putting together an NFT system for lettuce using vinyl downspouts. What size should the feeder tubes for the channels be? And what diameter for the manifold? I'm shooting for about 1 liter per minute flow. I have plenty of pump and could always divert some pressure back to the tank to oxygenate the tank. Systems I've seen online all have two feeders per channel in case one gets blocked. They appear to be 1/8 or 1/4 inch feeder tubes. I suppose I could start with 1/8 and re-drill the holes if I need to make them bigger. Of course I would rather not re-invent the wheel! Any help would be great