Laing d5 vario pump.

Hi everyone here.
I hope this is the right place to post this.

Firstly i have an i7 platform on a ASUS p6t delex v2 mobo and 6 gig ddr3 1600 ocz ram with a ocd 280 gtx. The sustem is ocd to 200 bclk and stable with the cpu at 4.2 gig. My water cooling rig is an aquaduct 720 mk3 from Aquacomputers but i have slightly altered it to use 2x tripple 120 fan double pass tripple thickness rads and cooling only the NB and cpu i can keep the cpu to just under 60C under prime or OCcTpT.

Any way to my question. ..... I am about to design and build an external water cooling system that I hope will cope with an oc system as well as at least one preferably 2 water cooled GFX cards, but for this i need a high flow pump that is also not too noisey. As well as that I want the pump speed to be ajustable easily so that the system can slow down for either when the system is not under load or for systems with fewer cooling blocks in the loop.

What i want to know is the flow rates for the laing d5 vario pump in ltrs per hour on the 5 different settings at 12volts.
So can any one pass on this info to me. I have seen the charts that Laing provide but those charts all take into acount having a head of water. But my system will be a closed loop wil the return back to the reservoir submerged so gravity will not play a part in the system.
I am looking for a pump that can be reduced to around 50 ltrs per hour but also manage over 150 ltr per hour when needed. I am aware that the d5 pump is suposed to make some 12 to 1500 ltrs per hour on speed 5 but not weather this is acurate or what sort of flow to expect on the lower settings.
the system will rin 10 mm id piping.

any first hand info on this pump would b much apreciated...