Hey there, I am in the process of getting my grow going which includes my DIY undercurrent system with (3) 5gal buckets with a 5gal epicenter. I have these 3 buckets lined up in a row. I currently have the undercurrent system set up as to make a entire loop around using 1" black tubing. When the pump in turned on it drains the bucket on the left before enough water can make it through to even out all the buckets, and the epicenter overflows. I and altering the setup of the buckets and pump lines. I have a couple blueprints(powerpoint made) of how I currently have the setup and then I have the new version of what I plan on changing. I would like to get some feedback on whether my changes are likely to work before I start hacking up tubing and buying PVC. Heres the visuals...
From what I've seen with undercurrent systems, is that the link between the bucket has to provide a lot of flow. I've seen a setup with 2'' pvc through all of the buckets, I think that'd be the best way to go. 1 inch water line can't push that many gallons per minute, it's limited. If you throw a large 2'' pipe through it all, there isn't a whole lot of resistance, and I have a feeling your epicenter wouldn't overflow at all.
I built one, might be worth checking my signature to see some of the details of my system. I built mine using 2" PVC, and only a 250gph pump. I'm not a fluid dynamics whiz, but based on your drawings, it looks to me like the epicenter bucket isn't draining fast enough. To fix this, what I'd do is: 1) Run two large diameter (1.5 - 2" ish) drains in your epicenter, of equal length. One each going to the end buckets. So if you filled up the epicenter with water, it would drain into the two end buckets, and then into the middle bucket. 2) Draw/pump water out of the middle bucket, and into the epicenter. This should be a smaller 3/4" or 1" pipe, depending on the flow of your pump. If your pump is set up to connect to 1/2", adapt it up to 3/4". If your pump is set up to accept 3/4" pipe, adapt it up to use a 1" line. I don't have time right now, but later in the day I can draw a diagram, if it would be helpful. Let me know if you have any questions.