Backyard Aquaponics
A place to discuss aquaponics

Trout.

I know a source in Southern California, but I'm not sure how far they will ship...


If you have a round pool with a flat bottom and the water that flows back in enters on an angle, most debris gradually works it's way to the center of the bottom where it is easy to have a pump or water intake. Other pool shapes are more problematic and some are not really easy or possible to self-clean (*sigh*), but if you experiment you may be able to find an area where stuff collects or suck the bottom as if it is a pool as needed.



Those beds are deeper than required for veggies. Most folks go with shallower beds to reduce gravel needed and water required(see rant). You can figure that most gravel has about 1/3 air space and that you want to fill the growbeds about once an hour, taking about 15 minutes to do it and letting it drain out for the rest of the time. Of course, this is not a hard rule and I have a system that is cycling about 3X per hour.

Most folks take water from the tank bottom to suck up solids. If that is futile and you are simply sweeping the bottom with a vacuum to occasionally transfer solids to growbeds, then the rest of the time you can take water from wherever. If you take it from the surface you might want to feed on the farthest side or it may take the fish feed before the fish can get it.

<rant>I'd love to see someone invent a low-pressure, multiple outlet valve for AP. Something that would operate on electricity to switch water from a single pump to alternately fill several growbeds without the need for astronomically expensive electrically-operated high-pressure valves. This way we would not need large volumes of water in our sumps to fill growbeds simultaneously and we would have flood-drain without the need to time and switch our pumps. And there would be an end to complex distribution system balancing, trying and trying to get all beds to fill equally from a single pump!<end of rant>

Hi Everyone,

I again talked to the AR Coop Extension guy, who has a master's in aquaculture and spends his days consulting with people who are doing or want to do aquaculture. On design, he basically said
he would set up an inexpensive tank system next to the pool to house the fish, use a water garden style pump to move water to the fish tank, and then gravity flow effluent back to the pool. He said, this would allow more control of the whole system, facilitate disease treatments, enable collection of fish waste and treatment with a bead-style filter, and facilitate harvest. Likewise, he would try to raise vegetables in a separate system to control the nutrients better and supplement with the waste water collected off the fish tank. The pool itself would essentially be a large reservoir for biological processes. In his opinion, this would keep the pool free from obstacles, facilitate cleaning, and possibly allow the occasional swim.

His rationale for a topside fish tank makes sense. That's a viable design option. But de-linking the fish and grow tanks? That doesn't make sense.

Onto fish species. He said there are no male tilapia in the region. Forget crappie because, aside from the population control issue, they are very difficult to grow, fragile, and don't do well in tank systems. Trout are grown in Arkansas (not commercially but to stock streams). Hatcheries use raceways with water from springs or clean streams. In any event, this would be a winter crop, not summer, should I go to a batch system.

He emphasized that I need to find feed-trained fish. Looks like my options are still:
1) tilapia with all the problems/benefits we've enumerated; 2) feed-trained large-mouth or hybrid striped bass; 3) feed-trained coppernose or hybrid bluegill; 4) catfish

I also talked to the people who built the pool 15 years ago and learned how to adjust input from the bottom "drain."

I'll post again later about your comments.

Thanks so much for your help,
Rebecca

How warm does your water get?
I did have a bit of a read, so may have missed it if you said a temp.

Regretfully, I don't have historical water temp data but have started a chart.
My supposition is that water temps will more or less follow the AVERAGE air
temperatures on the graph in the link below. Of course there will be time delay. And maybe a 5 or so
degree upper adjustment in winter and downward in summer due to the fact the pool is
inground. Aeration and recirculation will have an impact too.

http://www.city-data.com/city/Fayettevi ... ansas.html

To find the chart easily, search for "average temperatures" or move your scroll bar down about 40%.

Well, maybe it would: I'd need to run some numbers, but if you are warming water for tilapia to 70degF or more in the winter it would be far more efficient to only move water once a day or so. Keeping fish, aeration, bacterial conversion, and possible solids collection within a heated space could really help reduce heat loss. The plants would be in a cooler greenhouse or outdoors with water circulating from a sump. As needed, water and solids would flow from tank system to cooler growbeds.



