Last weekend I decided to convert from liquid chlorine to an IntelliChlor generator. While waiting for the device to arrive, I dumped 8 bags of Diamond Crystal water softner salt (99.5% pure) into the pool I shut off my pool cleaner, turned the pump on for 8 hours and went for a swim to get all the salt dissolved. Within 2 hours all the visible salt crystals were dissolved.
The next day I happened to watch the pool as the pump kicked on and I saw all the returns blast brown clouds into the pool. I realized that the brown was previously filtered dust from my DE filter. I completely disassembled the filter and inspected every grid for tears, looked at the manifold for cracks and even looked at the spring tube. Everything looked good. I replaced the o-ring between the manifold and pcv up tube since it was streched, as well as took apart the slide valve and re-lubed it. Unfortunately none of this helped. My next steps are to replace the slide valve o-rings, then the manifold, then the grids.
It seems very suspect that my DE filter has issues immediately after I put salt into the pool. I would not think the salt would affect it. Could the salt cause the plastic or rubber to swell or shrink? I've only owned my house for a year and the DE filter plastic looked brand new when I moved in (Phoenix sun will age plastic like nothing else). Has anyone else seen similar behavior out of a DE filter after adding salt? Perhaps there is some industry experience with converting to a salt pool you all could share.