This is why I like these, I can do the final rinse with just an open hose from the vessel and even in cooking July sun I can simply walk away.
The hard water here is insane, so nasty.
You can tell when the resin needs changing as you start getting very small easy to remove spots...that's my signal.
I have an electronic TDS water tester, tap water here is about 260 PPM, and when you put fresh resin into the vessel it goes to 0 parts per million.
I only really use it in the warmer months.
I would never run this vessel in line on it's way to my Kranzle, if anything went wrong and the resin beads got into the Kranzle then that could be a very bad day. So I just put the end on the garden hose into it, then a 10 metre length of hose to rinse with.
The TDS meter was also handy when I re-gassed my A/C in the Passat, it's also a thermometer I could hold in front of the vents
Resin vessels are used for the deionisation and purification of water. This resin vessel has a capacity of 11.0 litres, and used in conjunction with DI resin can produce top quality water which is suitable for any pure water application, including pole window cleaning, aquatics, drinking water...
www.mycarcleaning.co.uk
Amazon product
View: https://www.amazon.co.uk/TDS-Meter-Digital-Water-Tester/dp/B0BBSW45P3