Commercial Irrigation: From the Water Source to Every Plant

Size the system so every zone can give every pot a full feed, to about 25% runoff, inside the watering window you have. Work it out from the outlet back to the water source: outlets × flow gives zone demand, and the valves, pipe, filters and pump have to meet that at working pressure. We don't design around lots of small shots to stack EC; with CropSalt, concentrating the root zone can crash pH.

Work back from the outlet

1. Pick the outlet and count per pot. More than one emitter per plant gives you some backup if one stops. Two outlets per pot need twice the flow of one.
2. Work out zone demand. Outlets running together × GPH per outlet ÷ 60 = GPM. 1,400 outlets at 3.2 GPH is 4,480 GPH, about 74.7 GPM.
3. Choose the pump from its curve at your working pressure, not from horsepower or advertised maximums.
4. Size the pipe for the flow. Undersized pipe eats pressure; extra pump pressure isn't the fix. Pump curves, PVC friction losses and our 2-inch pickup, 1½-inch delivery layout are in Why we use Red Lion pumps and large PVC.
5. Filter after the pump. We use a strainer at the reservoir pickup and two parallel 200-mesh filters after the pump, with valves and unions so they can be serviced without shutting the facility down.

Batch tank or direct injection

Both work. We prefer a batch tank, especially when incoming water quality moves around: you see stable EC and pH before anything goes to the plants, the injectors fill the tank at their rated flow, and a separate pump handles irrigation demand. Direct to plants, the dosers have to keep up with the zone's actual flow and there's no tank to correct the solution, so check EC and pH at an emitter while the zone runs.

• Keep Veg A and Veg B, or Bloom A and Bloom B, in separate stock tanks, injected at the same rate: 1:128 (0.8% on the doser, about 30 mL of each concentrate per gallon of feed). We run two Dosatron D14MZ2 injectors, one for A and one for B, both at 0.8% and adjusted together. For the Cake finish, Cake runs through one injector and the other is off. Recipes: Mixing stock tanks.
• Into a reservoir or injector line, the order is Part A, Part B, bleach, then RunClean.
• Adjust pH on the finished feed, not in the stock tanks. The pH doser is a separate job from the nutrient injectors.

Keep the lines clean

• Particles: the filters.
• Mineral scale: RunClean at 0.2–0.4 mL per gallon, or used as your pH down. See What RunClean does.
• Sanitation: regular unscented bleach (6–8.25% sodium hypochlorite) at 0.2 mL per gallon of finished feed each time you mix and again every 4 days until you change the reservoir, dosed on the volume left; 1 mL per gallon in each stock concentrate; and a 10 mL per gallon shock of the empty system between crops with the plants disconnected, flushed before reconnecting. See Our bleach routine. Never mix concentrated bleach with RunClean (it can release chlorine gas), and never bleach a stock tank that has RunClean in it.

Design for inspection

Label every tank and line. Give each zone a flush point. Route drainage so individual pots and representative benches can be checked for volume, pH and EC, and measure the feed at a running outlet; the tank reading isn't always what reaches the plants. Catch-test the first and last outlets when you commission a zone.

Correct a weak zone

Catch-test near, middle and far outlets. If running fewer zones at once fixes delivery, the supply is short; fix zoning or capacity instead of adding runtime. Re-sample the finished feed whenever an injector setting changes. Step-by-step: When part of a room misses an irrigation.

Planning a build? Send us the medium, pot size and plant count, zones running at once, pump model, line sizes, emitter type and count, filter, reservoir location and a sketch. We'll check it against flow and pressure.