What really prompted this project was the fact I was getting very tired of the fire ants getting into my raised beds. After losing much of my crops to ants, I decided I was going to grow in water via hydroponics. Then, I was able to convince my wife to let me put a fish tank on the deck for another aquaponics build - so it was on ;)
Thanks to the help of my son, all of the 6" screws were taken out of these timbers, we cut them to size and ultimately built a smaller version for the tank and used some of the pieces for legs and supports on the grow bed. It is worth noting that we were able to reuse most of the screws that came out of the timbers as well so I did not have to buy any.
The size of my grow bed and the size of my tank were based on mathematical calculations made by me based on the amount of pond liner I had available to me. I bought the kit (see picture) on Craigslist for $25 - it was still brand new in the box. The liner was 8x10 so I had to figure on how much I could use of this. I elected to build a tank that was 2x7 x18" deep and grow bed was 1x7 x1' deep for optimal root space. Of course, if you are using a different size liner, just keep in mind that your depth will take off length and width from ALL sides (if you go 1' deep, you need to take off 2' from length and width, which works out to 1' all the way around)