scared of cya? Magic target?

[roth79]

My numbers this morning are:

PH 7.8
FC 5.5
TA 60
CH 275
CYA 60
Temp 90
Salt 2800

When I first found this site my cya was way up there, Pucks, I drained and balanced, got swg etc. I am slowly adding cya and am uptight of going to high, but I was at 40 a few weeks ago. I'm looking for that magic CYA number, in southwest florida with full sun all day long. I am getting different target levels here while reading and the pool calc. My Pentair 40 in a 13000 gallon pool is on 80% running 8 plus hours to get to the 5.5 FC I have today. I do add liquid when it drops as the swg is working hard now at that percentage.

What do you think a good target is a 90 degrees Florida sun all day long with no screened in enclosure?

As always Thanks for the great advise,

Roth

 

[Butterfly]

70 to 80 CYA is recommended. Try 70 and see how that goes. You can always go to 80 later.

 

[Donldson]

It's not so much a magic target, more a compromise between sun protection and needing higher levels of FC.

I second Butterfly, SWG in Florida 70-80 is a good range. That should help your SWG maintain your FC around 5 ppm.

 

[[email protected]]

Higher than 50? The website http://www.tps.com.au/pools/chlorine.htm says "It is recommended that you maintain a residual of 30-50 ppM of CYA. At 25 ppM the chlorine will last 3-5 times longer. Above 50 ppM, no marginal stabilization benefit is observed."

 

[linen]

Welcome to tfp, [email protected]

Be careful when you read information put out by manufactures with "skin in the game". Also, they have no references on that web page to show the data behind their claims. With that said, it is only with Saltwater Chlorine generator (swg) pools that we extend our recommended range up to 70-80 ppm cya. In non-swg pools, a cya level of 30-50 ppm is our recommended range.

If you want to read in more detail how CYA protects chlorine from sunlight, start here: http://www.troublefreepool.com/pool-water-chemistry-t628.html#p4494 Be careful in there...it is the "deep end" of the forum

 

[chem geek]

What they wrote is simply not true. The reason some in the industry say there is no benefit above 30 ppm or 50 ppm (depending on who you talk to) is that they are referring to high bather-load commercial/public pools. In those pools, most of the chlorine loss is from oxidizing bather waste, not from loss from sunlight. So some CYA is needed or else the sunlight loss is indeed high, but with just some CYA such loss is significantly reduced below the higher loss from bathers. So it "seems" like adding any more CYA doesn't help. Also, a higher CYA without a proportionately higher FC can result in algae growth and that increases chlorine demand even further.

In residential pools, the bather-load is very low so by far most of the chlorine loss is from the UV in sunlight so higher CYA levels help to reduce such losses, even above 50 ppm. In fact, we've done experiments showing that a higher CYA of 80 ppm is beneficial for saltwater chlorine generator pools to reduce their chlorine generator on-time which helps reduce the rate of pH rise in such pools.

You will find a lot of misinformation about pools and spas in the industry. Check out the Pool School to learn the truth of what really goes on and how to maintain your pool.