I'm personally going with this idea with black buckets...
http://hightimes.com/grow/how-to-build-a-two-bucket-dwc-system/
Black and lightproof is a must, many people use any and every color but if the buckets aren't 100% light proof your plants will be battling algae for nutes and if you don't see it; you should look harder because it's not easy to see sometimes as your plants won't necessarily show any signs of problems, but your resis' will have algae in them if they aren't light proof...
Home Depot; believe it or not has the cheapest price I could find on black 5 gallon buckets as I recently been stocking up on them....but online or otherwise... any and all other colors aside from the orange Home Depot buckets were the same price or more I believe... but black is the way to go don't believe otherwise, the blue lowes buckets are close but if you press a flashlight up to the outside of a bucket and you can see it on the inside; vaguely or otherwise; it's not light proof... anything that's not light proof is going to breed algae... and that is a fact... if as I said u put a flashlight up to it and u see anything; it either needs to be covered with light proof insulation or painted... more work than necessary, the black ones are more expensive in most places because they know why we buy them (because we're growing weed in them and you should be using black/light proof buckets to do so) but time is also worth $... if u wanna save a few $'s on a cheaper bucket, you're gonna spend it on paint or something to make it lightproof, save the time n buy black ones..
Edit:
in that link to HT; they list a 1-3/8" hole saw for the 1.5" uniseals; (that's the id of the pipe not od) but a 2.5" is required for that size uniseal/pipe and the pipe is not called black pvc when you buy it, it's called abs, which coincidentally needs to be used because pvc isn't 100% lightproof if you need more of a reason to use black buckets, however a short piece of pvc pipe is easily covered with the aluminum foil type tape...