Time to change sand?

We are novice pool people. We purchased this pool used a few years ago. It is a super splash pool (10,000 galloons)

Our pool filter is a 18" Meteor Sand Filter. My husband calls it the ORB.

It usually runs at 21 pbi and we would get a nice outflow of return water...the force of a water coming out of a bath spout.

This year the pump starts at that and then slows down to a weaker force and it is running at about a 28 pbi. We are getting suction but it appears that it is not as strong. We have backwashed, rinsed and cleaned out the basket in the skimmer and by the pump. We even opened up the pump and cleaned that out.

Do you think we need to replace sand at this point? The sand that is in there is at least 5-6 years old.
Also, we are just opening the pool and started all of the chemical process so we need to keep the pump going...is this harming it?

Any help is appreciated.

Also I do have bubbles in my pump filter.

It would be a good idea to check the sand - it could be gummed up. Might want to look at the parts page here:
http://www.pentairpool.com/pool-pro/...lters-112.htm#
first so you have an idea what's inside.

Is it safe to continue to run the pump....are we hurting anything by running it?