IRB can be any color from clear snotty/slimy to black. Wiping the palm of your hand on the sides of the toilet tank from the water line down as you flush the toilet for the slippery etc. is a good test but if you clean the tank frequently or use some type of in the toilet tank cleaner tabs etc. you won't have the build up.
You've said a number of times here that you couldn't get the 3 you sold to work the way you think the system should. Now I see that as you not understanding how the system actually works. I explained why I think you had the problems and you don't like hearing it and now you say I'm belittling you as if you are a victim...
Every one I sold had the knob on it. The regular order version, not the special order version I have mentioned, the knob does nothing but rotate.
On the special order version, the knob is operable and does change the volume of chlorine and you get constant chlorination.
To prove that all you'd have to do is look inside the chlorinator where the internals of the knob are and rotate the knob and see which version's knob does what if anything. Or IIRC, READ THE`INSTRUCTIONS.
I sold and installed a number of them before I started selling them online, I didn't have any I had to service and I taught my customer how to maintain theirs and a few times I got a call with a few questions when the person was going to do the maintenance.
My online customers got a text file of explicit instructions and pictures of how to install and maintain theirs. I rarely got calls with questions of how to do this'er that from internet customers with the chlorinator we are talking about (the regular non special rder one with the non working adjustment knob).
I sold a few of the special order version when it was required. One I recall had a well pumping flow controlled water into a 5,000 gal cistern that then gravity fed to two other 1500 gal cisterns downhill at two other houses on the property and to his studio by the well where there was no cistern. The well was about 500' downhill and 100' below the large cistern by his house. The chlorinator, mixing tank and large Centaur filter was in the well house, each house had a softener and the water from the large cistern to his house was pressurized with a shallow well jet pump and pressure tank.
My equipment replaced older equipment that had replaced other equipment just 5 years before and none worked but what he bought from me. We talked about twice a year for some 4 years or so until I went out of business. He also had a regular version at a 3 family apartment house in town that he owned, he bought that a couple years before the constant version at his house.
I'm done. You will not convince me the dry pellet chlorinator is any better than a solution one. They both have their own problems (even though you will never admit to it). I really don't care about your success stories, everyone has them.
You can continue not selling them or order the right version for your customer's need. Or change your incorrect assumption that they don't work while you don't understand how they work and want them to work how you think they should work; although they don't.
As we see you do not have any success story with the pellet chlorinators.