Hi Im in the process of designing my indoor aquaponics setup. I will have 4x8' of ebb+flow tray in my system. My question is about the depth of these e+f trays. I have read about the suggested 12" depth and the 3 different layers within the grow bed. I would like to build a 12" deep tray out of wood lined with pond liner, but i am on an extremely limited budget. My other alternative is that i used to be a big hydroponics grower and i have hydro e+f trays that i already own, but they are only 6" deep. I am wondering if this shallow tray will be ok or should i really try to get the few $100 together to build the 12" deep trays myself? The reason i am leaning towards 6" beds is that i already own them (money savings) and i am only planning on growing herbs or salad greens (mostly basil) which do not need as much root space as tomatoes or cucumbers. What do all you AQ growers think? Also, if i increased my grow tray depth from 6" to 12" would i be able to grow more fish in my system even with the same amount of plants?
6" deep trays can work but yes you will be limited in your filtration. I would suggest that the 6" deep beds would probably be easier to flood and drain by timer since I've found the shallower beds to be challenging to get a siphon working well in them.
Use what you have for now, I expect you will be planning ways to expand in the future. For this first system, you will want to keep your fish stocking minimal anyway so you can probably go ahead and use the 6" trays. Aquaponics is addictive and most people are already designing their future systems even before their first system is fully cycled up.
I would tell some one not to buy the shallow tray if they were shopping for aquaponics but seeing as you already own it, I would say use it. At a later date you might convert them over for growing something like water chestnuts or water cress or something.