Real78,
First, all of the previous posters have good points and concerns, but I don't think any of them have used generic waterfarm systems versus GH's commercially produces WaterFarm Systems.
Let's eliminate the Ebb and Flow right no if height is a concern because the growing container is going to have to have the bottom of the pot or bucket higher than the level in the reservoir so that the solution can drain to the bottom of the grow container. For example, let's use a rez with a solution level of 8" from the floor when all of the solution has drained back into it. That means that the grow container's bottom must be at least 8" or higher from the floor in order for all of the solution to drain out.
On the other hand, assuming you can control the temperature in the container, the bottom of a DWC, either the bubbler style, the mister style, the drip style or waterfarm style, can actually sit right on the floor so right there we have gained at least 8" using our previous example, in available growth height for the plant. The argument can be made that even a 5 gallon bucket is too small because the grower might not want to have to refill/top off the reservoir more often than once every 2 weeks or longer.
As long as you are willing to keep the reservoir full, you could even grow in a smaller bucket than 3 gallons if you want to do so. If having to refill/top off the reservoir too frequently becomes a problem, you could always use some kind of remote reservoir to keep the grow container solution at the desired level.
The point about the 3 gallon/2 gallon combination in a waterfarm is based on the commercially produces version marketed by General Hydro. I could be wrong but I think they actually use nearly a 4 gallon or bigger reservoir bucket with a net pot of nearly 2 gallon capacity that sits part way down in the outer bucket leaving approximately 3 gallons of solution capacity.
I'm pretty sure that I read somewhere on the GH website that the individual buckets had a 3 gallon SOLUTION capacity.
If you use a 3 gallon bucket, then at the most you are going to have a 2.5 gallon solution capacity after you allow for air space at the top of the container. If you can live with only having 2 gallons of consumption by the plant before you have to refill/top off the reservoir, then yes you could use 3 gallon buckets.
Of course you could always use a central control reservoir with a controller to maintain your grow container at any predetermined level you want and then it would be the capacity of the the control reservoir divided by the usage of the plants that would determine the frequency with which you have to refill or top off the reservoir.
If you want more information about the generic DIY versions of waterfarm systems or other DIY DWC systems, please check in the DIY section.
There are many options for a DWC system both in the DIY section and elsewhere in the Hydro section, everything from separate buckets, with and without controlled central reservoirs,to tote beds to large -- over 5' x 5' -- beds/tables and just about anything else you can imagine.
There are probably as many if not more growers using a variation of DWC at least as successfully, as any other form of hydro, if not maybe all other forms combined.
Most of the ebb & flow growers that I know personally use it not because it works any better but because they jut like it better because it is somewhat closer to dirt/soilless (Black gold, coco and so on) growing and they aren't comfortable with constant wetting of the roots.
Theoretically you could grow hydro in a 0.5 gallon DWC system if you could keep oxygenated solution provided to the roots.
Good smoking.
