Coolant: I'm not sure which EK coolant you mean but I believe some of them are made by Mayhems. Mayhems coolants are generally supposed to be good - I say "supposed" as I have never used them and I know there is some controversy currently.
Personally I would go for clear - and this is a personal thing. Mainly if it's colourless you aren't going to be massively irritated if you spill it on the carpet but also it's definitely not going to stain your tubing pink/purple/alien green so won't be a problem if you want to go coloured once you've got everything worked out. Other people love their pastels etc but I've always worried it'll settle out or bung up somewhere and I know that realistically I'm not going to be draining, cleaning and refilling every six months....more like two years when I have to upgrade something anyway.
Tubing: About the only thing in stock at OCUK is the Primochill and that appears to be what's at the heart of the Mayhems issue. If you want to go Mayhems coolant it may be worth staying away from Primochill tubing or anything PVC based which I think would rule out XSPC too. Have a look at this current
thread and see what you think.
For what it's worth, I use
EC6 Clear and Tygon E3603 tubing in 3/8 ID which is 12.7/9.5mm which is near enough 13/10 and works with the 13/10 EK, Alphacool and Koolance fittings in my rig. I know this combination works but I also know that Tygon isn't available from OCUK and is about £7/metre.
I like to have my tubing and my blocks clear so that I can see if something is gunking them up....but that's a trade off against style you might not want to make.
Stop: Something like
this obviously adjusting style or colour to taste. Just means that if the tap is turned accidentally, or it leaks, the stop seals the end. When you want to drain, you take the stop off and then open the tap. Utterly unnecessary....until
stuff happens.
Y-fitting: If you look they are all G1/4 female threaded and so are the taps. Cheapest is out of stock but something like
this So you either need to treat the Y-piece as a device (like CPU) and buy four extra fittings (one for each 'arm' and one for the tap) or you can use something like
this to connect Y to tap and even Y to rad.
You could alternatively use one of
these cube-style T-pieces to connect onto the rad and then fittings off each side onto CPU and tap. Or tap on the male part and rad to pump on the 'through' connections.
You say "Central fitting" and I'm not sure what you mean. Do you mean straight fitting? If so, straight fittings are fine provided your tubing doesn't go round too sharp a corner. You used to get 90° compression fittings but these days the fashion seems to be to have a 90° bend and then put the compression fitting of your choice on the end. This helps if you have to turn a sharp corner. Something like
this with one of
these screwed onto it.
Hope that's of some help. Difficult to recommend specifics when all the fittings always seem to be out of stock.
