Can't you pivot the AC intake tubes to reduce flow? It's been a while since I've had one, and it was a 10, not a 70, but if you rotate the tube (after the U joint, inside the box away from the pump housing, it would reduce the flow.
Also, it may not be a bad idea to swap the check valve for a new one, just to see if that's the problem. They're not super expensive, and it's probably not a bad idea to have one hanging around anyway.
My DI filter housing is completely full. Are you positive that you have the inlets/outlets "wired" in the correct fashion? Is the water pressure in your house exceptionally high?
Large green rhodactis (attached to rubble) - $10 sold etannert Candy apple paly (2-3 polyps per plug) -$5 1 pending to theresa (1 left) Undata (green w/light blue polyps) -$10 (1) Fairy Dust Palys (what these were sold to me as, not so sure they match the pics online) (20-30 polyps) - $30 Fire and Ice Zoas (10-15 heads) $25 (pending to theresa) Large devil's Hand (fist sized with attached LR) with blue clove polyps on base ($5) (2 of the three large lobes are pissed because I just moved it) Blue clove polyps ($5 per) Here's the blue clove polyps: