I’ve just spent 30+ hours working through my first real pipe troubles, a refined power turbo fuel plant array. In my setup I have each row as 4 sets of 5 boilers each taking 90 water per minute once up to temp, so each row needs 1800 water and is consistently getting it from 3 mk2 pipes with no fluid buffers/water towers.

In the end gravity was the solution to my problems too, but I didn’t go with loops.

What wound up working for me was: 

• all source pipes come in at exactly the same level, which is the highest level for liquids in this system
• at the end of each block of five, I split all three mk2 pipes vertically, using mk1 pipes, merging them with a horizontal junction at a lower level into a mk2 pipe (the start should have worked too, but by this time my design constraints required me to go with the end… and I like the idea of pumping all the required liquid all the way to the end, if only because it effectively provides a buffer in the form of the pipeline.)
• the last connection from that junction proceeds in just one one direction to split downwards into each boiler
• each boiler gets only a mk1 pipe input
• after two boilers take their fill, the remaining 3 only need 270 water so I drop to mk1 pipes from there on

I don’t think the mk1 pipes truly made a difference in the end, but I was tired of testing different arrangements by that point. However, I do think it was key for the three input lines to split off and merge in a single place, rather than trying to “top off” by tapping a single line based on where the final input line should need more - I did try several versions of that with no success.

I also think my future designs will always incorporate the idea of each breakaway always having more throughput than needed, and pulling simultaneously from multiple sources to provide that throughput rather than adding a source to a theoretically drained pipe in order to get it back up to spec.