Backyard Aquaponics
A place to discuss aquaponics

I have been a stalker on several forums for some time now. I have just not taken the time to do a full write up of my story. I hate to say it but I am now setting out my story in the hope that I get some ideas to solve some of the problems I have encountered. I live in a small town, Homer, in Alaska and have been very involved in my community as a nurse midwife. I live in a community with a strong desire to have fresh, organic produce. We have the highest number of high tunnels of any zip code in the US. We have a fabulous Farmers Market in the summer. I have been saying for years that we really need to be able to provide local, fresh greens to the community but no one had done that. I was playing around with hydroponic growing in the house. I successfully grew lettuce, basil and tomatoes to eat each year. A few years ago, a friend gave me Sylvia Bernstein's book to read. I got really excited because I really felt that aquaponics could solve some of the problems that I would have with hydroponics. So I began to do a lot of research and we went to visit some farms that were already running. So Alaska Aquaponics was born. We built a 22 x 36 foot green house with an insulated foundation and triple wall polycarbinate. I have done a lot of research about running the greenhouse, fish, plants and marketing. I feel like this small greenhouse will hopefully be a prototype for a larger system if it all works as planned. At the very least right now I can provide greens to the local health food store and have a small CSA and we get to eat REALLY well.
The system
I started with a 1000 gallon tank for a fish tank, I usually keep about 800 gallons in it. It is tall so to make the smallest foot print possible. Water runs through a SLO by gravity to 3 4x8 foot grow beds with hydrocorn. My fabulous bell siphons fire about 4 times an hour. The water then flows by gravity to a 8x24 foot raft bed. The one pump in the system sends the water back to the tank with continuous flow. I grow produce that I can cut and come again in the grow beds and the rafts hold lettuce, bak choi, mustard greens and other greens. I must say - it is all very beautiful and brilliant! I am very proud of how well it works. I have room to try some of Nate's towers and Vlad's dual rooting ideas and maybe some small wicking beds. I love to experiment and tinker. I set up aerators for the raft bed and for the fish tank. I just got some LED lights to try out for this winter. I heat with natural gas and am set up to do a climate battery. I also have hot water pipes run through the floor so we will set that up eventually too.
I started with some goldfish that I already had and in early March we added a couple hundred small Koi. I had cycled the system and had Nitrates all through February but once the plants really started to grow I never saw Nitrates again (or ammonia). I decided I needed some more Koi once I started running the rafts. So I added another 125 from the same source.

I had some great months with happy fish and plants but the end of June I started to get a dead fish every few days. They were unmarked and looked fine. Some were bigger and some were smaller. My water tested fine. My Ph was consistently 7.8 though I expected it would go down.
Water temperature would hover right at 65 degrees. I soon realized that these were not just random deaths. I was getting 1 a day and by mid July, several a day. Still not marked. They were flashing (jumping) some and sick ones were resting on the bottom of the tank. I tried just taking those out and I tried salting the whole system (several times). I actually looked at them under a microscope to try to identify the culprit but saw nothing. In August they began showing what I think was a secondary bacterial or fungal infection with lesions and fin rot. During this time my pH actually did drop to almost 6 and I did buffer it up thinking the fish might be less stressed if it was higher so I used oyster shells to do that. Meanwhile, I have lost a lot of fish and was not feeding since they were not eating well and eating can stress sick fish. So now my plants start to suffer from lack of nutrient. I have added some worm tea and maxicrop to try to help them. My worms in my grow beds seem really healthy and seem to be multiplying.

I removed my fish from the system entirely and treated the with many different treatments. Tetracycline, more salt, Melafix (teatree) and finally malachite green and formalin (ugh). They just continue to be sick. I set them up with their own grow bed (for filtration) and keep them completely separated. I thought it was just them so I gave it a few days and put feeder goldfish in the system. Now, I know they are not the strongest or healthiest but after 3 weeks in there - they have started to die too. No sign of any of the lesions - they look fine but I pulled 10 dead out today. I am sending some fish off to the State Lab tomorrow to see if they can help me figure out what is wrong.

So I am looking for any other ideas, what could be causing this? What can I do to stop it (even if I don't know what causes it)? If I need to take fish out of my system, how long and what can I use for nutrient that would allow my to go back to fish eventually? I sell some produce so I don't think peeponics will work. Any ideas or thoughts? I am still really excited about this but need to get through this difficulty!

I don't no a hell of a lot but if your fish were fine for a while then look at your pipe work etc it could be a chemical leaching slowly into system only guessing

Are there any physical symptoms on the fish at all?
Your project sounds great, shame to hear you've had this hiccup.
Hope it all pans out.

I guess it's also worth asking if there is any copper or galvanised metals used in the system?

When you removed the koi from the main system and put them into a separate tank, did you use water from the main system in their new tank? (Trying to work out if it's a disease organism or water conditions affecting them).

I have all PVC pipes, no metal at all in the system. The grow beds, sumps and raft all have dura Skrim liner. I don't think I have any enemies who would put something bad in my system. I have never found any wild animals or birds in the greenhouse. As for the fish, the little guys that are dying look fine except a small red dot in the eye. The big/older Koi are now really messed up with rotting fins, lesions and mouth rot. I still think that may be secondary but I have not been able to treat that either.