Indoor pool with UV light to kill DBP ?

[SPP]

Dear Seniors,

Here is a scenario.

I realized that indoor pool can be headache to maintain properly due to air circulation and no sunlight to breakdown disinfection by products.

I keep reading Richards writing on CYA/FC relation and so on over and over again, and bit by bit I am beginning to understand, hence more questions. coming.

Does it make sense to add UV sanitizing lamps in an indoor pool filter plumbing to reduce chloramine or whatever combine chlorine it can remove. Other option is buy indoor illuminating lamps that can generate UV like how they do "green house" plant growing...well something like that. Of course air vent is a must for good air flow.

UV sanitizing lamp will also kill FC along with CC, but by how much ?
What I am trying to day dream is, how do we get an indoor pool to be as safe and pleasant as an outdoor, as far ad natural sunlight not being available there. We don't discuss air exchange.

There are buildings that the indoor pool is located as such sunlight can only come from side windows and not from the top.

Just brainstorming here.....

Thanks guys.

 

[Guest]

My understanding is that UV is a useful addition to an indoor pool to help reduce chloramines. However, as you noted, there are drawbacks also. Perhaps Richard will jump in with more info.

 

[chem geek]

Unfortunately, we only know what doesn't work very well which is that most indoor pools do not use CYA and many have problems with chloramines both registering in the pool water and smelling. Also, the respiratory and ocular problems are with indoor pools. What is not known is how much of this is due to the poor air circulation and lack of sunlight vs. not having any CYA in the water.

I know that pools with no CYA are generally over-chlorinated (because there is no CYA to moderate the "active" chlorine amount) and I know that this will lead to more nitrogen trichloride being produced from chlorine oxidizing ammonia. Nitrogen trichloride is the smelliest and most irritating of the chloramines. What I don't know is what will happen to urea. Not enough people have tried using a small amount (about 20 ppm) of CYA in their indoor pools for us to know how effective that would be to make managing such pools easier with less smell and better control of Combined Chlorine (CC).

There have been reports of some with UV systems that say it helps to control CC, but others say it doesn't help that much and reduces FC so you have to add more to compensate. Generally speaking, UV systems are primarily used to inactivate those pathogens that chlorine doesn't handle very well -- namely, the protozoan cysts including Giardia and especially Cyrptosporidium. As for oxidizing organics including getting rid of CC, an ozonator does a better job BUT it also tends to use up FC. There are some indoor pools using SWG systems and they tend to not report seeing CC, but without CYA some have reported metal corrosion of stainless steel within a year.

So the short answer is -- I don't know. My gut feel is that the use of some (but not too much) CYA would be beneficial, but I don't know if it will help with the CC since it all depends on what kind of CC it is -- that is, whether it's a chloramine or chlorine combined with an organic.

Richard

 

[PoolOwnerNumber9]

"how do we get an indoor pool to be as safe and pleasant as an outdoor"?

Properly done, ozone is one of the best options for an indoor pool. The cost is quite high to design, engineer, install and operate a good system, but it gives great results. Ozone would help to avoid problems with trihalomethanes and chloramines.

Another possible option is using bromine.

 

[Guest]

Another possible option is using bromine.

Although bromine is often advocated for indoor pools it still has it's share of undesirable disinfection byproducts.

 

[PoolOwnerNumber9]

"Although bromine is often advocated for indoor pools it still has it's share of undesirable disinfection byproducts."

I agree. Indoor pools are a particularly difficult challenge. Also, it has been my observation that many operators do not use bromine correctly, and that greatly increases the problems related to bromine.

 

[SPP]

Thank you all, gentlemen...