Grow room cleaning between crops is the least interesting job in growing and one of the highest-return. Pests and pathogens overwinter in the room, not on the plants – in the corners of the tray, the pump housing, the folds of the tent liner. A crop that starts in a dirty room inherits the last one's problems.
The between-crop reset
Strip it out. Everything leaves the tent – pots, trays, fans, hangers. You cannot clean around things.
Dry sweep first. Dead leaf and spilled medium are where fungus gnat larvae live.
Wash the tent liner with a mild steriliser. Pay attention to the seams and the bottom corners.
Flush the system. Reservoir, pump, lines and drippers – biofilm inside irrigation lines is a pythium reservoir and you cannot see it.
Wipe the fixture and fans. Dust on an LED costs you real output; dust on fan blades costs airflow.
Leave it dry. A closed damp tent grows mould between crops.
What to use where
Tent surfaces and equipment: a horticultural steriliser or dilute hydrogen peroxide.
Irrigation lines and reservoirs: a dedicated system cleaner, run through and flushed thoroughly. Residue in a line will reach roots on the first feed.
Between plants during a grow: alcohol wipes for tools and hands – see propagation tools.
One warning
Sterilisers and beneficial biology are mutually exclusive. If you run beneficial bacteria or enzymes, clean thoroughly between crops and then reinoculate at the start of the next one. Do not run both at once and expect either to work.