No I hadn't seen your drawings before, wish I had. I copied a commercial strawberry system I saw on-line. They built theirs in a greenhouse and had rows after rows of the towers. They used 6" pvc and I used 8" because I also thought that was a little close. They also utilize a run to waste
drip system and I chose to recirculate the nutes so I added the bottom part. It is working well and the plants are growing. I will look at your design before I build the other 3 towers. I have not yet buried the nutes so they are in a temp bin but I plan to use a 55 gall barrel.
I did not use net cups and planted directly into the perlite just like the commercial system. It took about three 5 gal buckets to fill the tube. You fill to the bottom of the first row, add plants and fill to bottom of next row and repeat. Goes pretty fast once you get use to it. You have to rinse the perlite first and I made sure the crown? part was out of the tube since they don't like to get wet.