How long should a 3" chlorine puck last?

[AB]

Hi, I am using 3" chlorine pucks (trichlor) in a feeder next to the pool pump, to chlorinate my 10,000 gallon pool. Putting one at a time into the feeder.

I am trying to figure out how many days I can go before needing to replace the puck. My levels seem good (3-6 ppm chlorine) for the first 2 days then abruptly drop to zero.

At this point it is too much for the feeder alone to bring the chlorine level back by just adding a puck, so I have to add shock or bleach to get back up to a high chlorine level. I am trying to 'smooth out' the chlorine distribution. Currently setting the feeder level at 2 (0 is closed, 5 is max). If I set it higher it tends to eat the entire puck too quickly and chlorine levels too high.

Does anyone have a rule of thumb for how many days I should be able to use 1 puck, and what I should set the feeder setting on (1-5)?

I would like to get to a point where I replace it every 2 days, every 3 days, whatever, just some kind of a schedule.

Thanks for any help you can provide! Aaron

 

[lightingguy]

an 8oz trichlor puck will have approx 5.5ppm FC for a pool of 10,000 gallons. So it will just depend on how much FC loss you have day to day. This day to day demand may vary a bit based on weather, bather load, leaves, pollen, algae, etc.

If you are replacing every other day that's almost 3ppm a day and perhaps on the high side, but it's going to depend on your pool.

I'm sure a good chunk of the members here use Trichlor because it's so convenient, but most of us who post regularly are in the Bleach crowd.

 

[257WbyMag]

How long the tablet takes to dissolve all depends on how much water is passing over the tablet to erode it away. Tablets will last longer in a floater than they would in a skimmer basket or a tablet feeder.

 

[woodyp]

12 hours in my skimmer basket with the pump runnin' and that sucker is down to a dinner mint.

 

[anonapersona]

When I use my feeder, I load it to the top, I think that is 9 pucks. I usually have it on about 2.0 and they can last the whole week. I know when they are gone by the pH rebound more than anything else.

That said, I only use it for vacations for the most part. 9 pucks will drive my CYA up by 11 ppm and lower pH and TA during that time. Too many vacations and stabilizer levels get too high, things get hard to manage.

 

[AB]

Thanks all, this is some good info. I did not know floaters consume it more slowly than feeders but it makes sense, less water flowing over the pucks.

So should I be filling up the feeder with 7 pucks and setting the flow to a low level eg 1.0, rather than 1 at a time? It seems like my pool could then go for a longer time if I did this.
Thanks again

 

[anonapersona]

When I was following pool store advice, that is what I did, 7 pucks plus a pound of cal-hypo a week. In just a few months stabilizer was well above 100, I think it hit 150 ppm, so hard to read those strips. Could have been higher. By April, 4 months after moving in, I needed to drain the pool to reduce CYA.

About that time I got my TF100 test kit and in just a few weeks was Trouble Free.