Hello I put in a brand new Zeolite filter and for 2 agonizing years the water was cloudy, I read hundreds of blogs on various sites trying to find the answer and I think it was from one of the blogs on this site that I finally solved my problem.
I backwashed thousands of litres of water down the drain over those two years and it did me no good, the problem was so simple, the zeolite is light and when you first put it in some of it will inevitably float up and may wedge between the gasket and the plate of the multiport valve (when you push down on it to operate it).
It just takes one pebble sized piece of zeolite to do this and the filter is rendered completely ineffective. Every bit of dust you suck up from the pool will just find this gap and bypass the filter completely and go back into the pool.
I undid all the screws around the valve, opened it up and cleaned it out, after only a few days the pool was shimmering like the hope diamond!
I hope no one has to suffer this problem as long as I did, after two years of using it I hated Zeolite, but now that its working I think it is a great filter medium, seems as good as my old diamatatious earth one was, I am glad I didn't give up because I was thinking of ditching the zeolite and putting sand in, but I think zeolite is actually a lot better than sand.