Filter doesn't let water through

[Disvet2]

Our Sequel II DE filter won't let water through after 3 to 4 hours. We just opened our pool and cleaned it, backwashed the filter, added new DE and turned it back on. After 3 to 4 hours there is just a trickle of water returning to the pool. If I turn off the pump and open the backwash line and move the handle to Backwash for a couple of seconds and turn back to filter, put the backwash line cover back on and turn the pump back on I get a huge rush of air and water pushed through into the pool and then we have real high water flow for a couple of hours and have to open to backwash again as described above. What will cause this? It seems that a "vapor block" is developing in the filter which slows water flow to a trickle until I do the backwash steps described above. Thoughts or solutions anyone?

[Teapot]

It's doing its job, you may not like it but DE clogs easily because it filters finely. As your water gets clearer this will happen less.
When you get bored of the mess, the money spent and all the additional time, switch to a sand filter with Dr Dryden's Activate glass media, it's fitted for life and filters almost as finely as DE, you can also use flocculant and then it will filter finer than DE but cleans with a simple backwash.