Hey mikee,
welcome to the forum. with an EnF sytem the medium does not need to stay saturated for 30 minutes. it simply need to be flooded long enough to get the medium wet. some simple timers have a minimum 30 minute on cycle (though most are 15 minute)so, depending on the volume you're trying to flood, you set it to the next highest time required. For me, a 15 minute cycle is plenty to flood a 48"x24"x3.5" tray. but that depends on your pump characteristics.
To keep the tray from overflowing, you install an overflow pipe. this pipe will control how high the water level rises.
The pipe should be large enough so there is no chance the pump can put more water in than the overflow can release. For my setups, I use 1.1/2" overflow and have never had a problem.
this sketch may help:

Also, you don't need to run it 4 times a day. you only need to run it enough to keep your medium moist. For me, I flood them once or twice a day last time, but I was using coir as a medium.
And finally, to keep keep the tray from emptying faster than it is filled, just use a small (1/4" or so) hole place low in the tray to allow the water out. the pump should supply more water than that will drain.
Hope all that rambling helps. Just reply with any questions you may have.

Great post grizzman!

Thank you very much for responding with such a great answer.

Grizzman, your info and picture is great, but I do have one question. If I were using a 1.5 inch PVC overflow prevention pipe as you describe, how big should the small bottom drain hole be? 1/8"? 1/4"?

I believe I ran 1/8 or 3/16. It really depends on how much flow the pump provides into the tray. basically, if the water comes in faster then in drains from the small holes, the small hole is not too big. I suggest starting small then enlarging as needed. You don't need it to take 4 hours for the nutrients to drain. Though I suppose if it takes longer, that's less floods per day. you see the tradeoffs that you have to consider?
Also, you don't need the hole flush with the bottom. if you set it 1/8 to 1/4 off the bottom, it'll work fine and it's a lot easier to water proof.

Im having a heck of a time finding containers appropriate for this setup. If I wanted to stack one container on top of the other (reservoir on the bottom), and do the flood/drain setup suggested by grizzman, what containers can I use? If I stack them on top of the other, every container I find would stack such that only a couple of inches of height remain in the bottom container, since the top one comes in so far. Even 5 gallon buckets do this (although they are also bigger than Im looking for).
Ive searched Amazon, the container store, and everywhere and can't find a thing.
The only solution I see is to buy a setup from GH or something similar, which I'd prefer to avoid since they are 'spensive. Suggestions?

mikee77

For a container go to walmart and buy a rubbermaid "roughtneck" 18 gallon tote and a 10 or 14 gallon tote. The smaller tote will fit inside the larger one and provide the space you need for your reservoir.

Or you can buy two containers of the same size(any kind with a lid) and drill fill/drain holes in the lid of one container and in the bottom of the other.

If you have the money, botanicare trays are REALLY nice, but not really needed for what you're doing.

BTW I'm just putting this in because it seems you're still a bit green(no pun intended). But make sure you paint your container black or white. Alge could be a problem otherwise.

Also be sure to keep your reservoir highly oxygenated and under 75*F. Root rot can set in otherwise.

Mike, you could just lay a couple of 1x4's across the bottom container to keep them from stacking together. Personally, I would have the flood tray stand independent of the rez so I could easily move the rez when needed (change or adjust nutes comes to mind)
Also, in regards to Ctv2's if your container is translucent, you need to paint it. If it is opaque (as many rubbermaid containers are). you don't need to paint it. if you have to paint it, paint if black first, then white. just painting it white will not block out the sun. you paint black then white so the black blocks out sun, then white so the sun is reflected from it. (black paint absorbs heat)
Another alternative I sometimes use is to buy some spray adhesive and simply attach aluminum foil to it. That serves both purposes and works very well.
Also, aerating the rez is not so important when using ebb n flo, as the flow cycles draws air into the medium to the nutrients. There may be some benefit in aerating to prevent anearobic bacteria, but I haven't encountered that problem.
And finally, consider sterlite tubs instead of rubbermaid. They do require painting but they are a sturdier plastic. rubbermaid has a tendency to buckly outward over time when full of liquid.

If you have a farm store near you, livestock watering troughs are another sturdy option.

I used Sterilte for mine and covered each in three coats of white plastic spray paint. 100% light blockage when completed. It is very durable and has not peeled as of yet.

Here's the system build.... http://www.youtube.com/watch?v=aG8HkRmwyls

Here is a link that might be useful: My Indoor Growing Adventure

If I used a large container as you suggest, I presume this would be for multiple plants. Can I put in different types of plants into such a setup, or would that make them more disease prone?

To an extent you can combine plants. you don't really want to combine heavy feeders with light feeders. either the heavy feeders will be spindly or the light feeders will get tip burn. If you do encounter a problem, it is also more difficult to diagnose when there are multiple plants expressing it.
If you're only going to be growing a single plant, you'd probably be better of just using DWC.

Another alternative to painting your reservoir is to wrap it in "panda film" which is black on one side ane white on other. It's normally used to make a wall more reflective but works well for this too. I use white duct tape to attach. I use those clear IBC totes wrapped in it and have no problem with algae. If you paint make sure it won't chip off later on.
There are harder to find and a lot more expensive but the "Brute" brand of totes from rubbermaid are really sturdy, as well as the trash cans they sell at home depot.
I would avoid stacking the totes inside each other anyway, too much work to remove top portion with plants just to check/ adjust nutes.