Help, Water & Nutrients Changes

Hi everyone, I am going to purchase a system that I have added photos of below and I don’t know how I will change the water and nutrients in it, do I need a reservoir tank? Do I not need a reservoir tank? Any help is much appreciated!! Also, if I do need a reservior, where would I buy one from online? I live in Aus. Here are the Specifications below and photo of the system. Thanks everyone! Happy growing :sunglasses::+1:

SPECIFICATIONS

Under Current 6 XXL13

  • NUMBER OF ROWS: 2
  • NUMBER OF SITES: 6
  • PLANT SPACING & MODULE SIZE: 40β€³ Centers / 13 Gallon
  • SYSTEM FOOTPRINT (FEET / METERS): 4’6" x 10’10.5" / 1.37m x 3.31m
  • TOTAL SYSTEM VOLUME (GALLONS / LITERS): 80 / 303
  • WATER CHILLER SIZE (HP):* 1/4 – 1/2 HP
  • RESERVOIR (GALLONS / LITERS): 85 / 350
  • VEG TIME (WEEKS/IN.): 4-6 weeks / 30"-36"