This is my automatic pool chlorinator. I decided I wanted an automatic pool chlorinator, and I did not want one floating in the pool because of my grandkids being so close to the chemicals. I also didn't want to pay $60+ for one made by a manufacturer, and I made this one for under $30. I will give you the basic idea on how I constructed it. There are probably other ways on how to construct one. The basic principle runs off of pressure differential. The high pressure coming off the pump the low pressure side goes into the outlet of the pool filter.

Supplies

Culligan HD 950 water filter housing. ($10 Facebook marketplace).
Hose clamp kit from Amazon $16.
The rest of the parts I had on hand.
2- 1" male threaded to slip PVC connectors.
2- PVC 1in to 1/2in female threaded adapter.
2- brass fitting reducers 1/2" male to 1/4" female.
2- 1/4" male to 1/4" barbed brass fitting.
2- small hose clamps 1/4"
2- 6 in shelf brackets and miscellaneous screws to attach to the wall and the housing.

Step 1: Main Assembly

I started bye basically stacking all the fittings. Then threaded them into the lid of the filter housing. I used Teflon tape on all male threads. I ended up using quarter inch barbed fittings, instead of the fitting supplied in the clamp kit because of the thread sizes. I didn't have anything that matched.
I then use screws and anchors to attach the brackets to the wall and to the chlorinator housing.

Step 2: Water Line Connections

I use a cordless drill ,3/8 drill bit, and a screwdriver. I first had to decide where I wanted to install them. I figured it'd be best to install them on rigid PVC, not flexible. That's why the high pressure clamps and fittings are on the elbow.
I started by assembling the fitting into the clamp and the rubber gasket on to the bottom of the fitting. Drill the hole into the PVC elbow. Then placed the clamp/fitting assembly over the hole and tightened it down. I repeated the same steps on the pool filters outlet PVC line. I then measured how much waterline I would need from the chlorinator housing to each of the clamp fitting assemblies. on the chlorinator housing I simply used small hose clamps. On each of the hose clamp fitting assemblies I used the supplied compression fitting nut.

Step 3: Adding Chlorine Tablets

To install the tablets in the housing, simply unscrew the bottom of the chlorinator housing, I put in five 3" chlorine tablets where the filter would have normally gone. Sprayed the o-ring with a silicon lubricant (do not use a petroleum-based lubricant it tends to make the o-rings swell and you'll have a hard time getting it back off). Reinstalled the bottom on to the housing. Turn on pump

Step 4: Future Upgrade

In the future I plan to add a one-way check valve to the input side of the chlorinator. This way highly concentrated chlorinated water won't back up into the pool pump. I may also add a adjustable valve on the output side to regulate the amount of chlorine going into the pool if needed. I have now been running the chlorinator for a few weeks and my chlorine levels are perfect. I added the pic for an examples of check valves and for adjustment valves.