There are some drip systems that use a air
pump to raise water up to the drip ring, they seem to work OK for single plant systems, but will get quite complicated to expand into multiple plant systems. I have never used an air pump for water flow in a
drip system myself. Also those systems require a reservoir just below the bucket holding the plant, and naturally because of space those reservoirs are usually small. Then in order to increase the reservoir size it would require a water pump to circulate water between a larger second reservoir, and the smaller one just below the plant.
I posted this link before (
http://www.hydroponicsonline.com/for...w-systems.html), but this drip system is about as simple as it gets for me.
Simply put it uses 5 gallon buckets filled with
growing medium for the plants roots. The water (and
nutrients) are pumped up to the top drip ring, and slowly drip out soaking the growing medium on its way down to the bottom of the bucket. At the bottom of the bucket is a through hole (also called a bulkhead fitting), big enough so the water will drain out faster than it drips in (so the water wont back up in the bucket). That drain simply runs back into the reservoir, where it gets pumped back up to the drip ring again. If you want I can e-mail you my complete instructions on building it. If you want me to e-mail you the instructions, click on the link to my website in my signature "Home Hydroponic Systems" and send me a e-mail to the address on the contact us page asking for them. It's not complicated, but the instructions are in PDF so I'm unable to post them to this forum. The system I built is for 4 plants, but it's easily scaled to as many plants as you want. One plant, or twenty plants, the principal is still the same. The only real difference would be the size of the reservoir to accommodate more plants.
The reservoir I used for this system is the 18 gallon storage tote I got at wal-mart for under $4, but in the future I would use a larger reservoir for 4 large plants like that (live and learn). Each plant could drink as much as 2 gallons of water a day when they got large, and that caused huge fluctuations in
nutrient concentrations because combined they could drink almost half the reservoirs water. But for 1 or 2 plants that reservoir size should work OK for plants that big (you don't need to fill it to the top while the plants are small). And it's real easy to switch over to a larger one later if necessary.
P.S.
You don't really need special drip emitters (fittings). They just tend to clog anyway, as well as a need a certain amount of back pressure to work also. I just cut the tubing to size for the drip ring. Take a paperclip and heat the tip with a candle, then poke some holes in the tubing for the water to drip out of. Again real simple, and cheep.