Air that is too dry makes a plant close its stomata, and then uptake stops even with perfect feed and light. It shows up mostly in winter, when heating dries the air, and under LED, which gives less radiant heat than an HPS lamp and therefore less evaporation too. The choice here is about tank size and about whether you want the water heated.
Tank size is refill interval, not capacity
The AC Infinity CLOUDFORGE range runs from 4.5 litres on the T3 through 9 litres on the T5 to 15 litres on the T7. That volume sets how often you refill, not how much moisture the unit puts out per hour. A 4.5 litre tank running low will last days; the same tank at full output will not. So choose the tank on how often you visit the space, and the output on the volume you want to humidify.
Cool or warm mist
This is the real difference in the range and it does not sit where you would expect. The T3 draws 24 watts and the much larger T7 draws 100, but the T5 in the middle draws 330. That is because the T5 alone heats the water and can therefore produce both cool and warm mist, with ten mist levels and ten heat levels. Warm mist settles less readily on your leaves and helps in a cold room; cool mist is cheaper to run. The T3 and the T7 atomise ultrasonically and cold.
Running themselves on humidity or VPD
All three work with a probe on a cable, so you measure at canopy height rather than inside the appliance housing. They switch themselves against a humidity target or on VPD instead of running continuously, and they connect to AC Infinity's own controllers. To make humidification, extraction and heating behave as one system, the controllers sit under Measuring & Control.
What is in the water matters
An ultrasonic atomiser puts out everything dissolved in the water, limescale included, and that settles as a white film on your leaves and your equipment. With the larger tanks it happens faster, simply because more water goes through. The manufacturer therefore states which water to use, and that advice sits per model on the product page.
Frequently asked questions
Which size suits my space?
Choose the tank on how often you want to refill and the output on your volume. For a single tent the smallest is enough; for a whole room or a week unattended, take the largest.
Why does the middle model draw the most power?
Because it is the only one that heats the water. Heating costs far more than atomising, so consumption here follows the function rather than the tank size.
Should a humidifier run continuously?
No. Let it switch against a humidity target or on VPD, otherwise you overshoot and work against your extraction, which is removing that moisture.
