Pucks

[PoolGate]

Good Lord how long does it take for these frickin' pucks to dissolve anyway? I thought I'd put a few in to help chlorine get up and add a bit of cya while waiting for it to warm enough to turn on the SWG. Well SWG is now on and I added cya and these pucks after a week are barely starting to dissolve!! I took them out and tossed them. Sheesh!

 

[Arizonarob]

Maybe you bought “urinal cakes” instead of chlorine pucks?

 

[Rancho Cost-a-Lotta]

Maybe you bought “urinal cakes” instead of chlorine pucks?

Same thing.

 

[Arizonarob]

Your pool must smell lovely then!!

 

[an1vrsy]

What I've discovered with those blasted pucks that with variable speed pumps there isn't enough water flow to dissolve them. I noticed in your signature you had a variable speed pump.

I went on a 7 day vacation and when I came back the pucks had hardly changed appearance. I used tongs to get them out. After they dried, I weighed them, if memory serves me, I put 3 pucks in at 21 oz and they weighed a little more than 18 oz after a week.

When I had a single speed pump, 1 puck would have completely dissolved in a week, so 7 oz easy. It wasn't me that figured this out but another thread related to this subject and then it finally dawned on me it wasn't enough water flow or strong enough...

 

[TFP_Addict]

I don't mean to high-jack this thread. But How much cya gets released per puck?

 

[QueHales]

According to my experience, each 3" tablet weighs in the 7 to 7.5 ounce range. So rule of thumb, about a half pound. They are around 55% by weight cyanuric acid, so you are adding roughly a quarter pound of CyA per tab. In a floater, we see them last about 9 to 11 days to dissolve. The time length with active water flow, such as when you put one in a positive-flow erosion-type feeder, varies depending on flow rate.

 

[mknauss]

I don't mean to high-jack this thread. But How much cya gets released per puck?

10 ppm FC from Trichlor raises Cyanuric Acid (CYA) by 6 ppm.

 

[HeyEng]

10 ppm FC from Trichlor raises Cyanuric Acid (CYA) by 6 ppm.

Wow, that is significant! It wouldn't take very long to get the CYA up to 100+ with that concentration.

 

[Richard320]

If you look at the bottom of PoolMath where it says Effects of Adding Chemicals, you can see exactly how much CYA you'll add via trichlor, assuming you input the correct volume up top.

 

[TFP_Addict]

I don't understand why there isn't a more accurate test for CYA other than what we currently have now. It seems like so much rides on CYA.

Another question: What is the storage life of Pucks? Do they degrade over time?

 

[setsailsoon]

I don't understand why there isn't a more accurate test for CYA other than what we currently have now. It seems like so much rides on CYA.

Another question: What is the storage life of Pucks? Do they degrade over time?

Don't know the maximum life and that depends a lot on how they're stored. Right before I switched to TFP method I had purchased a large bucket of 3". After switching to TFP I only used a few when out of town so the bucket lasted a little over 3 years and the last few were still perfectly shaped and worked as expected. Pucks were stored in the original container that was in a deck box outside. So it stayed very dry. Now that I've switched to SWG I'll be testing much longer storage times for my remaining pucks.

Chris

 

[ManiacalMama]

So at that rate, would it make sense to throw a 3" puck in a floater each month to replenish CYA loss? Since last summer I've nearly lost all my CYA because I wasn't thinking about it and keeping up with it.

 

[mknauss]

You can. I use them when I go out of town (even with the SWCG) as they are acidic and keep the pH and TA in check. You can usually expect about 5-10% loss of CYA each month during June through August due to elevated water temperatures.

 

[ManiacalMama]

I think I was about 40 cya in August last year. I just ran a test a couple days ago and got a zero reading. Although I realized after I added about 20 ppm cya that I should have let the water come up to room temp before I tested it. I'm going to test it again in the next couple of days and adjust as needed. I guess I can just add a little of the powder each month too, I just don't want to bother with the sock every time.

Pool math says I need to add about 9.5 oz to add 5ppm cya, would I need to bother with a sock for that little amount, or could I just broadcast it?

 

[mknauss]

You can carefully add it straight into the skimmer if you like. Make sure it goes in slowly and break up any clumps. Just plan to test for it after 5-7 days.

Or use a puck or two.

 

[ManiacalMama]

Thanks!