Daisy Chain the siphon outlets?

[Eleven11]

You could get them to drain in a certain order at first but they'll all drift out of sequence. It's best to go with a gutter type design.

Is there a way to configure the system initially to drain in a certain order, and then leave it that way so that you always know that one will drain x-minutes after another? I was really hoping the one pipe connecting all three would be a good solution.

[Bioritize]

I would think that you could tie all three beds together with a header that was in this case 3 times larger than the drains. Then use the same idea of an external siphon on the side. All three beds will fill at the same time due to the common drain and then when it reaches the right height, in theory it should drain everything as though it were one tank.