Filter PSI rises shortly after opening

[Burm1000]

OK, bought house with above ground pool late last summer, pool in disrepair, so I paid for pool school with local company. I opened pool today...but couldn't find notes from pool school, but thought it was pretty straight forward.

1. Set up filter
2. Added sand (protected tube in middle so no sand would go in)
3. Set up pump hoses
4. Turned it on

All seemed well for 10-15 minutes, went to check on kids, came back a few minutes later and PSI was jumping all over the place. Figured to many leaves so I cleaned both baskets (one at pool and one in the pump). Turned it back on. No luck. Kept acting erract. Finally settled at 25 PSI and obviously not doing any good there. It started around 12 PSI. I did not backflush as I'm concerned I did something wrong. It was only on for < 45 minutes. Should go about a week even when opening...right? Thoughts.

 

[Bama Rambler]

The first day opening can overload a filter very quickly. I'd go ahead and backwash and see how the water coming out looks.
If you can provide us with a list of your equipment and even some pictures will help we can give you better advice.
How did the water look prior to turning on the pump?