I thought my aquaponics decision would be limited to which system to use, the ebb and flow, DWC, or a combination of both. If it were to be on a small scale, the decision would be fairly easy when I got to that point. But what happens when you have a costly asset already in place that could be used to grow koi? In this case it is a swimming pool on property I own that my wife and I want to move back to. It is approximately 27 feet x 14 feet, with the deepest part at 7 ft. and the shallowest about 3-1/2 feet. The bottom is rounded at the ends and the sides. From what I've read so far, it would make a pretty good koi pond.
I am studying 3 books on koi: The Ultimate Koi; The World of Koi; and A Practical Guide to Building and Maintaining a Koi Pond. If one is to keep koi, and harbors hopes of selling or showing koi, then the authors state that a minimum of 5 ft. depth is essential to the kois' health since this would allow the fish to exercise their muscles properly and maintain a proper form. That being true, in my case I would have to install the appropriate filtering system for that size pond along with all necessary protective devices. The other option would be to have the right density of fish and proportionate growout beds. Based on aquaponics research, the gallonage of the beds would be enormous, to say the least. Either way, you are looking at a major enterprise and a major undertaking. For now, it will be a small system since I still have a lot of responsibility with present endeavors.
Leila (wife) and I also discussed the possibility of a separate koi keeping and aquaponic system. So at least for now, I have to give further thought to whether or not I want a swimming pool to enjoy personally and with friends and family, demolishing the pool, or looking at creating a job for myself, whether as a business or hobby. I personally have my ideal as a system that is easy to maintain with minimum stress and expense and most importantly enjoying visual feasts (fish, plants, and aquascaping) as well as culinary ones.
I have been looking for cheap or free tanks on Craigslist and other websites, but seem to be a step late. I have decided on something around 150 gallons to start with, most probably a DWC system and 32 sq. ft. growout bed with capacity for doubling.