What is a normal level of chlorine loss?

[JABRY5]

I live in Dallas, TX. We've had an unusually hot and dry May.

I keep my CYA around 60 for the spring / summer months, and I have been losing around 4 ppm of chlorine each day. Is this normal? I seem to remember losing around 3 per day last year, even in the summer.

 

[Texas Splash]

Hot down here around S.A. too. A loss of 4 ppm is right on the bubble. Depends on how much swimmers and/or any other potential stress has been on the water. If in doubt, it may be a good idea to run an Overnight Chlorine Loss Test just to be sure algae is out of the equation.

 

[JABRY5]

Thanks Texas Splash. Think I will do that tonight. Good to know it's not totally unreasonable. I recently SLAMed the pool; maybe I missed a spot.

 

[JABRY5]

A related question - does a higher CYA lead to lower rates of chlorine loss? I thought that was the tradeoff - more expensive to SLAM, but cheaper otherwise.

 

[Texas Splash]

does a higher CYA lead to lower rates of chlorine loss?

Ideally speaking - it can. More UV protection less/slower FC loss. However that comes with a price. The ratio of Free Chlorine to CYA is designed to maximize efficiency, ensure sanitation. As you noted, if a SLAM is required, the SLAM-Shock level becomes much higher. Here in TX, much like So Cal, AZ, So NV, it's not uncommon to use a higher CYA than other locations, but we keep the FC balanced per the FC/CYA Levels for that very reason - to avoid algae. Below are some previous discussion. To make sure I didn't misquote something, I'll ask @Donldson for a sanity check.

Picking the most economical CYA level

So I've been reading a lot of the information on the relationship of CYA to FC and the recommendations that higher CYA levels may be beneficial to pool owners that get a lot of sun and thus experience a lot of FC degradation. I haven't seen anyone do a chlorine consumption comparison of the...

www.troublefreepool.com

Adjusting CYA upward to slow chlorine loss due to sunlight?

Hello All, We are about to complete a nearly complete drain to reduce CYA. Yes, we were doing all the wrong things - using pucks! Anyways, I'm hoping to start off with a CYA in the very low end of the recommended 30-50 range. Once we get pool refilled, pH and FC adjusted for the CYA we have...

www.troublefreepool.com

 

[Donldson]

To make sure I didn't misquote something, I'll ask @Donldson for a sanity check.

The last thing I should be used for is a sanity check

So as you increase CYA you decrease the percentage of chlorine burnoff, but as you increase CYA you increase the required chlorine. So eventually as you raise CYA you end up losing more chlorine because you need so much to maintain sanitation. The FC/CYA Levels finds the sweet spot where losses are at a minimum. For manually chlorinated pools, that level is around 50. Since SWG pools have a lower FC requirement that means the sweet spot is higher, around 70. Caveat here that different areas and different pools can benefit from adjusting the CYA level up or down to find the best sweet spot for their pool. While the FC/CYA ratio works as well here in Ohio as down in Texas, the specific CYA level to maintain that sweet spot may vary.