What constitutes "specialist coolant"... anything with corrosion inhibitors? I was under the impression that using automotive fluids (like anti-freeze) in a loop was harmful to plastic parts inside a pump. Im wondering if something like Feser Base would suffice. I have some copper radiators on-hand that Id like to use but mixing metals just sounds like it's asking for trouble.
Any coolant designed for 'PC' watercooling will be fine. Plenty of barbs and tubing, you won't need more.