1) First of all, we were buying food to feed our fish. Ultimately, we wanted to be growing food for the fish ourselves. Having to buy food didn't seem very sustainable.
2) Our fish were mostly Tilapia, which are tropical fish and need warm water temperatures. They were given to us by a friend for free, which is one of the reasons why we continued to use them. Tilapia are also fine to grow in high densities, which makes them desirable for many larger aquaponics systems. We realized eventually, however, that we do not need as many fish as we were growing, so switching to a lower-density fish would still be fine for our system. We were also spending a lot of money heating the water, especially during the winter time when temperatures drop below freezing and commonly in the negatives. We have just harvested about half of our Tilapia with the ultimate plan of switching to another breed altogether.
3) aphids, aphids, aphids. The benefit of subjecting your garden to the whims of natural seasons is that many garden pests cannot survive the colder temperatures of winter. When you have a nice warm year-round environment for these pests to grow in, numbers can grow out of control. When the aphids first became a problem, their numbers were already substantial. Aphids especially loved hiding in the new, curly growths on our kale plants. It seems like I spent forever rinsing all the little crevices of kale that I harvested before I could use it to cook with. Often, we just pulled the most infested leaves out and fed them to our chickens (The chickens love the kale and the aphids equally). We tried everything we could think of to control our aphids naturally. We pulled them off the plants by hand. We used water to spray them off the plants. We bought lady bugs for the greenhouse (twice now), but the lady bugs didn't seem to want to stay around. I even spent a considerable amount of money on purchasing a parasatoid species of wasp that lays its eggs inside of aphids, thereby helping to control numbers of aphids in a population. We never noticed if the wasps had an effect on the aphid population. However, I knew I was taking a chance with these, since it was recommended that the wasps be used to control populations that were still pretty small and manageable. Ours was already out of control. We even created our own spray of garlic and pepper, which we sprayed on the plants heavily infested with aphids. This seemed to help, but the aphids came back in full force after the spray wore off. An important consideration when spraying anything on plants in an aquaponic system is the potential effects on the fish, because the spray can make its way into the water supply. This is why we didn't want to risk spraying a natural pesticide, such as neem oil on our plants. Neem oil eventually degrades and has no known negative effects when eating vegetables that have been treated with it, but we didn't want to risk the potential immediate effects on the fish.
Because of these concerns, and our desire to consolidate the indoor space to use for other needs (such as housing our rabbits), we began a new round of revisions and modifications to the greenhouse space. This what Brian is working on now. We harvested 31 fish and consolidated the rest to one tank. Brian is also working on ways to control evaporation and heat loss from our system. We are also going to harvest the remaining plants, clean the system thoroughly, and start over again with new seedlings. We are contemplating the best way to rid our system of aphids before planting anything new. The best idea so far is to clean out all the beds with hot water. Hopefully, this will kill the aphids in all potential life stages. If some return, we may be able to control the numbers with predators (such as ladybugs or parasatoid wasps) as long as we introduce them early enough to keep the populations down before they grow out of control.
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