grapes in the ground need to have a PH around 5.5 to 7. their are other posts that i found and looks as though grapes have been grown in aquaponic setups. if i was to grow a grape vine in an aquaponics i would place the plant where it woulg get the least ammount of nitrogen as to much nitrogen can cause problems. but their is nothig that i learned in my vineyard class about growing grapes without soil! so i guess you could just give it a go! the book i had to buy for the class is called 'THE GRAPE GROWER" by Lon Rombough. you may want to get it depending how far you are willing to go! if you are looking to experiment with will it work then you dont need the boook but if your looking into doing something like make a little wine or grape juice or have good eddeble cluster fo grapes you may want to at least think about getting the book!
oh, it will take about 2-3yr before you'll get eddible fruit from the vine and you may wont to look up how to properly prune the vine to get the best results!
but like i allready stated i dont know how it will do in AP setup so at the verry least you could give it a try!
I would suggest growing them hydroponically first and reporting your results. This is because grapes haven't really been tried by most aquapons, so good information would be nice. A hydroponic environment can be controlled (at least with a nutrient solution) and can provide an approximation for other bio-ponic techniques, including aquaponics. Although, you could just stick a vine/seed in their and try it. It will probably yield good results.
When we get a particularly wet summer/fall, my grapes will start to split while still on the vine. This is bad for harvest-able yield and sugar content/taste. I wonder how that will play out in hydro or AP? Maybe it wont be an issue, try it out.