One additional thought ( I really insist on this one)
Your choice of Chemical additive may give you problems later down the road.
I have read a few horror stories about wetter water (ask Airspirit, he knows first hand)
Myself used WW on my first system, 6 month later when I went to change my coolant, all my hoses (Tygon) were stained pink
My latest monster is using Swiftech mcp600 Pumps and I went with what Switech Recomends.
It Called HydrX Extreme Duty Coolant.
Pretty sure who ever you are buying the Swiftech pump from should also carry or at least be able to get the recomended coolant from Swiftech.
BTW its a lovely green color
Aardil