[Gooserider]

Good discussion sevisehda, your examples make sense, and look like reasonable real world numbers. I suspect (can't prove yet) that I'll be able to get higher flows than your example, but I think your reasoning still holds.

Pump - I'm currently planning on a Danner PondMag 3. It is smaller and less expensive than an Eheim 1250, and has better flow rate and head numbers if one is to believe the advertisements. I've searched the forums here, and haven't found anything really bad said about it.

Blocks - I'm going to make my own, but I'm planning to go for a very high flow design (at least as I understand how to get high flows) to get good cooling via 'brute force' of lots of volume, rather than fancy flow juggling tricks (like Cathar & Co.)

Rad - From the reviews I've read, discussions, etc. I've gathered the impression that most of the WC purpose designed rads have pretty high restrictions, and tend to be on the small side. I'm planning to use a heater core (supposedly less restrictive) big enough to put at least 2 92mm fans side by side blowing through it. I've just ordered an AMS CK1100B 20 bay cube case from Servercase.com, (195.00 w/o PSU) and figure on hanging the rad off the back of the case which I'll mod to have the two case exhaust fans blowing through it.

I'm thinking now that testing for comparative flow volumes with the hardware I'm actually using will be my only way of knowing for sure what will work best, and that will have to wait a while until I get it in hand.

Gooserider