Buildling a 40 site RDWC system and cant decide if 2" pvc is large enough or if i should plan on using 3". Current Cultures double barrel 32 site says it uses 2" unijoints but the pictures just dont look like 2 inch pipes. Is 3" too large? Obviously pump will be adjusted accordingly.
I would agree. I don't ever plan on having a 40 plant setup, but I feel in most situations, go with more than you need. It doesn't hurt to do so anyway, where to little can cause issues.
I design systems for dispensary warehouse grows, and I'm constantly breaking big systems that don't work for a variety of reasons down into smaller ones that do. That advice is worth ten grand to the last outfit I spoke to. Twenty is an outside maximum, my preference is twelve. I do not truck with undercurrent; too expensive and they make you pay extra for stuff that isn't. You wanna go big? The new buzzwords are 'modular' and cellular'. Why? 'IPM'.
I run 2" with no problems for the last few years. I am not running "undercurrent" though.. Mine is a top feed without passing through the grow media, I mainly do this for the waterfall type aeration it provides. With this type of system anything smaller then 1" causes problems in mid/late flower, due to the PVC being blocked by overgrowth.