Sand Filter - Alive?

[Poconos]

The filter tank breathing is normal but at 35 psi it's going to expand more than normal. Somewhere on the filter or in its literature should be a max pressure rating. 30-35 psi sounds high and the fact the pressure drops dramatically when you remove the eyeballs says they are severely restricting your flow. Since you really want to continue to use them to direct water flow I'd bore them out as much as you can. If you have access to a drill press it's easy with a cheap drum sanding kit.
Hope this helps.
Al

[larryincanada]

The retuen eyeball holes now are about 3/4" each. Enlarging the return eyeball holes sounds like a great idea! It's so simple and obvious, but completely overlooked by myself.

The only problem is that my pressure-side cleaner works best when the free return eyeball is as small as possible.

I like your suggestion so I will use larger holed eyeballs when I'm not cleaning. My sand filter will be less stressed and it will probably save a bit in electricity at the reduce load.

Thanks!