Hello Blade,
If it were me I would probably use a system like this
http://www.hydroponicsonline.com/for...rd-system.html or this
http://www.hydroponicsonline.com/for...w-systems.html for larger plants like the cucumbers. And for lettuce I like using a setup like this
http://www.hydroponicsonline.com/for...th-system.html. I have never grown celery and don't really know how big the root system gets, and how big they get on top. But I do know there is a celery root-ball that is also sold for food, so I would guess it could probably be substantial. My first thought is using a system like
http://www.hydroponicsonline.com/for...w-systems.html but using 3 gallon buckets.
However celery is fairly cheep and I don't know if I could justify the cost of growing media to fill each bucket unless you could get many celery plants in each bucket. Because of that, I would probably find out how big the root systems get, and build a trough to grow them close together in long row, instead of individual buckets. Building the trough large enough, but not bigger than really needed to accommodate the root systems. I would also probably do the same as I did with the buckets, and fill the bottom with a good amount of rock to take up space so I wouldn't need as much growing media. and instead of coco fiber/chips I might even try experimenting with using pine shavings as the growing media. It's way cheaper than coco fiber, but still has much of the same property. However I would experiment with using the pine shavings on a smaller scale first because the quality of the source could be an issue.