The sin of threading a Stenner line into a puck holder


Bronze Supporter
Apr 25, 2017
St. Louis, MO
Hi folks--

I have a pool--my first--for which construction will probably be finished in a week or two. I've pretty much decided to build myself a liquid chlorine pump system, but I didn't settle on this until after the plumbing and equipment were complete.

Reading through old Stenner threads, I see that the practice of threading the injection line into a 1/2" port of a chlorine puck holder is roundly discouraged... but I'm not really clear why. People say, reasonably enough, "don't mix chemicals." But what, more specifically, would be the risk of injecting bleach into a tank holding a solid chlorine puck? Something terribly exothermic? Something that generates gas? What's the realistic worst-case if somebody screws up?

The above-ground PVC plumbing in my system is pretty compact, and I'll have to dig stuff up if I want to have enough slack in the lines to insert a tee to mount an injection port properly. So I'm tempted to just jack the Stenner line into my puck holder for the first season, to make sure that I'm satisfied with this setup as a permanent solution. Still, I won't do this if I have some more concrete idea of what bad outcome I'm avoiding.



TFP Expert
Apr 29, 2016
Quaker Hill, CT
I forgot exactly what the reaction was but you got it. There is potential for a serious and damaging reaction if you mix liquid chlorine with pucks. Even the left over chunks of a puck are enough to cause a problem. They are two things you really don't want to chance mixing on accident say if somebody comes along who doesn't know the pool ( like you sell your house, or go on vacation and ask somebody to watch your pool) and adds pucks to the feeder then turn on the chlorine pump.

Are there any tee or 90 fittings in your return line exposed? The double thickness of PVC in those areas will allow you to thread and tap an 1/8 or 1/4 inch NPT fitting right into the line without having to cut and re-glue anything.

Another option is to remove the inline feeder (you aren't going to use it anymore right?) and put your injection port there.


Mod Squad
LifeTime Supporter
Jul 10, 2012
Tallahassee, FL
It is the danger of the toxic is bad stuff. Our biggest worry when people say "but I won't put a puck/tablet in the tube" is that SOMEONE else might. It is a very dangerous thing to even take a chance on.



Bronze Supporter
Jun 3, 2015
Missouri City, TX
I don't know what puck holder you have, but I was able to unscrew the tower part of my Pentair Rainbow, leaving the diverter tee in place - and made an adapter to go where the tower was. Adapter was made up of a 1.5" threaded coupling and 1.5"x0.5" reducer bushing.


Bronze Supporter
Apr 25, 2017
St. Louis, MO
There's an elbow that I could potentially tap into, and I've got a tap set collecting dust in my basement, but I'm somewhat worried about whether the result would be reliably water-tight. I'm good with solvent-welding but haven't done a lot of tapping into lines.

I'll have to look more carefully about whether the solid chlorine holder is removable. I'll try to post a picture this evening...


Well-known member
Aug 19, 2015
SW Ohio
Our stenner is threaded into the puck holder.

Puck holder was installed by pb and right after I discovered this forum. We never used tablets and never plan to so with them not even being in our household theres no chance the two will ever get mixed. If for some reason we ever sell the house then we'll deal with moving it so nothing happens under new ownership.