor Chlorine targets

[conehead396]

The therapy clinic my wife works at has a indoor therapy pool that is
12 X 8 X 4 ft deep, with a 33" by 12' section that is 6' deep. I figure it is about 3000 gallons by the pool calculator.

What is the chlorine and stabilizer targets for an indoor pool. I used my TF 100 kit and got the following results. At first it had zero chlorine. I added some to get by until I geta better idea of what needs to be done.

PH 6.9
CL 4.0
CC 1.0
Alk 190
CH 600
CYA (waiting until I replace water for CH before checking)

What target should I shoot for on the CL and CYA after I get the CH in order.

Thanks

 

[frustratedpoolmom]

The appropriate FC level is based entirely on the CYA level of the pool - refer to the CYA chart. For indoor pools a CYA of 20 is recommended and it's not necessary for it to be any higher. So if the CYA is higher than 20, determine the FC accordingly. If you are replacing water for the CH to come down the CYA will be lowered as well.

 

[conehead396]

Thanks, I was thinking 20 for the CYA, just wanted to be sure....

 

[CaOCl2]

The therapy clinic my wife works at has a indoor therapy pool

You need to confirm if this pool falls under any sort of "public/commercial" regulation - if so then you must follow whatever regulation applies to that class of pool with regards to residual disinfectant, water balance, record keeping etc.

I think this forum deals with private, residential installations.

 

[frustratedpoolmom]

Good point, definitely look into local laws where applicable.

 

[JasonLion]

Your PH is very low, TA is too high, and CH is very high. You don't generally want to swim when the PH is below 7.2. It isn't particularly dangerous when the PH is low, but it can be irritating, especially on your eyes. Because the TA and CH levels are so high, you don't want to raise the PH too much until you get the TA and/or CH levels down, otherwise you could develop calcium scaling.

What water temperature is used in this pool? Some therapy pools are practically hot tubs, while others have more typical swimming temperatures. Hot tub temperatures will change what you need to do a little.

We tend to make recommendations based on residential pools, rather than commercial, but talking about commercial is alright. For commercial pools it helps to point that out a few extra times, otherwise people can miss that and make suggestions more suited for residential situations. Also, for commercial pools, it is extremely important to be aware of the local regulations related to water chemistry. Some locations restrict allowable levels significantly, while others hardly seem to care. Because of issues like these, putting your location in your profile can help us give you better advice.

 

[chem geek]

Two words: bather load. That is the biggest difference between a typical residential pool and a commercial/public pool. If the bather load is high, then especially for an indoor pool you are likely to need supplemental oxidation of some kind (ozone, UV, non-chlorine shock, etc.) since chlorine alone will have a hard time oxidizing fast enough without being at a level that creates more volatile disinfection by-products. We've even seen some indoor pools with lower bather loads that needed extra assistance to control combined chlorine (CC) and odor -- one user added a UV system which solved that particular problem. Others have managed OK without so it's unclear what the difference is, at least for the low-bather load situations.

If you don't have specific regulations to follow, then for indoor pools I'd go with a 4 ppm FC with 20 ppm CYA target which is higher than what is normally recommended for outdoor pools. This is to have a higher oxidation level of chlorine since you won't have the UV from sunlight helping you out. If regulations forbid your use of CYA, then use the lowest amount of chlorine allowed by law which is probably 1 ppm if you can maintain that consistently everywhere in the pool (might be hard to do under higher bather load or with children urinating though it sounds like children may not be using this therapy pool).

 

[conehead396]

Thanks everyone else for the advice. The local government did a initial inspection 10 years age and has never been heard from again.

The pool is heated to about 90 degrees.

After replacing most of the water the new test are..
ALK 140
FC 3.5
CC 0
CAL 80
CYA 70

I know the high CYA is still a problem and I will have to raise the FC to match the chart.
They had been using stabilized chlorine and I guess with such a small pool (3000 gallons) the level must have been off the chart to still be so high after replacing 75% of the water. We are going to replace a foot or so a week until it gets between 20 and 40.

Don't want to replace more than that at one time because it will cause downtime waiting for the pool to reheat.

Thanks again for the help.

 

[CaOCl2]

Various posts have been removed because they contained personal attacks, or could be read that way, and were not contributing to the discussion. Therefore, this post is a little out of context. JasonLion

It remains a good point - asking why the clinic is not doing the maintenance. Liability insurance comes into play here, who is liable should something happen?

 

[conehead396]

I agree it is a legit question. Maybe I misunderstood the context it was put in.

I maintain their pool pumps, filters, etc, and do other handyman type jobs when needed in my spare time.

I am on the payroll as a part time employee.