don't tell me you also planned the wires on the ceiling... seems like a very clean set up-no wires exposed. very envious of the nice job. mind me if i ask you.. the metal square you had welded, are these 2.5cm x 2.5cm or bigger? looks really sturdy and light. i had my 180 gal (6x2x2) stand made from 8 pillars of 10cmx10cm wood. and it was as heavy as it can be. i regret using wood... i might go with steel for my next project on a big tank. at least it does not warp if it got wet and besides.. with powder coating rust and a good amount of layered enamel paint is the last thing in mind...
nice to know you will do some plants. with your lights, i don't see any need for CO2 unless the plant is intermediate to hard on keeping they alive. now, i am no expert on plants.. i just notice that if the tank is has plenty of lights some low maintenance plants grow like weeds.