Yes, 1 tank per tray. Each tray is about 4' square, holds ~20 8" dia pots. Trays flood to about 3" (150mm) deep. Each tray does have its own tank so the nute mix can be suited to a plant in a specific 2-week time band in the flowering cycle. Tank/tray 1 is mixed for just-rooted cuttings, from week 0-2. Tank/tray 2 is for week 2-4 and gets a slightly stronger mix than #1. Also gets a dose of Canna PK-13-14 in wk 3.

Tanks are a little bigger than they actually have to be to keep the pumps submerged while flooding the trays (could probably be as small as about 70 litres) but I use 125 litre tanks, just plain old plastic storage containers.

The mothers are in a very small tray (about 1' x 4') with a 35-40 litre tank.

Canna Vega Substra for the mothers, Canna Flores Substra for flowering, Canna PK-13-14 phosphorus additive in wk 3-4. Pathogen control with hydrogen peroxide (50% strength) @ 1ml/litre every 3-4 days when topping up tanks with plain tap water... and nothing else. No wacky magic sauces, no crazy beeswax and brewers yeast additives or other silliness.

I even find I have no general need to adjust pH after mixing up with Canna nutes- pH is always right on 5.6. pH may bump a little after a couple of top-ups but rarely goes above 5.8.

Not mentioned in my setup data is the ventilation system. Veg and flower have independent air systems which can change the whole air volume in each every 2-3 mins. With 2kW of lights in the flowering area, this is about the minimum needed to keep temps stable without using aircon.

There's oscillating circ fans in every corner of the flowering area and a fluorsescent UV ioniser (with light trap) which runs 30min on/30min off all hours- keeps scent and mould well in check. A second ioniser in the area outside the room istelf guarantees no stray scents escape.