yep.. i felt the same at first as I built a float valve into that system and had a line run right from my filter.
Got tired of guessing so I switched to letting it drop and just turning that line on every few days to week while I was in there doing other stuff.
A pump with decent head pressure, equal lengths, and step downs are the key.
Check the top pipes in my video above.
It comes out of the bucket down and runs to the back in a 1" pipe.
At the back it hits a T and each of those runs up to another 1 x 3/4 x 3/4 T.
Those runs go down along the rows of buckets. At each bucket there is a 3/4 x 3/4 x 1/2 T or L fitting that runs into the side of the site.
Short 1/2" piece of pipe that runs into the site with a 90 and a cap to make a sprayer.
Here's an older video from when I built it. before I added the trash can res.