Many pre-built DWC setups utilize 5 gallon buckets, which I feel are too small for a full-sized cannabis plant. One of the main advantages of DWC is that you can leave the plants for days, even weeks, at a time. This is why I like to use large 17 gallon totes, like the one pictured below, for my DWC Reservoir.
Overview
Air Pump Comparison Table
How Much Air do you Need for DWC?
A good rule of thumb for DWC airpump size is to have:
~1L/min for every gallon of water
or ~17GPH per every gallon of water
15/25L Hydrofarm Pump
For a 17 gallon (77L) tote you need a 6W 15L/hour 4-outlet pump like this Hydrofarm ActiveAQUA model that I run. These pumps are whisper quiet and I love using them.
For a dual tote setup (typically 480W Printed LED Board) you can choose between running 2x 6W 15L/min pumps or a single 12W 25/L 8-outlet pump pictured below:
Note that there is no shutoff for the air valves on these pumps as there is with the VIVOSUN models below. This means you will need to run 4 or 8 airstones with separate hoses running to each.
VIVOSUN Metal Air Pumps
The next step up brings you into the metal case class of VIVOSUN air pumps. Be forewarned that these are MUCH louder than the Hydrofarm pumps pictured above. If noise is an issue some say that attaching a hose to the air intake of the pump helps muffle it down a bit. Still these pumps are very loud and should be avoided if you are sleeping near your grow.
The VIVOSUN 32W 60L/min and VIVOSUN 50W 70L/min are excellent options for a DWC up to 70 Gallons (4 totes @ 15 gallons each). The wattage does not exactly scale properly with the air output, I would grab whichever one is cheaper. This pump would coincide with a setup running 480W – 960W of Printed LED boards.
For extremely large home grows (5+ totes) you should look into the VIVOSUN 102W 1750GPH 110L/min. This beast will run even the largest of DWC or rDWC setups.
Air Stones & Airhose
The best airstones I have come across are these VIVOSUN Large 2″ Airstones. They are not likely to break like the flat long ones, take well to boiling for sanitization, and have a thick exterior for cleaning.
As far as airline goes get a minimum of 25′ of blue airline. For any of the pumps with more than 4 outlets I would get 50′ or even up to 100′ of airline if you can find a bulk spool on Amazon. I have tried clear, black and blue airline and can confidently say blue is the best colour. Clear airline lets in light leaks. Black airline gets warm from the lights. This causes black airlines to build up slime and biofilm inside the DWC container that can lead to root rot. Clear airline will work but black is absolutely the worst colour to use.
Air Pump Placement
For safety the air pump should always be placed above the DWC reservoirs. In case of a power failure you do not want water to flow back down the airlines potentially flooding your grow.
If you have having trouble keeping your reservoir temps below 68F try placing your pump outside of the grow room. Pumping warm air through the totes will increase temperature, so keeping the pump outside will help keep those temps down. I have never needed to run my pump outside of my grow tent and can still keep water temps about 10F below ambient daylight temps by painting the container white and keeping it topped up to at least 50% capacity throughout the grow.
