Hydrofarms are often called 'waterfarms' man. They're a form of drip system as you already know, the power for the water's circulation coming from the usage of that airpump, of course. Airpump waterlifts of this type are called an 'airlift pump' because of the method of water movement, and the mechanism of an airlift has a lot of good properties that aren't found in straight pump-based water movement systems.
Now: in general, the biggest benefit of airlifts overall, is the fact that air rises on it's own, and this defiance of gravity in a column of water, provides lift. The air bubbles rising, drag water up behind them, as the water seeks to refill the empty space behind the rising bubbles, and the surface tension of water creates a mini-seal that keeps the water's rising, when the airlift mechanism's riser pipe is small. Water, although we don't think of it as being particularly sticky - we use it to wash away substances like jam, syrup based on sugar, actually has a well known high surface tension which is capable of creating a very efficient seal, when air bubbles are interspersed between little columns of water they are simultaneously dragging/pushing upward in a relatively small diameter, and especially - round, smooth sided lifting pipe. The riser pipes on airlift pumps are often referred to as the 'tube' because of a natural inference that 'tube' is used in small systems because typical pvc pipe, is only available commercially in a 1/2inch inner diameter; but 'lift tube' and 'lift pipe' are one and the same. It's just a matter of the inference derived from a hobbyist's smaller size unit, or a water well using a huge airpump and 3 inch iron pipe to lift water from several hundred feet below ground.
[*edit*] below I mention the usage in well pumps again, and it's a function of lack of time for proper editing for content. Forgive the repetitive mention of the same subject; this mention of wells etc derived from an expansion of the above paragraph.[*/edit*]
The power savings in the usage of airlifts in general pondwork etc can be substantial. The pumping of air into water, then allowing the air to rise on it's own, reduces the power demand. The constant exposure of the water as the bubbles slide up in the pipe also exposes the water in a very thin-film configuration to atmospheric level oxygen and creates good oxygenation.
In large water handling situations such as fish raising and stuff like that, multiple riser pipes, and a large air pump, provide a lot of savings in power usage.
in small hydroponics setups like a hydrofarm -again remember if you look them up online and read about them, 'airlift pump' and 'waterfarm' will help since 'hydrofarm' is a trademark name -
hydrofarms are noted for being easy to use. They're not as easy as a passive hempy bucket but they give great growth, and they are famous for being root-rot resistent. They're also known for the low power usage & aren't particularly loud. (I haven't used one I just know about them)
The benefit of the hydrofarm stems from not needing to chill the roots, and as an active root-drenching mechanism, it can keep a large quantity of root area bathed in solution, and that solution drizzling down through the media also tends to be well oxygenated, giving good gas exchange for the roots system.
In oxygenating water, the laws of thermodynamics determine the quantiy of gas exchange in the water. Atmospheric air has a quantity of oxygen far, far higher than water itself will hold; and exposing the water to this much higher quantity of oxygen in the atmospheric air creates a big difference in the two, relative amounts of free oxygen atoms: this natural difference is summed up roughly in the old saying 'nature abhors a vacuum' and that statement made by someone long ago and famous, is representative of the fact that where there is a large quantity of one thing in an area: it will tend to migrate toward an area where there is much less; the greater the difference the faster this migration occurs, until equilibrium, or - as close to equilibrium as the mechanics will allow - occurs.
Water won't hold as much free, loosely attached oxygen atoms as air will, so it never contains anywhere near the same percentage - but the drizzling the water in a thin film, exposes much of the water to a lot of atmospheric air, giving the water time to exchange gas: and good oxygenation occurs.
Root rot is a pseudo-fungal growth that'll survive in atmospheric air in it's spore stage, but once it makes the commitment to expand outward and create an active growing organism/colony it's vulnerable to high oxygenation; because the oxygen's charge will overpower the cellular walls of the pythium and exchange charge; killing it.
Hydrofarms' advantage that they are root rot resistant save cost on chillers; and give flexibility to hydroponic growing not seen so easily in a lot of other types of hydroponics; for instance one can be set outside, without need to manage reservoir temperatures. They can be simply unplugged, and carred from spot to spot; there's no plumbing to seal, no expense of said plumbing, and generally, water handling volume is reduced a lot. Small amounts of hydro nutes can be mixed up in a bucket, then poured into the farm every few days, and if someone is enterprising, it's fairly easy to make one self top-off using a small pump and a timer. The lack of high specification for precision makes them popular especially with beginners.
The lack of precision in topping them off eventually leads to a lot of people trying other methods once they get the hang of hydroponic water management; there's also a relatively, lot of medium to be cleaned each time the grow changes out at harvest. One, two, or three might not be that much but when people want to reduce the ultimate tie to the rather large quantity of medium, hydro/waterfarms often get set aside for things like ebb & flow tables, gutter systems etc where each plant doesn't have such a large amount of medium.
One big advantage to hydrofarms I've see is the ability of beginning hydroponics people to grow great plants, and also, grow pretty large plants in them. There is also an easy way to add to the growth of one, and that's to add air stones into the bottom down there, so the water bubbles upward in a film. This adds about a fifth to maybe a fourth growth to one, albeit at the expense of the airstones, the extra air needing to be pumped, & all that.
