Don't most people paint their tube black anyways to avoid algae?
I was thinking the same exact thing as soon as I read the clear tube comment. I couldn't tell you how many times I've seen somebody say to not use a clear hose. Clear hoses allow light through, which then lets algea grow. I've seen some pretty nasty tubes...
The main problem found with any syphon type overflow box is the U pipe loosing its syphon,this is due to the air bubble build up,the reason a lot of people are moaning about them is because they cant see any bubbles because they've painted them,You need to see through them.I've had mine for well over a year and have no algae whatso ever,again this problem occurs from a bad setup of flow through it and direct sunlight,a piece of dark plastic over it would suffice if you realy wanted to keep any sunlight out and you can easily check it.
just use the green ehiem tubing.The U-tube would be fine clear (i would believe). The tubes we are talking about is to and from the sump. Considering most people have some sort of light for a refugium or for visibility under the stand, algea would grow if it was clear.
According to the link you posted a 3" pipe does 5500gph not 600
I use an eshopps 800 which handles 800gph with a 1" pipe
I use this site for pipe size/flow rates
GPM/GPH Flow based on PVC Pipe Size, ie, How much water can flow through Sch 40 Pvc Pipe Size 1/2" 3/4" 1" 1.5" 2" 2.5" 3" 4" 6"