CYA 0 Recommended Shocklevel for INDOOR pools

[Zadd]

Since my indoor pools have a constant CYA level of 0; what is the recommended shock level?

 

[Leebo]

Re: CYA 0 Recommended Shocklevel

We suggest still raising the CYA level to 20-30 then shocking to 11-13FC level. There are several benefits to having CYA in an indoor pool and unless you are not allowed by state inspections (public pool) we suggest adding some.

 

[Bama Rambler]

Re: CYA 0 Recommended Shocklevel

If you truly have zero CYA the shock level is 10 ppm.

As Leebo said, having a little CYA in an indoor pool is a good thing.

 

[JasonLion]

Re: CYA 0 Recommended Shocklevel

For an indoor pool that has never had any CYA, shock level is technically 2. However, if you are actually fighting algae, 2 ppm of chlorine is simply not enough, it will be used up way too quickly. So it kind of depends on why you are shocking the pool and also on how quickly you need to FC level back down to something swimmable. For serious algae or major CC problems, 10 is good number. But for minor issues or anything done routinely instead of in response to an issue, then 2 to 5 makes more sense.

Keep in mind, that everything I'm saying here only applies if there really really isn't any CYA. Even very small, impossible to measure, CYA levels mean shock level is 10, and none of the lower numbers apply.

 

[Isaac-1]

I am on a pad so will brief Chem Geek has written on the benefits of use of limited levels of cya in indoor pools I suggest you read Some of it.

Ike

 

[Leebo]

Here's one such quote....

As FPM noted, if you don't use any CYA at all and use an FC level of 2-3 ppm as you suggest, then compared to the 4 ppm FC with 20 ppm CYA that we recommend you've got 10-20 times as much active chlorine (hypochlorous acid) in the pool which will oxidize swimsuits, skin and hair up to 10-20 times faster and also likely produce about 10-20 times as much irritating and volatile nitrogen trichloride. The significant reduction in active chlorine when CYA is present is not a bad thing unless overdone. Essentially, pools with no CYA are over-chlorinated unless they have very low FC levels which is what the German DIN 19643 standard tries to achieve (but such low FC levels could "run out" of chlorine under local bather load conditions).

The downside to the lower active chlorine level is that it takes longer to oxidize bather waste and when there is no UV in sunlight to help you it's possible to build up more CC, at least temporarily. Indoor pools are a challenge and often need supplemental oxidation (UV or ozone) unless the bather loads are very light and this is true even when no CYA is used.

 

[chem geek]

Zadd,

Given your CPO question in this post, you should take a look at Certified Pool Operator (CPO) training -- What is not taught.

If your pools are commercial/public pools, then per this code for Texas and its related attached graphic, "*Stabilizer shall not be used in indoor pools or spas or brominated pools or spas". Unfortunately, Texas regulators do not understand the chlorine/CYA relationship.

 

[Zadd]

These are public use facilities and I am required by the state code to not introduce CYA into the water. I am also required to keep clorine levels at 2-3 ppm. To add to the challenge I have no automation so my bromine tablet feeders are adjusted daily. To further add to the challenge we host regular swim meets of 200-400 athletes. I appear to be stuck between this rock and hard place.

Ill re-read the CPO material you suggested. Ill also look into UV systems for extra oxidation. Maybe the universal aquatic code will have better practice standards and my state will adopt them. Thanks for the help.

 

[chem geek]

Supplemental oxidation will be key for your pool. You might look at non-chlorine shock during heavier bather load to reduce disinfection by-products, though it's more expensive than chlorine. A UV system will keep chloramines lower. Ozone is another alternative though requires special care to prevent outgassing, especially for an indoor pool (i.e. they usually degas the ozone before the treated water is reintroduced into the pool).