Sizing a grow room dehumidifier
Dehumidifiers are rated by how many litres of water they remove per day under test conditions — the Trotec TTK 100 E is rated at 30L per day and the DH 25S at 40L. Real-world output is lower, because the rating assumes warmer, wetter air than most grow rooms run. Size up rather than down, particularly for a sealed room or a late-flower canopy transpiring hard.
Where the moisture comes from
Almost all of it is the plants. A canopy transpires most of what you feed it back into the air, so the humidity load rises with plant size and irrigation volume. That is why rooms that sit comfortable in veg become a problem in late flower on the same equipment.
Ducted, VPD-aware or portable
The AC Infinity Hydrone 5 is dual-duct and integrates VPD control, so it can be plumbed into an existing setup and run against a target rather than a humidity number alone. The Trotec units are portable and straightforward. The Quest 70 Hang Kit lets a Quest unit hang overhead and free the floor — worth noting the Quest 70 itself is currently out of stock, so the hang kit only helps if you already own one.
Monitor with a hygrometer, and see humidifiers if your room runs dry instead. Extraction does part of this job too — see fans and blowers.
