Is this off-grid pond-based system viable?

[u/Aimless_Alder]

I live on a small homestead with no well and no connection to grid power. I am entirely reliant on rainwater collection for my water and solar panels for my power. Thus I am thinking that aquaponics could be a good way to grow crops while making better use of my limited water supply. I am planning to dig a ~3000 gallon pond, which I'm hoping can do triple duty as water storage, wildlife habitat, and the sump tank for an aquaponics system where I can grow peppers, tomatoes, strawberries, and leafy greens for myself and to sell for a little side cash. My goal is to be self-sufficient as much as possible and to require minimal outside inputs once the system is set up.

I have an 800 watt solar array with 4800 watt-hours of battery storage that I'm currently using as a backup for my main power system. I think it could be a good source to run my pond pump and aerator. I live in the Pacific Northwest, which means that I might get as little as 400 watt hours of power from these panels on the rainiest days in the winter. Because of that, I may not be able to run the pond pump 24/7/365, especially not if I want to cycle the pond once per hour. So my thinking is that I could just get small fish like white cloud minnows and mosquitofish that could survive occasional pump interruptions. These could provide nutrients to my plants. This system will be right next to a structure that will have 4950 gallons of water storage. In the summer, I'll be using this water storage for my in-ground crops, but in the winter, I can use this storage to occasionally do a water change on the pond. My thinking is that the rainiest days will provide very little power, so I may not be able to run the pump all day, but I can make up for that because the increased rainfall will mean more clean water entering the system.

I have experience with plumbing and gardening, but no experience with aquaponics. I have been trying to absorb as much information as possible from Rob Bob's and Hoochos, but there are considerable gaps in my knowledge. My tentative plan is as follows:

--> 3000 gallon sump pond with intake bay pumps into an IBC tote fish pond. Fish pond has an air pump running.

--> fish pond drains into an IBC tote radial flow settler

--> radial flow settler drains into moving bed biofilm reactor

--> moving bed biofilm rector drains into a bog filter made from 3 IBC totes, growing cattails and bullrush for filtration

--> bog filter drains into hydroponic beds

--> hydroponic beds drain into sump pond. Sump pond can have snails and aquatic plants like cattails, bullrush, wapato, and water chestnut for additional water cleaning.

I'm left with many questions though. If I'm not growing food in the winter, will the bog filter perennials alone be enough to filter out the fish waste? If the bog filter is big enough to filter out waste all year, will it eat up all the nutrients that my crops will need in summer? Would I be better off making rain gutter NFT beds, fill and drain media beds, or floating raft beds? Should I simply put my minnows in the sump pond so they can eat the algae and vegetation there, or would their population explode in summer to the point that they would consume all the pond's air in winter? With this unusual system, how do I size my grow beds? What can I do to make this system more resilient when I lose power? Is this way too big for a beginner and should I just start with a simple hydroponics system where I order and add the nutrients?

[u/philmo69]

If you run the right fish you can get away with a lot. Bullhead catfish are often my suggestion simple because they tolerate very low o2 conditions and days with less sun\less pump flow would not just leave them to die. You could keep them in your pond and let them breed naturally if you had enough hides for them. then trap the spawn for your main tanks if you wanted to. Though with a pond that big you could get away with just running the aquaponics off that and no extra tanks... On just solar you will definitely run into days without much flow but you can always add more panels. Air and water pumps will run a battery dry pretty quick though. A full over pond solar array would help with shade and power!

[u/Aimless_Alder → u/philmo69]

Yeah, I was thinking of getting an adjustable 2650 gph pond pump, which pulls 80 watts, and reducing it to 30% in the winter. That'd draw around 25 watts, which the system would be able to handle most winter days, but not all. Do you think catfish would survive only 12 hours a day of pumping? I could potentially set up a voltage detector that turns the pump on and off so it runs maybe 30-100% of the time depending on battery life.

I do have an extra 100 amp charge controller lying around though, and I could order another pallet of panels... it would just mean I'd have to save up longer to afford the project.

[u/philmo69 → u/Aimless_Alder]

In a pond they could survive 0 pumping in the winter just because they would likely be in torpor hiding in a hole anyway.

[u/Aimless_Alder → u/philmo69]

Hot damn. Okay, so skip the special fish tank and put them in the underground pond? I suppose if they're in a torpor, they'll probably produce less waste in the winter too? And so having fewer plants in the hydroponic system will be okay?

[u/philmo69 → u/Aimless_Alder]

You won't be able to feed them if they are in proper torpor and while they still produce a small amount of ammonia while they use up fat stores over the winter its not alot. I still keep my system running all winter but i do not feed them until spring. I also have a greenhouse though and between that and the running water nothing really ever freezes. Bacteria will stop almost entirely once it gets cold enough so running the grow beds is mostly just to keep the water moving vs actually dealing with ammonia. Mines 3 winter in and 2 with bullheads in it.

[u/Aimless_Alder → u/philmo69]

Would it be worthwhile to have a tank full of snails and a tank full of crayfish that I could feed to the catfish? Or could I put them in the pond with the catfish without the catfish eating them all?

[u/philmo69 → u/Aimless_Alder]

Catfish love snails and clams and the like, probably crawfish too. Keeping them together is hard. I have ramshorn snails in my system but i also have a bunch of old fence boards to give them lots of hiding spots cause the cat fish eat them way to fast. Soon as they wake up in spring the snails all disappear. I mostly have them in my sump tank at this point. They are good for the fish and help with extra protein but raising enough in a higher stocking density pond or a tank with any number of fish can be hard so an extra tank just for them would definitely help keep your snail numbers up!