I've built several of the wier box type (albiet I've made some madifications/improvements to the ones Marc L. has plans for) they work quite well. One advantage over the U tube type is they can be drilled and an 'aqualifter' pump used to draw any air out of the box before it can accumilate and break the siphon. Actually have a monster on our 180 right now that can easily handle 2K+ gph.

They are pretty easilly constructed with some basic tools. If you want to go this route let me kow and I'll draw up and post some of my suggeted mods to them.

I suppose you could do that with a U tube though the material used for most U tubes is generally pretty thin and may be more prone to cracking if drilled because the material is stretched out to make the bend.

IMO CPR gets bashed for the price tags their products carry.... charging over $100+ for something that can be constructed in about a hours time with $15 worth of acrylic is outrageous.