If that is where solids would collect then taking water from there, at least occasionally, would solve most cleaning issues.


Aquaculture folks tend to be like engineers (or like most humans for that matter): they work with what they are used to. They tend toward separate systems for aeration, solids collection and removal, and ammonia conversion and are uncomfortable with the simplicity and elegance of AP.

That said, there are certainly times when it would be darned nice to be able to separate growbeds from fish for a week or two for treatment (this is a vote for separating gb and ft) and it takes a lot of salt to raise a pool from 1ppt (fine for most plants and good for fish) to 3 (or even ppt (for various ills and fine for catfish and tilapia) and then you need somewhere to dump it (this is a vote for tank over pool).

On the other hand (that's a third hand, right?), if you have fish in a pool you are going to have light stocking rates and, thus, much less chance of having stress or crowding cause disease. And tilapia will eat your algae, whether or not they grow to eating size, so they may be a good part of the ecosystem. I vote for tilapia and catfish as I've heard they are good polyculture. Just keep the tilapia in a greenhouse in winter.

In reply to your much-appreciated comments:

1) I do not intend to heat the pool. Tilapia--if that's the chosen breed--would be only a summer crop. There is, however, a possibility of using season extenders like a straw bale greenhouse (probably separate from the pool) or pool cover of some sort. Sadly, I don't have enough southern roof nearby for the black pipe idea. But I do for a solar shower!

2) Per TNLynx's fish to grow bed ratio, if I aim for 50# of fish, I'll need about 200 gallons of grow bed. I am still concerned about the concentration of nutrients in the cement pond. I don't see how a lot of water that is very dilute with nutrients will fertilize plants in the same way a richer mix would. To get water rich enough to feed plants, it's likely to be nasty for fish.

3) The livestock tanks (metal or plastic) are appealing because they are readily available with outlet fittings near the bottom, and not too expensive. A 6' round tank is $170 new. This same tank filled with 1 foot of gravel should hold 200 gallons of grow bed, if I'm following the calculations correctly. However, I understand the optimal grow bed depth is 12". That 1' differential means I'll need to grow seedlings larger before transplanting and/or increase the gravel bed depth. Around here, it shouldn't be too hard or expensive to get small creek rocks as a medium.

4) Hydrophilia, I think the tilapia/catfish idea is certainly worth entertaining. Would you put them together in a topside tank, since you voted for that?

Finally, the coop extension guy said that, for every person who succeeds in such an enterprise, there are 20 who fail. Do folks agree with that assessment?

Thanks again, Rebecca

I see it differently. The success of the plants depends on the amt of nutrients that they can absorb which depends on concentration, so you need the same concentration whether it comes from a large pool or a small tank. The difference is in how fast nutrients would build up (or get removed once plants start really growing). The only issue I can see is, perhaps, in circulation and aeration or stagnation, but I think that as long as you have the right amt of growbed to fish you will be fine.


Or pea gravel, especially some that has been reasonably washed already so you don't need to break your back, even though that is traditional.


Pool (seasonally) or tank. As I mentioned, tilapia do a great job of eating algae, even scraping it down to glass in my aquarium while it grows in great mats with other fish alone.


Commercial or hobby? As a hobby it is fun and you get tasty fish and veggies and, I think, it is often easier than gardening as you avoid digging and most weeding. Also things that often taste bitter are far more mild, even radishes are simply crunchy treats with a mild radish flavor. If you like gardening, running water, and fish this is a high win situation counting fresh food at market price and labor for free. Commercially it is far more problematic as you are dealing with a whole different set of cost/benefits. Take a look at the commercial systems section for more....

You could build a small dome greenhouse around & over the pool. Solar heat in Arkansas is great and the winters are mild, so solar is a real option. Natural gas is also cheap in Arkansas, so a little heat would be affordable. If you can;t get your water to stay consistently in the upper 70's to 80's, tilapia are likely not a good choice.

If you go with tilapia, you don't need all male fish. I've been experimenting with cages, thank to a tip form Mike Sipe. As long as the females can't find a flat surface to lay eggs on, they can't make fertilized eggs. Put the fish in large cages and put the cages in the pool. Easy harvest that way too. You would not need a separate tank system.

