man those are going to fill that grow area. I'd give one away or juice it or something so you have room to work and grow. I have a 4x4 tent and I only plan 3 plants in there leaving room to work and a large oscillating fan and I don't think Ill push 4 plants in there.
I converted from DWC to a RDWC system and am blown away how awesome it is working. No more fucking around filling buckets and lifting plants and root balls and lights to do checks. I went with a 100L external reservoir though I only fill it to the return drain line which is 40L though I could go to 60L. No going back, its fucking pro.
My research made cococoir Drain to Waste very appealing for said reasons but I love hydro and I absolutely love RDWC!!!
Lookin good man.