Auto pots or not?

You could just get a reservoir, pump, and drip kit and use these with the current planters you have. I use the 3 gal bucket and drip kit from The Bucket Company, they have the manifold option as well which I may upgrade to. The planters/buckets are good quality. If you use any drip style irrigation, make sure to use water soluble nutes in your reservoir. I'm currently using 6 buckets in a 8'x4' but I could comfortably hold 12 buckets, 18 buckets would stuff it full. Is 750x750 in mm? So roughly 30"x30"? If so 4 of the 3 gallons bucket company planters would fit. If you ever want to go to a 4'x4', 6 of the 3 gallon buckets would fit.