Yes, all the instructional sites about bell siphons tell you about the water pressure. I haven't found that to be too difficult to deal with, as the $10 pump I bought has an adjustable flow built right in and I was able to dial in the flow. If you get a pump without an adjustment, you can just add a "T" with a ball valve to control the flow.

My next questions for you are:
1) Do you feel like the plants last to get the water (bottom) receive less nutrients than the ones at the top?
2) Are you using the pre-made vertical posts with the filler material and special zip hook, or have you built your own?
3) If you are constructing your own, what material are you using for the plants to grow in?
4) When you remove a plant, do you have to remove ALL the grow material, so as to clean out the plant's roots?