Dolphin AV-150 pump pressure is lousy

[OblongShrimp]

As I am increasing my number of tanks I broke out my AV-150 again to run some new tanks.  It is currently running 6 HFM filters (4 10gal tanks and 2 15gal tanks).  I tried to hook up 2 40 gallon HFM filters each with 2 outputs and it doesn't seem to have the pressure to run it correctly.  This morning I tried hooking up my AV-50 (currently being used on some other tanks) and it ran the 40 gallon tanks just fine.  I am thinking some of the rubber parts in the AV-150 may be shot (filter is 8 yrs old or so now).  I read that they still sell these parts under AP-100 now and I can get them at kensfish.com.  Does it make sense that the diaphragm or something is just going out on it?  I plan to take it apart to check it out but I just disconnected it and it is way to hot to touch and work on right now.

[35ppt]

I'm not at all familiar with the AV150, but I have replaced the diaphragms on my air pumps. Sometimes rotted, sometimes cracked.

Snap a pic when you crack yours open, I'm always interested to see the inner workings

[Soothing Shrimp]

Diaphragms do wear out.  I'm with 35ppt.  Open the case and snap a pic.