How Safe to Swim?

[mmcwhorter]

I noticed someone said in another thread in the Forum "Its safe to swim up to SLAM levels".....and I assume that means any SLAM level associaed with any CYA level. That gets in to levels above 35 ppm with CYA at 90.

Yet for ever and all time I have read "Do Not Re-Enter The Pool Until CL level is Between 1-3 PPM.

So, am I to assume the mean nasty "pool industry" not only wants us to buy all their products we don't need, but to also keep us out of our pools???

What's the truth here?

 

[Donldson]

As with everything involving the pool industry, they do not take the FC/CYA relationship in to account. Case in point, a pool with a CYA of 90 and FC of 35 has a lower active chlorine level than a pool with no CYA and 3 FC. This is why an indoor commercial pools tend to be extremely harsh on skin, hair, and swimsuits while maintaining a much lower FC level than most TFP pools.

The industry has ignored the FC/CYA relationship for the last 40 years, don't expect their advice to change just because we come along with all of our "facts" and "peer reviewed studies".

 

[Texas Splash]

You pretty-much nailed that on the head. Pool industry recommended chlorine levels mean nothing to us since TFPC takes into consideration each pool's CYA level. As long as the FC and CYA are compatible or in-line on the Pool School - Chlorine / CYA Chart, you are fine. Basic rule is that it is safe to swim as long as the FC is between the minimum and SLAM FC level for your CYA. With the higher FC it may be best to rinse your swimwear after use, but all-n-all it is fine.

 

[pooldv]

We did a swim-n-slam a few weeks ago. Cya at 70 and FC 25-28. For about a week and a half. No problems at all, couldn't even tell. And it was a lot cooler and easier to brush every day!

 

[mmcwhorter]

I kind of figured that...the CYA and FC relationship....And that's really good to know! It's been hot herein Southern MD and I was using the pool after the SLAM was completed ....as the FC started to drop from above 35 toward the 10 or so I want to keep it at...

Thanks everyone. This is an awesome web site. I now have 10 gallons of 8.25 bleach, 2 boxes of Borax and two boxes of store brand Baking Soda in my chemical deck box. Paid way less than one item at the pool store would have cost me. Whooooooooooooooo hooo.

 

[chem geek]

What's even worse is that the ignorance about the chlorine / CYA relationship means that many commercial/public pools not using any CYA (including most indoor pools) are significantly over-chlorinated. Because they are only looking at the CYA level they think that anything below the EPA limit for drinking water of 4 ppm FC is OK even with no CYA in the pools. Even a pool with only 1 ppm FC and no CYA has over 16 times the active chlorine (hypochlorous acid) level of pools at our recommended minimum FC/CYA level and is even 67% higher than at our normal SLAM level.

Or put another way, the range of active chlorine level in an indoor pool with 2 ppm FC and no CYA to an outdoor pool with 3 ppm FC and 100 ppm CYA is a factor of 80 yet the industry thinks that because the FC levels are similar that the pools are the similar chemically. In the indoor pool they are significantly over-chlorinating while in the outdoor pool they are under-chlorinating.

The only issue with a higher FC level would be if you were to drink voluminous amounts of pool water since then it is the chlorine capacity as FC that is relevant for its total effect -- the rate isn't so important. The EPA limit of 4 ppm is based on 2 liters per day so with 35 ppm FC this is 229 ml or drinking about 1 cup of 35 ppm pool water every day for the rest of your life. So don't do that. :lol: