Is this irrigation build alright?

I was planning on using Hunter for the irrigation controller + pump start relay, but might choose TrolMaster's Aqua-x since it can control multiple pumps/devices, so I could control the veg room too. Not sure yet, but is the design itself good? Is there anything I'm missing?

Pretty high tec. Drain to waste obviously? Seems good, at a glance the only thing I can see that might be missing is a valve on the res side of the manual flush valve

How many plants do you plan on running?

I have a design for up to 16 plants, I normally run 5 to 12 in coco DTW.
If your interested let me know.