Freshwater pool chlorine tablets showing falsely high chlorine

[sean.a.tull]

Bottom line up front : what can cause a freshwater pool to slow falsey high free chlorine readings?

I’ve had my 14k gallon in ground pool for about 4 years now. It has an automatic chlorine feeder.

For the last 6 to 9 months I've had this issue where my chlorine is constantly showing higher than it must be.

1x 3 inch chlorine tablet per week (and 0 liquid) is giving me 7-10ppm free and 0 combined chlorine With the k2006 dpd test. Cya is about 80 right now. Pool is in Orlando Florida on north side of home so it's partly shaded with a pool enclosure.

Ive even gone a week adding no chlorine and still the chlorine reading will show high. I don't think it's the way I'm resting because pool store will show about the same results. I also don't believe the chlorine is really that high because I had algae and water mold form.

 

[chazas]

Bottom line up front : what can cause a freshwater pool to slow falsey high free chlorine readings?

I’ve had my 14k gallon in ground pool for about 4 years now. It has an automatic chlorine feeder.

For the last 6 to 9 months I've had this issue where my chlorine is constantly showing higher than it must be.

1x 3 inch chlorine tablet per week (and 0 liquid) is giving me 7-10ppm free and 0 combined chlorine With the k2006 dpd test. Cya is about 80 right now. Pool is in Orlando Florida on north side of home so it's partly shaded with a pool enclosure.

Ive even gone a week adding no chlorine and still the chlorine reading will show high. I don't think it's the way I'm resting because pool store will show about the same results. I also don't believe the chlorine is really that high because I had algae and water mold form.

CYA too high. Chlorine test is probably right

 

[PoolStored]

Welcome to TFP!!!

For the last 6 to 9 months I've had this issue where my chlorine is constantly showing higher than it must be.

Not sure what this means? If you are getting high readings and YOU think it should be lower, it might be the age of your reagents. How old are they? If they are old and have degraded, they will require more drops to measure the same FC...resulting in higher than expected results.

1x 3 inch chlorine tablet per week (and 0 liquid) is giving me 7-10ppm free and 0 combined chlorine With the k2006 dpd test. Cya is about 80 right now. Pool is in Orlando Florida on north side of home so it's partly shaded with a pool enclosure.

CYA about 80, I would suspend the use of pucks and use liquid chlorine. At level much above 80, it is difficult to maintain enough FC to sanitize the pool. The pucks add CYA, and the only way to reduce CYA is by draining water. The good news is that CYA will degrade over time, so if you stop the pucks now, CYA will come down.

Always chlorinate and keep FC based on your CYA. Link->FC/CYA Levels

 

[sean.a.tull]

Could 1 tablet a week really be producing chlorine levels as high as I'm getting?

 

[PoolStored]

No, one puck in your pool would add 4ppm of FC.

My guess is that your are under chlorinating and your reagents are old. How old are they?