A pool sand filter make a great filter for tilapia. You can back-wash it every day into the grow beds. Most setups put a skimmer in the center of the pool with a pipe in a pipe. Suction is taken off the bottom, but it is forced to the overflow of the inner pipe at the top.

After tip from someone in this forum, I'm checking out hybrid bluegill. This is a cross between sunfish and bluegill that looks promising.

See http://www.ksuaquaculture.org/Species/B ... Hybrid.htm

Definitely look into making some cages for the tilapia if you do go that way then. I've made some using PVC pipes and netting, pretty easy to do. The black pipe does not have to be on the roof though, I've got my aquarium system heater is just a few loops of black pipe laying on the ground.


As noted by others, it doesn't really matter how much water there is so long as the amount of plants, filtration and amount of fish are in balance. It is really the nitrate that the plants use, the ammonia and nitrite that are immediately nasty to fish are what is converted by the bio-filter or bacteria in the gravel beds. A functioning AP system usually has far nicer water than even the best Aquaculture facilities. Don't worry this is something that many people have trouble with but the truth is, more water does not cause the system to be too dilute to work. It just takes longer for the system to get up to it's balance.


Do be careful of using metal tanks unless they are aqualined since galvanized tanks can cause problems with fish any metal other than stainless steel could be a problem if used as a growbed or fish tank.
So how many gallons do these tanks hold? It is ok to have deeper gravel, there are people out there with grow beds that are 2 or even 3 feet deep. 12 inches deep is only a handy standard depth. so if by filling that same tank to 2 feet deep would give you 400 gallons of grow bed, you could support more fish using the same $170 tank. It just means you need more gravel to fill it but having extra deep grow beds is not a bad thing. Even if you did only fill the tank to 12" deep, that does not mean the the seedlings have to be over 12" tall before being in the bed, they won't die because they can't see over the side. Just means that any little seedling right up against the south rim will be stretching for light.


sounds like the coop extension guy must think you are planning a commercial enterprise. If you are planning a commercial enterprise, then I suspect that the extension guy is right. If he and you are both talking about backyard Aquaponics for home food and hobby reasons, then I totally disagree! I think my backyard Aquaponic enterprise for home food production and garden hobby enjoyment has been very successful and my big system isn't even a year old. There has been some discussion about what constitutes successful or economic gains from an AP system. Does it mean is my AP system not only paying for it's self, the fish, the feed, the electricity, the seeds, while providing all the food and fiber needs of the household, and paying the mortgage as well as providing my family income? Well no not for me. Success for me is that we are eating meals from the AP system regularly while I enjoy the hobby.

What are your goals in your AP enterprise?

TCL as I would expect, you have again hit the nail on the head

Quote - What are your goals in your AP enterprise?

This is the question all of us should have asked ourselves.

Anyone who thinks it would be easy (via solar means) or cheap (via gas) to heat an inground pool probably hasn't been to this neck of the woods or checked out the temperature link I posted above. This morning, the pool temp at 2' down was 40 degrees. Brrrr.

It's too bad fish don't always float to the top when they die. That would facilitate tilapia harvest from cold exposure. And it might be a relatively pain-free way for them to die.

A guy at a natural pond nursery around here said they would swarm to feed and I could net them easily that way.

Speaking of feed, have any of you looked into raising daphnia? If not, check this out. All fish eat them:
http://www.aquariumfish.com/aquariumfis ... 88&search=

(My initial goals are, first, to achieve a stable system and, second, to have fun while supplying two households with fish/vegies.)

As Einstein said, it is all relative. I live in Upstate NY. I can break more than even. Your temperatures are milder, and you gas prices are an order of magnitude cheaper. My son lives in Mt. Magazine, so I'm not a stranger to the area. Point is, with proper construction, it is possible to be profitable with tilapia where you are. Check out the AG extension and find other tilapia farmers in Arkansas. Pick their brains. Good folks there.

Hmmm seems rainbow trout would love 40f = 4.4c and with a max aver. of 80f = 26c will still be fine
without using external energies to heat water.

Might work, if the water is shaded in summer. Don't trout have trouble above 70degF (20degC)? Sure would be nice to have fish that do well year-round.