The equipment you have listed will make your tank octo-escapable. The blue ring octopus has a beak that is like 1/4" if I remember correctly, and an octopus can squish out any opening that is smaller than its beak. That includes going up the output of the Prizm. You need to cover the top of the tank
in its entirety, and they are much stronger than they look, so they can push the top off.
Are you aware that Octos are very short-lived? Are you aware that blue rings only show their blue rings when they are startled, irritated, or stressed? They normally just look like a brown blob, and really aren't overly exciting. Why not try a different type of octo?
Do you have any pets or kids or other people living with you that could be affected? If it escapes a nosy cat or dog or kid could easily get bitten checking it out on the floor.
sphelps has a red octopus right now, and although he hasn't had it very long he may be able to provide some insight for you.
I agree 100%, especially the bolded part.
My thoughts exactly.
EDIT:
untamed posted pretty much the same thing as me at the same time. Is there an echo in here?