Pressure keeps rising on my EC75A Hayward perflex. We have back flushed also tried taking the filter apart and soaking it. The pressure rises within 24 hours and suggestions

SOURCE: No pressure at all on pump gauge

Without knowing your pip and valve layout, it is difficult to assess the stiuation, but it sounds to me as if either a valve that lets the water into the filter is shut, or the filter is full of air and needs to be primed. On some models if you loosen the top ring until the water fills the chamber and starts to overflow that takes care of the problem. But if you cannot tell by looking at the layou if a valve that should be open is closed, or don't know how to prime it, don't run the pump until they can come back.

SOURCE: Hayward eC-40 pump losing pressure very fast

A better way to clean the filter tubes in the EC40 is to remove the filter tube assembly and soak it in a 5 gallon paint pail that is filled with a solution of water and a 20% muriatic acid, available at hardware and home center stores. Be very careful handling the muriatic acid. Don't splash it around.

Mix it in a 1-to-1 ratio with water and soak the assembly for at least 8 hours. Keep the soaking pail out of the reach of kids and animals.

Remove the assembly, properly dispose of the acid mix and refill the pail with clean water. Soak again for 3 to 4 hours, then reassemble your filter.

Some pool guys say it isn't necessary to soak the tubes in clean water because the muriatic acid will not harm the pool water and will reduce the pH if it's too high. I've always soaked them to be safe.

This is a link to the Hayward manual that describes the process:
www.haywardnet.com/products/Manuals/pdfs/manual9.pdf

SOURCE: Do I need a new sand filter psi gauge?

It wouldn't hurt to replace the gauge every few years, since it makes contact with heavily chlorinated water. They are available for less than $10.

SOURCE: I bought a used Hayward Perflex Extended Cycle DE

Here is a link to the hayward manual. Be sure to follow the pre-coating insturctions carefully.
Use only the swimming pool grades of
diatomite, such as:
CELATOM . . . . . . . . . . . Eagle-Picher Industries, Inc.
AQUA-CEL . . . . . . . . . . Johns-Manville Products Corporation
DICALITE 4200 . . . . . . . Grefco, Inc.
WITCO . . . . . . . . . . . . . Witco Corporation
The EC-50 filter uses a 5 lb. (2.3 kgs.) charge of diatomite (D.E.)

Here is a link to the hayward manual for a EC-50 I think its almost the same as the EC-45
http://www.haywardnet.com/products/manuals/pdfs/manual10.pdf