what you describe is know as DWC or Deep Water Culture. it should work okay assuming the air pump runs constantly but the real question is support for the plant- how will you hold a large tomato vine up in a bucket of bubbling water. (blocking light from getting into the bucket is another concern)

sounds like you are on the right track- you can syphon the water out with a tube if you do not want to "pour" it out (again what will you do with a 5'+ tomato vine while your dumping the bucket it was growing in?) you do nto nesicarily have to get 100% of the water out at every change just shoot for 80-85% water changes and if you ar going to b syphoning off the water i recomend liquid nutrients to the undisolved salts of the powders dont build up too badly on the bottom and sides.

remember- we want pictures of the construction and implimentation as well.

good luck and if you have anymore questions just ask.

Thanks for that info. I think i'm going to give it a shot.

I do have a solution for supporting the plants. I don't think i've seen anybody else do it but i'm sure it will work. I'll be sure to post some pics once I get everything built.

Thanks again for the help!

To answer your question about the nutrient solution for your DWC Tomato system, it is recommended to use Chem-Gro Tomato Formula 4-18-38 and adding different concentrations of Calcium Nitrate and Magnesium Sulfate according to growth stages, i.e. seedlings stage,second flower cluster to 4th cluster of flowers and at 4th cluster of flowers and older plants. you can get all the details from Hydro-Gardens, Inc. http://www.hydro-gardens.com
This is a soluble complete balanced Hydroponic Formula.
1/4 tespoon of Chem-Gro dissolved in one gallon of distilled water will be about 300 ppm, of course when you add the other salts ppm will shoot up.
We are waiting impatiently for a follow up.
Best luck to you.

1. Are you going to put this on your deck? or by the the glass door going out to the deck?
2. If you can find a local hydro store in your area, they have 5 gallon black buckets with lids that have Net pots built into the lid. Very nice. Or get a 3.5 gallon bucket, and some plastic spray paint black and white. Spray the bucket and lid with black first, let dry and then spray it white.. You have to block the light to your rez, or bucket, or you will get alot of algea in your water. You can cut a hole in the top of the lid to hold your net pot. Get some hydroton, or clay pellets.
3. Use blue, or Black air hose. You can use a variety of air stones. You will want a minimum of a dual outlet and get 2 air stones in each bucket. More oxygen in your water the happier your plants will be.
4. If you can locate a hydro or Indoor gardening store in your town, get your nutes there. You really want nutes, that are made for hydro as you will need to watch your PH and PPM, levels in your water. You will need ph up and down to keep it level. Look into a organic line. You will be eating these, and in hydro, you have a perpetual grow, and unless you are starting over every harvets, you will not be able to flush the nutes before you eat them. Also, it will give a better flavor to the final product.
5. Are you going to use RO, Distilled or Tap water? check your ppm or water hardness level. Most city tap waters are very hard. Lots of problems will occur in hydro setups with tap water. I would recommend you get a RO filtration unit for your sink, or find a local grocery store that sells bulk filtered drinking water. You will have less headaches. trust me on this one. if you have to use tap, buy a couple gallons of filtered drinking water and let your tap sit 12 hours and add a 50/50 mix. You can find nutrient lines that have a hard water micro solution. If you don't get the water/nutes right, you will get lots of nute lock up and or they will burn up.
6. You can get a solution called CalMag+, to suppliment your nutrients. Use it if you go with ro or distilled water. you won't need it as much in the veg stages, as you will in the flowering or budding stages. Tomatoes will eat it up.

I would recomend a little testing and trial/error before spending alot of money on an R/O filter. I'm using city tap water and have been doing quite well with my small hydro set ups. You can get reports about city water to get an idea of what's in it. You can also test the PH and EC/TDS/PPM of your water to see how much it will affect the solution. Our water here is just above 7 on the ph scale most of the time and so long as we let it sit or bubble for a couple of days before using it the chlorine isn't a problem.
You may find that your water is too hard or far off on the PH scale which would make you concider spending the money but it probably won't hurt to try without first.

safwat: I plan to try the Hydro-Gardens Tomato Formula in the near future. I notice that this is a 1 part mix. Why wouldn't the calcium, phosphorus or sulfur precipitate out of the solution? Heavy concentrations of calcium nitrate and magnesium sulfate will form a precipitate of calcium sulfate (gypsum). Calcium and phosphorus will precipitate to calcium phosphate (cement). Can you explain why this doesn't happen? I can only think that the amounts of each chemical are very small compared to the volume of water used. Did you figure out the 1/4 teaspoon per gallon? That is a very helpful tip. Thanks for your post.