My commercial system plan

[adamtheha]

Hello everyone, I though I would post the tentative plan for my commercial system for some input.
I live in Southern Alberta, Canada, where winters are harsh, summer is short, but I have a HUGE parcel of land to work with, and a rural setting, so pretty much anything I want to do is good to go. No permits, fees, inspections (except the fish culture license).
Because of the climate, I have decided to culture Arctic Char, which is a fairly easy cold-tolerant species, and that will eliminate the need to heat the water, which would quickly become unsustainable in my system. They actually prefer the water around 6-12 degree C, which is quite easy to maintain, especially in the system I am building.
I have already dug a 35 x 12 foot hole in the ground, about 6 feet down, and piled the dirt on the north side of the hole. My intention is to create a below-ground greenhouse, that will take advantage of the amazing thermal-retaining abilities of moist earth, and allow me to access ground heat. I plan on running some water pipes through the ground to capture and store heat, which would then be released at night. I might do air instead of water, I haven't decided yet.
I have read of greenhouse systems in Nebraska and other cold places using this technique to keep a greenhouse above freezing, even when the outside temp is -30 C (or F). Since this is a proven technology, I'm certain it should work.
I plan to place the fish culture "zone" deeper into the ground, and use gravity to drain the water from the growbeds, back to the fish tank. This would be an ebb/flow design with solids removal at several points along the water path.

Some questions:
1. Has anyone on this forum ever tried using a below ground greenhouse for aquaponics? How well did/does it work?
2. Will Arctic Char do ok eating duckweed? I plan to make duckweed my first "crop" and try feeding it back as a supplemental feed. My eventual goal is to eliminate purchased feed, and I am willing to accept a lower growth rate as a result. What else could I feed to Arctic Char, or possibly Trout?

Problems I am aware of:
1. We are off grid, and plan to stay off. I will have to majorly beef up my RE system to support pumps and aerator devices. In the darkest part of winter, I will be scaling the system back to a very minimal level, perhaps cutting back to just some fry growing out for spring.
2. The hole I have dug is cutting into our water table, and water infiltration is a problem. I will create a spot to pump the water out, and hopefully store it above ground for my "normal" garden/berry bushes etc. The water is poor quality, but perhaps it could be added to the fish tank, if I sand filter the crap out of it?
3. Because we are so far north, we get much less winter sunlight, which means much reduced plant growth, and less uptake of fish waste. I will have to balance my fish population to counteract that concern.

My goal is to build this into a revenue stream of $15-20k per year. That could take several years, and I'm ok with that. I've got cattle, berries, and apple trees that should be producing by then, and perhaps I can quit my job and do what I truly love full time!

Any CONSTRUCTIVE criticism would be welcome. Don't tell me that the below ground greenhouse won't work, it's been done successfully already. Everything else is open for critique.

[Damon]

First and foremost, do not, under any circumstances, use duckweed in, around, or within 1000000 miles of your system. 1. once fish are trained to eat a specific food, it's darn near impossible to train them to else something else. 2. duckweed does sound attractive, it grows like a weed, and yes if you train your fish to eat it, they will, but they will also suffer. all of the information on duckweed being an applicable source of fish feed is bloated. it's like having your fish live off of tofu, instead of steak. your fish will live shorter lives, be under weight, and in all likelihood will refuse to reproduce du to lack of protein. you will only get a 25% protein to weight ration if you measure your duckweed in dry weight. and since you wont be feeding your fish dry duckweed, mainly because at that point it's just dust and the fish WILL NOT EAT IT, it's just another bloated figure. 3. adding ground water, filtered or not, into your system is risky. what ever is in your ground water, will be introduced to your fish, even the micro-toxins that don't readily filter out. you'd be better off just keeping that water separate, and mixing it with the fish emulsion water right before you water your ground plants. 4. some sun rays do make it through the clouds. i have a fiend that lives in Waimea Hawaii, and they live on the cloudy rainy part of the big island, only getting good amounts of sunlight for about 2-3 solid days a week. being in canada you are looking at seasonal setbacks, which you are already expecting, your biggest problem will be keeping the plants at 60-65 degrees F, (in you're growing lettuce) and keeping your fish at their happy baby making temp. on a side note which you did not mention, the biggest thing most people completely skip over while planning their commercial operation is the space required for seeding tables. putting your plant seeds directly into your system will result in a 70% fail rate, or at least those were my numbers under the best weather conditions (i was in hawaii, so the weather was more or less perfect.) putting your seeds into seeding trays for the first few weeks and letting them get to about half an inch tall in your choice of growing medium is more than enough time for the root system to grow to a stable point. what we say when putting the seeds straight into the system was the lettuce would make it to about 3 inches tall before they would suffer from root rot. the roots seem to need a semi-moist start, then you can plop them into the water. just like any plant, too much water too fast is just as bad as no water water at all.