One of the most famous early forms of growing huge trees was done by a guy named Krusty who formed the 'KFB' system called 'Krusty Freedom Buckets' and they are very similar to a hydrofarm on steroids. A chiller is used to ensure there is great root rot resistance and oxygen retention in the water, and an overpowered air pump used, along with a reservoir to feed a lot of plants. Also vertical lights hung around the trees comprised part of that system and it was a true commercial growing system; although it had a lot of maintenance and expense associated with it.
The primary principles of a hydrofarm with air in the bottom are quite similar. Krusty buckets used a water pump only for the drip feed, and the massive amounts of air fed into the bottom, caused the water to bubble up and film the roots. The huge amount of air exchange down in the zone created good gas exchange capacity for the roots, and growth was adequate to ensure huge plants could be grown.
Hydrofarms having a large area for roots to spread through, an adequate supply of water in the bottom, and a lot of oxygenation throughout the medium mean it's also used for tree or larger type plants a lot. The bucket's weight and relatively large amount of medium anchor the trees well, feed them well enough.
There is a version of drip called the 'Bato bucket' which is again a drip system. It's basically just a straight drip; it's not airlift driven, and the buckets are all connected with a drain at the bottom feeding back to the main reservoir.
Bato buckets aren't hydrofarms because the hydrofarm's signature component is the airlift drive.
For somebody who hasn't grown with one that's about all I know about them. They're a really good start up for hydroponic growers; they can also be manufactured individually very cheaply; since, if you ever take yours apart, you'll see the only components to them are the riser tube, the fitting that distributes the water in a ring typically around the base of the plant, and the air tube that fits down into the riser tube.
These can be built by hand very, very easily; since all that need be done, is the riser tube selected, a few notches cut out at the bottom so it'll draw water in as it sits on the bottom of the mini-reservoir, and about 3/4 of an inch from the bottom, a small hold drilled into the riser tube, and an air tube stuck into that hole.
At the top, a "T" fitting is set onto the riser tube's top, and a piece of tubing is stuck on in circular manner around the base of the plant, and in the TOP of that simple loop of tubing, holes are melted/drilled/cut. What this does, is allow for the air to escape as well as let the loop of tubing forming the drip ring to be leveled, and then the water rising out all drizzles out the holes around the loop, on top. If you put the holes on the lower, bottom side of the little loop of hose going around the base of the plant, stuck into the two ends of that "T", then the water would come up, roll out into the loop, and immediately fall out of the nearest holes; typically giving less round coverage, making the water drizzle more down one side of the root zone. Putting the holes on top, means only when the whole tube is filled, does the water roll out: and since the top of the little loop is easy to level, good coverage can be had.
There's another aspect; if the holes are put into the bottom of the drip loop, the air tends to build up. Once it's dragged/pushed the water up to the top, it can be released right away. This eliminates back pressure which allows for as much air as possible to drag as much water up as the pump can do; and it reduces the sputtering & popping sound somewhat.
If there is so much air being fed in, as say through a large commercial air pump, strips of plastic scrubber pad can be cut just wide enough to cover the air holes, then tacked onto the top of the drip rings with hot/super glue so the splashing is minimized; although I've never heard of someone needing to do that.
I mention the method of release of the water and air, because when you google 'airlift' or 'hydrofarm' or 'waterfarm' you'll often see a mention made of an air release at the very top of the riser, which lets the air go up, past the point where the water spills out of the waterlift tube. This is done various ways; and is most typically seen on large systems where the amount of air is truly very large, as in yard systems for making mini-waterfalls for ponds, etc. In these instances, the builders often just ramp up the entire physical build: air pumps are many watts, and pump huge amounts of air relative to a hydrofarm. The riser tubes will be 2, even 3 inch pipe on true commercial fish farms; the amount of air coming up is very large, and the water isn't released into a drip loop: just out one hole. When this happens, if you think about it, it's possible to have the "T" put in sideways so there is a connection to below, where everything rises up, and the water spills out to the side thru one hole: but the top of the T is left open, and the air simply comes out the top without following the track the water does, in a hydrofarm/diy hydrofarm setup.
In fish farming or waterfall creation it's only necessary to get the water up, then it can just fall out one hole. But when farming plants, you want the drip ring configuration so you can spread where the water falls; so it becomes a matter of how you orient the "T" at the top of the riser.
A good amount of reading on airlift pumps, will be a huge eye opener to most non water management experienced people. Even water wells use the airlift configuration to pump water up from hundreds of feet below the ground; and if you realize that airlift pumps are both simple and used in a variety of ways, you'll understand an aspect of water handling many people don't ever learn well.
I worked in aquariums when I was a kid, my parents owned a pet shop, and the 'airlift pump' is what makes air bubbling up in those little clear riser tubes in aquariums, drag water through the filtration pumps: both the in-the-water box types, with the floss and charcoal, and the classic 'undergravel filter' configuration used in so many aquariums.
Just a primer for reading purposes nothing more
