I did a new mod to my Pan World 100PX-X today. The original fan that I had on broke, the cord got pulled and broke so the pump has been running for about two months with nothing and was so hot that you couldn't touch it for more than a couple of seconds.
Here are some pictures of the new mod.
Here are the materials. About $15 worth. Fan for $10, Stainless steel bolts and nuts for $5 and I already had the 4" PVC coupling and the zip ties.
Here is the fan. 21dB, 78 CFM, 380 mA, but I am running on a 200 mA transformer. So it running a bit slower and quite a bit quieter.
I drilled two holes for each of four zip ties to hold the fan on and three holes for the bolts to hold the assembly onto the pump. Here is the picture of tapping the holes.
Here is the finished product. I used some black netting covering for the wires. Looks a bit better. I used lock nuts to make sure the bolts don't vibrate loose.
And installed

I installed the new fan mod without removing the pump. Heck I didn't even shut off the pump. I don't know about temperature decrease, but the pump is cool to the touch now.
Thanks to dandy7200 for the mod idea.
Keith