Old Pucks and Color Match Tests

[APoolFanCT]

I’m wondering... what happens to old trichlor pucks? What do they break down to?

This is my first post. A couple years ago I was doing all pucks and had no problems. Crystal clear pool. I added about 3 pucks a week in my offline chlorinator. I only tested Chlorine and PH with a simple 5-way color match test from amazon. Never had problems. Vacuumed once a week.

Then I found your site. My CYA was over 250 but the pool was clear and the color test said my chlorine was 1-3ppm (Question - how is this possible? The DPD drop test said chlorine was more like 15ppm. Does the color match test implicitly control for CYA?)

I had a salt cell installed and ditched the pucks. Over a couple years of partial drain and fill for winter, the cya has come down to a better level - 60ish. When I opened this year I decided to toss in some old pucks I had to add chlorine and stabilizer while I picked up some salt, just to use them up. I kept the salt cell off. Well, I checked the chlorine yesterday and it was 0.5ppm. What’s going on? Are my pucks dead? I keep them in sealed bags in a vented bucket in my pool box. They probably get hot in the summer and are 2-3 years old. But they still smell like chlorine. Are they adding any chlorine or stabilizer at this point?

Anyway I shocked with cal hypo to get my FC back up and all is well, but mostly just confused by what’s going on.

FC: 6
PH: 7.6
TA: 75
CH: 100 (vinyl liner)
CYA: 60
SALT: 3600
Borates: 20

 

[IceShadow]

Pucks won't break down and can be stored forever as long as they're dry. They're certainly not instant, and if your water is cold (assuming so in CT), it can take even longer to dissolve.

How does the water look?

 

[APoolFanCT]

Pucks won't break down and can be stored forever as long as they're dry. They're certainly not instant, and if your water is cold (assuming so in CT), it can take even longer to dissolve.

How does the water look?

Crystal clear. I have the heater on so water is 80 and the chlorinator full of pucks. In years past that’s been plenty to keep up FC. I know there are a lot of confounding variables. Could just be the birch pollen raining down.

 

[IceShadow]

It could be - your CYA is getting pretty high, though, at 60. Pucks do add CYA. What test kit are you using? If you could, it would be good to fill out your signature with your pool size/surface/equipment/testing kit, so that we can help you better.

Also, forgot to say it - welcome to the forums!

 

[APoolFanCT]

Thanks!! I will fill it out. I use the recommended Taylor k2006 kit. Since I have a SWG I’m targeting 70 for CYA. My last tablets are half dissolved at this point after 3 days or so; when they’re gone I’ll turn the generator back on (I’ve read bad things about using both simultaneously). I figured - a little extra chlorine, cya, and acid (so I can add borax) - why not use my last 5 pucks?