I would love to do an RDWC, I'm a DWC grower and I always end up with my buckets at different heights so they are all at the same height at the canopy. You know what I mean, some plants are just shorter than others and grow at different rates. Of course if you grow all the same strain the height will be homogeneous, but if you grow different strains, how is an RDWC possible?
So what I have done in the past when growing different strains together (soil) that I did a lot of LST (low stress training) of the plant. Things like topping and tying branches down to spread things out and get lots of colas and an even canopy.
I am now in RDWC and basically do the same thing to get my canopy as even as possible. It takes a bit of practice and I am by no means an expert but I am getting better every grow. To date, I have only ran a single strain at the same time but am getting ready to start a new grow where I am running two different strains in the same RDWC system. I will do the same thing in training to keep my canopy even if one or the other tries to grow too tall.
Keep in mind that just because you might grow the same strain, especially from seed, you are very apt to get different phenotypes that you will have to train the very same way because of variances within the strain itself. Even clones from the same mother can act differently in the same system I have read.
You are more likely to have issues running different strains in the same hydro system with regards to nutrients because different strains often have very different needs nutritionally. You have to find that balance if this occurs and give and take to find that middle ground that works for both/all strains. I think the same thing could be said about lighting. You have to know how to read your plants.
