Hi, I am setting up a water-cooled spindle loop but I am a bit confused regarding pump/tubing, I'd appreciate any helpful comments from the experienced.

I am planning on using an Aquastream Ultimate to cool the spindle. Not cheap, but I like the flow and temp alarms, plus it accommodates a small reservoir in the pump itself.
I am more inclined to the radiator/fan setup than the big bucket of water approach. So I am thinking about a 240 radiator with two fans (could add more if necessary, but seems reasonable), the spindle, and the pump.
The loop 4 meters from the pump to the spindle and another 4 meters to come back. The lift is about 1meter. It's a big machine.

The spindle fittings are 8mm push-in.
So I either stick to 8/6mm PUR tubing for the whole loop, which I guess would be the major restriction in the system given the length. Or I use 10/8 directly from the pump to almost the spindle and there I install a couple 10/8 to 8/6 adapters and a short length of 8/6 tubing… not sure if that would make much of a difference.

Sadly the fittings in the spindle have a very odd thread similar to a M10 but I can't figure out the pitch, so I can’t replace them easily. Plus the opening is not that big, so I don’t think I could replace them for a much bigger tubing size anyhow.

So, do you think your Aquastream Ultimate will do the job (considering the length of the loop)?
And would you recommend just 8/6 tubing or the 10/8 + 8/6 combo?

Thanks in advance for any recommendation