Chlorine won't hold in my pool / high CYA level

[jojomo]

Hi, I'm a newbie here and I've done quite a bit of research before posting.

Here's my question, I live in Arizona where the temperature reaches 105-110°F on a daily basis right now and I'm having a heck of a time keeping chlorine in my pool and I have a feeling its because of high CYA levels and not adding enough chlorine.

After having gone through a couple pool guys, who apparently had no idea what they were doing and did not help at all, we decided to take care of our pool ourselves.

Here are the specs

12,390 gallons
Pool water temp - 86°
CYA - 150 (which I know is extremely high)
pH - 7.2
FC - 0.5

We run the filter for 12 hours minimum - Water is clear / no sign of algae

I've switched to using liquid chlorine 10% instead of tabs / shock because i didn't want to add anymore CYA or calcium to the pool (since water is already hard) but even after using 1 Gallon at night time on a daily basis, the pool is still not holding the chlorine. I know its recommended to use A LOT more chlorine in order to shock it effectively but I'm super worried about reaching and maintaining such a high FC level and honestly I don't feel comfortable adding more because I'm worried it may have a negative effect on us (especially my 8 year old) when we are swimming.

So my question is, why do all the sites say that one shouldn't swim in a pool with FC level of 3ppm+ when I keep reading the opposite with high CYA levels?

I know I should theoretically drain the pool and refill (and trust me, I would do this!!! but it's not recommended to do so in the summer, am I correct?) It feels like we are stuck right now and I'm not sure what to do!!!

Any advice would be super appreciated at this point!
Thank you so much.

 

[GOONiE]

So my question is, why do all the sites say that one shouldn't swim in a pool with FC level of 3ppm+ when I keep reading the opposite with high CYA levels?

I know I should theoretically drain the pool and refill (and trust me, I would do this!!! but it's not recommended to do so in the summer, am I correct?) It feels like we are stuck right now and I'm not sure what to do!!!

Industry standard is different than tfp standard. 2 different approaches to pool care. Mind boggling that the FC standards are that far off but it seems to be working for both.

Why can't you drain and fill a pool in the summer?

 

[jeffchap]

The industry doesn't recommend CYA levels above 30, and for that an FC of 2 to 3 ppm would be fine.

With CYA at 150, the minimum FC you need to maintain sanitary water is 11 ppm. And to clear up existing algae, you'd need to raise it to 60. This is nearly unachievable without adding copious amounts of chlorine.

CYA binds with the chlorine and holds it in reserve, thereby rendering it ineffective. So even at 60 ppm, with CYA at 150 your chlorine would be less harsh than 1 - 2 ppm of chlorine with no CYA.

If you truly only have .5 FC in your water, an algae outbreak is guaranteed in your near future. How are you obtaining your test results? They look suspicious, because no test we recommend can measure CYA accurately above 100 ppm. The first step to proper pool care and the TFP method is to obtain one of our recommended test kits and perform yourvown testing. Pool store testing is spotty at best and very often wildly inaccurate, especially with CYA.

 

[jojomo]

Hi Jeffchap,

Thanks for getting back to me in regards to this. I'm using a liquid test kit to test for pH, alkalinity and chlorine but thinking about getting another test kit for CYA and phosphates. Can you recommend a good one?
I got my CYA results from the pool store but I don't want to keep having to go there to test my water especially since it needs regular testing right now.

I just added 2 gallons of liquid chlorine (10%) and tested this morning -- the levels are back up to 3ppm.

The water is clear and I don't see any sign of algae, yet.

Ideally, I would need to drain the water out and replace with fresh water.

Any recommendations on an accurate and complete test kit would be much appreciated.
Thanks

 

[jeffchap]

We recommend either the TF-100 or the K-2006C. Both contain Taylor reagents, just different quantities. The TF-100 is packaged to be most appropriate for residential pools. You can order it at TFtestkits.net.

The important thing is to get a kit that contains a CYA test and a FAS/DPD test for chlorine. Only a FAS/DPD test will measure FC above 10 ppm, which you definitely need for your current CYA level and the FC it will require.