Quote:
Originally posted by bigben2k
Ok, but if you knew that you were going to have a good pump, like that Johnson pump (or two  ), what would you do different, if anything?
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I have an Iwaki MD-30RZ here that I test with, along with an Eheim 1048, and Eheim 1250.
I can achieve 3lpm, 4lpm, 5lpm, 7lpm, 11lpm and 12lpm flow rates by hooking the pumps up in series or alone, and/or by turning one of a pump in series off (which artificially adds restriction).
For the Rev 1 block, the performance difference between 3lpm and 12lpm, after factoring out the difference in water temperatures, is close to 2.0C on a ~80W heat load.
I expect the difference to be slightly less with Rev 2 because of what I talked about above.
I wouldn't do anything different. In my mind, density of the jets is more important that maximising each single jet for the strongest possible pump. Get the density up high enough and the block will still benefit from a high pressure pump while losing less on the lower pressure pumps.
Basically the goal here is to get the flow vs C/W curve as flat as possible, but be starting off at a much lower point at low flow rates than other blocks.
Look at the flow vs C/W of the WW vs the Atlantis (an impingement block) for an example of what I mean. Above 2lpm the Atlantis benefits from an ever increasing flow rate, moreso comparatively speaking than the White Water. From 2lpm to 10lpm the Atlantis picks up 0.05C/W, while the White Water picks up 0.03C/W, but the White Water starts off so much lower. In the end the WW is miles in front, despite gaining less from higher flow rates.
I think that best highlights my thinking on this. Yes, the gains may be somewhat limited when contained as opposed to a more open impingement approach, but we're starting off with the curve so much lower that by the time the upper-end gains come into play, we're still ahead.
Tune for the low-end, and the high-end performance follows. It's important to keep one eye on the absolute performance and not let relative performance differences of different approaches overshadow the absolute number.