tmc lighting for our tank?

[Simon S]

our tank measures approx 5.5" x 2" x 1.5" (L x H x D).
approx 400L capacity.
how many 1500 ultima tiles would you guys recommend for this?

i am thinking 4 !

since starting the tank in september last year we have been using 6x tmc 600 grobeam strips but suspect this is not enough. hence the reason our plants are not doing too well.
ie. any red plants we have tried lose colour quickly.
we are using pressurised co2 and ferts.