BillA
Looks like we were typing and posting at the same time.
Okay, I think I see.
If we are going to use an aquarium pump then it's got to be low resistance high flow with larger channels and physically induced turbulence - al la "turbulators" say.
If we use a small, low volume, high pressure pump then the block should be low flow small channel as in the cross-drilled block say. But it would probably only need say three layers of tubes though, or would it need more (as in the recent block under discussion)?
By the way Bill, were the TIM's of any use??
Can O' Beans and mr. phantastik
How about those self drilling self tapping sheet metal screws, I'd think they would cut a nice coarse thread into a hole in a copper block. Also, how about those concrete screws that will go directly into concrete, they're pretty damed tough and should be able to form a thread in copper easily.