you can use vinegar and baking soda to adjust pH, but it's my understanding they won't hold the pH in that range for very long. So you'll just have to adjust it more frequently.

The only problem I immediately see in your EnF drain dripping into your tamato is the watering intervals. I would think you'd water a drip system more often than an EnF system.

If the EnF system, and the drip system, both utilize the same clay balls, and coco coir setup in the pots, will the pots react differently? That's why I thought if I gave the buckets the full stream out of two 5 or 6 gallon trays I might have to divert some of the flow-back away from the buckets. Otherwise, they would get much more nutrient over a longer period.
I guess my biggest problem right now, is the fact that I ignored the temperature tolerance of some of my plants. The cucumbers, and okra are looking good to great. I think the lettuce will do well too. I have two tomato plants that are looking beat. I have other tomato seedlings that are reaching 10" now, and are growing fast. They came from a friend. I asked where she got the seeds, or what kind of tomato it is and she told me that it was big and tasted good. I'm going to take a couple of them and see how they hold up to being rinsed and converted to hydro They don't seam to mind the heat. The only way I could go wrong is if someone tells me that once they get fruit, they won't last in the heat like when they wee young.

Even using the same growing medium in both a flood and drain as well as in a drip system, the roots in the drip will get more air/oxygen than in the flood and drain system (assuming the flow rate is equal). While the flood and drain system is flooded (pump on) the roots are completely submerged, and are only getting oxygen from what's in the water (until it drains). In a drip system, there is still generally a lot of air still in the root zone while water drips down through it. But just because you are using the same growing medium in both systems, that dosen't mean that the the moisture retention will be the same in both systems.

Two other variables are the amount of growing medium (the overall volume of growing medium). As an example a five gallon bucket filled with growing medium will hold much more moisture than a 3 inch basket filled with the same growing medium, thus the 3 inch basket will need more frequent watering. The other major factor is the size of the plants, a large tomato plant will suck up a lot more moisture, than a small lettuce or strawberry plant will, even if they both have the same volume of growing medium. So the large plant/s will need more frequent watering.

My rule of thumb is to try and make things adjustable. That way you can see how the plants respond and adjust to their needs accordingly. One way to adjust water flow is with a ball cock valve, it can be opened or closed according to the water flow needed through it.

P.S.
One thing that's important with tomato's is even watering. The fruit can tend to crack if the roots are subject to moist then dryer conditions between watering cycles. So you'll want to keep them evenly moist.