chlorine levels

[Whidster]

I was talking to a friend who runs a dog rehab pool. It is indoors. Her pool place recommends she maintain a chlorine level of 1 ppm. A google search indicated a recommended level of 1-2 ppm.

Your site recommends 2-3 ppm (I assume my FC of 5 is the equivalent of 2-3 ppm?)

Why are your recommended levels higher?

How does the FC translate to ppm?

Thanks.

 

[zea3]

Most pool places do not take the chlorine/CYA relationship into effect. The higher your CYA, the more chlorine you need to effectively sanitize the pool.

All measurements are ppm, so your FC of 5 is 5ppm.

Your friend needs to maintain the FC according to the size of the pool and how much CYA (if any) is in the water. I assume there are human handlers in the water with the dogs. If so then the water will need to be maintained at levels safe for human use. Dog hair will be full of bacteria, saliva, urine, feces, and anything else they have gotten into, so the FC must be high enough to oxidize those contaminates for the pool to be safe.

 

[Bama Rambler]

Even with an indoor pool, unless the AHJ (authority having jurisdiction) expressly prohibits it, they should have about 20 ppm of CYA in that pool and keep the FC at the top of the range recommended here for 20 ppm CYA. They should also have a supplimental sanitation system like UV. {I assume this is a licensed business}

As Zea said, all our measurements are in ppm except for pH.

 

[JasonLion]

CYA greatly reduces the active chlorine level. An indoor pool with no CYA and FC of 1 has an active chlorine level roughly equivalent to an outdoor pool with CYA at 50 and FC at 25. So your pool actually has a much much lower active chlorine level than your friends pool.

 

[chem geek]

Or put another way, the active chlorine (hypochlorous acid) level in pools following the Chlorine / CYA Chart is the same as in pools with an FC of 0.06 ppm FC with no CYA for the "Minimum", 0.10 ppm FC with no CYA for the "Target", and 0.6 ppm FC with no CYA for the "Shock" level.

My wife who swims almost every day has personally experienced this effect because she uses an indoor community center during our 5-month winter season where the pool has 1-2 ppm FC with no CYA while during our 7-month summer season she uses our own outdoor pool that has 4-6 ppm FC with 40 ppm CYA so on average is roughly the equivalent of 0.1 ppm FC with no CYA. In the indoor pool, her swimsuits last only one season where the elastic degrades and her skin is flakier and hair frizzier compared to using our own pool. Also, in our pool, her swimsuits last for multiple seasons with no sign of degradation. The difference can be attributed to the 10-20 times higher active chlorine level in the indoor pool.

Dogs shed a lot more organic matter that needs to be oxidized compared to humans. So the chlorine demand is going to be high in such pools. By using CYA in the water to buffer the active chlorine level, one can have a higher FC to not run out of chlorine while not having the active chlorine level get too high. For an indoor pool, having 4 ppm FC with 20 ppm CYA may be a good balance. Note also that without sunlight hitting the pool, supplemental oxidation will likely be needed such as using a UV system or adding additional non-chlorine shock (MPS).

 

[Whidster]

WOW! You guys are amazing!

So, since I'll be swimming 3 hairy GSDs should my Target FC remain as follows:

Cya. 30
FC 5

We are adding an SWG soon. So...

Cya 60
FC. 4

 

[chem geek]

For an indoor pool, especially with a higher bather load, having a somewhat higher active chlorine level can help speed up oxidation somewhat. However, this isn't a big deal and you can use the standard Chlorine / CYA Chart as is and see how that goes.

However, for an indoor pool, you do not need a higher CYA level because there is no sunlight to breakdown chlorine. So 20-30 ppm is sufficient. There is no need to go any higher than that even with an SWG. So just target the FC to be somewhere in the 10-20% of the CYA level, mostly because you've got the dogs. If the bather load were much lower, then you could have the FC be lower, but I really think you're going to need the higher FC and somewhat higher active chlorine level. Again, you will likely need a UV system or supplemental oxidation to control Combined Chlorine (CC).

 

[Whidster]

Thanks, Just to clarify the indoor dog pool if not mine. I was just chatting with her and wondered why she had a lower chlorine level than I maintain.

my pool is outdoor. I have a lexan dome that will be open in the hotter months and does allow indirect sunlight even when closed, much like a greenhouse.

Our bathing lode will consist mainly of about 4 adults ands and 5 dogs.

That being the case what would you recommend for my FC and CYA without a SWG?
Cya. 30
FC 5

We are getting a SWG in a few weeks. What should my FC and Cya be then?
Cya 60
FC. 4

 

[JasonLion]

You go by the same target levels everyone else uses. The trick is that the minimum target is what you want the FC level to be the next time you go to check the level and add more chlorine. With more people/animals in the water you may need to raise the FC level higher to start with, so that it is still at least at the minimum the next day. The best way to figure that out is to try it. After a couple of days you can usually zero in on just what levels you need to use.

 

[Whidster]

Thanks Jason. We had such issues balancing the Baquacil it will be a relief if this is easier to maintain. My husband hooked up a pump and pvc pipe to aerate the pool to help bring the TA down. Just waiting for the FC to drop enough to swim the dogs and warm it up to swim myself! Can't wait.