[GaryD]

Hi Damon,

First and foremost, do not, under any circumstances, use duckweed in, around, or within 1000000 miles of your system.

That depends entirely on your circumstances.

In a commercial raft system, I might agree, however, in a backyard flood and drain system.....growing (for example) jade perch (which like to eat duckweed) it's a different matter entirely.

Gary

[Damon]

with growing duck weed we had problems of controlling its growth. Aquaponic systems are packed with nutrients, and when you add that to the fact that duck weed is in fact a weed and grows like on under normal circumstances... it lead to disaster on the farm i managed on more than one occasion... fish may enjoy eating it while it is fresh, but if a bad piece is allowed to survive and multiply it will continue to do so... and with multiplication you'll have the rotting sludge at the bottom of your fish tanks grow and grow and grow... until one day you walk up to your breeding tank and all of your fish are belly up because the whole tank went anaerobic because of the massive amounts of decaying duck weed. in dealing with fish tanks, no matter what kind of system you are running, you are going to have standing water for your fish to live in... and it's only a matter of time before a tiny little microscopic piece of duck weed makes it's way into you fish tank and kills the all with the quickness.... trust me... happened to 2 of our 4 trough systems, 2 of our breeding tanks, and a separate system 20 yards away, all of which went anaerobic and died. cost us about $70k, not mentioning the hours it takes to drain the entire system, bleach it, rinse it, dry it, refill it, degas the chlorine, waiting for the nutrient levels to balance, and starting over... in my opinion, speaking from experience... alot of experience... its better to stay away from duckweed, no matter what you think may or may not eat it.

[Damon]

i mean the thought of free fish food is just a down right sexy idea... but when you hear about all of the consequences of using the stuff... most people would rather be safe than sorry.

[fishfood]

Do you mean to that i better pull my system that has been running successfully on a mixture of duckweed and fish pellets for the last 4 years down and start again
as Gary said depends on your system

[Damon]

laws of statistics and Murphy's laws... if it hasn't happened yet, eventually it will. if it can happen, it will happen... to an extent you're correct in saying it depends on the system... shifting pH's and varying levels of oxygen my be preventing your system from being taken over by the duckweed, and if you want to play with fire, by all means, play away. but for the sake of efficiency, safety, and the ease of use dealing with the floating raft system, i'd keep clear of the green devil.

[GaryD]

Hi Damon,

When it comes to duckweed, I think you have to acknowledge the difference between a commercial raft system and backyard flood and drain ones.

The climate in Hawaii.....where growing conditions are as close to perfect as you're going to get...is also a factor.

Gary

[Damon]

that's for sure. the duck we that infested didn't just grow on the surface of the water, in one of the tanks that was for personal use we let it grow for a few weeks just to see how bad it could get... turns out the actually sprouted little stems and grew upwards due to sunlight competition.

ebb and flow systems would handle the duckweed better, limiting the growing conditions.

different strokes for different folks.

[RMAN]

I would not listen to anything Damon has to say. I have read through countless threads and if there is one thing that sticks out, it is Damon speaking as if his word is law. There are so many incorrect assumptions and postulations throughout his posts that it's scary. Reading through this thread just puts it over the edge. The spreading of mis-information is about the biggest problem I see in aquaponics and this name Damon just keeps on popping up. Seriously, for the good of the world...stop your madness and keep your incorrect information to yourself. Maybe they can tag you with a "buyer beware" clause.