Aquaponic Gardening

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Hi!

Introducing my first aquaponic system which is under construction.

It will be a flood-and-drain system, with the grow bed raised to waist level, and draining back into the fish tank. I haven't planned a sump or reserve reservoir, just keep it simple: one fish tank, one grow bed. The volume of water in the fish tank is almost the same as the volume of gravel in the grow bed.

Here are some pictures. Let's start with the fish: 10 Mozambique tilapia, currently indoors, fertilizing my pot plants.

Next, here's my greenhouse, which I will need to move, because it's placed too shady by the previous owners of this house. I hope to move it in April, if I get a whole bunch of friends to come here and help me carry it! It's only 10 square metres (107 square feet).

Next is my fish tank, which is 300 litres (79 gallons), standing on edge in a shed. I got it for free, because it has a leak. Due to a misconstruction in the first place, it will always leak, whatever you try, but the leak is so small that I'll lose no more water than through evaporation. It's just not a tank for indoors.

Here's my grow bed that I'm currently building. I'm re-using some recycled-plastic boards as the sides. The bottom is a really hard and heavy board that I found in a waste container. I will line this with some pond liner, and plan to make a home made bell siphon to empty it.

Finally, this is crushed lava gravel that I have left over from a roof garden that I rebuilt. I'll have to wait for the snow to melt before I can check if I have enough of it, or if I'll have to make a mixture of this and Leca (=Hydroton), or ordinary gravel.

I plan to grow cucumbers, tomatoes, basil, lettuce, and maybe wild strawberries in it this first year.

If my plan holds up, I'll have this system up and running in May this year! However, work will pile up on me as soon as spring comes, so I try to prepare all I can while it's still winter. There's always a risk that I won't make it this year, but let's hope!

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That fish tank hopefully doesn't have any metal actually in contact with the fish water right?  Or if it does please tell me that it's high quality stainless steel.  Any other metal would be ill advised for fish water contact.

The grow bed, it's really hard to see the scale of the thing in that picture.  I can't tell if it's totally huge or made with legos.

Cool use of existing materials though.

Tell me more about what kinds of metal are dangerous to fish. Pumps have metal parts, right? I've even seen the recommendation somewhere to have rusty nails or iron filings to add trace elements to the system.

This fish tank has been used for fish before, though not by me, so I don't worry too much. The bottom inside is covered with silicon - I don't know if that's the word you use, but the stuff you glue aquariums with. Since there's a leak, obviously there can also be some metal in contact with water. But what's dangerous for fish and what isn't?

The grow bed is approximately 2 meters x 60 cm x 30 cm (6½ feet x 2 feet x 1 foot deep). That adds up to 335 litres (88 gallons). I converted wrong before: the fish tank is 79 gallons.


TCLynx said:

That fish tank hopefully doesn't have any metal actually in contact with the fish water right?  Or if it does please tell me that it's high quality stainless steel.  Any other metal would be ill advised for fish water contact.

The grow bed, it's really hard to see the scale of the thing in that picture.  I can't tell if it's totally huge or made with legos.

Cool use of existing materials though.

looks like a nice start. With a glass based tank, I'd be a bit leery about the potential for massive algae growth.

You can use some window film to block out light or throw a pleco in there to clean the tank for you.Don't know what material your using for GB, looks cool though.

Ok so if the sides of that tank are glass and the bottom coated with silicone then it's probably safe.

Most metals are not good for aquaponics because they will leach things like copper, zinc, nickle, led etc that we don't want in or food or that can build up to dangerous levels and kill fish.  As to iron, well some amount of iron is needed for plants and that can be a bit higher and still be safe for fish to a point.  However, I wouldn't recommend using iron pipes since you don't want your plumbing rusting out and aquaponic water will cause iron to rust faster than normal and galvanized coating will leach too much zinc into the water for fish safety.

I do actually have an alternative fish tank, one of those blue big barrels.

The fish tank is the one on the right. At first I intended to follow Travis Hughes "barrel-ponics" instructions, But then I changed location for the system, and decided to change other things too. But the barrel holds only 200 litres (50 gal), and will probably not be that full. Would it not be too small in relation to the grow bed?

Good to know to avoid metal plumbing.

Will the tilapia not try to eat a pleco?

My Pleco has been in the tank for two months Louise, with no fish on fish violence. The pleco has a armored exterior and is twice the size of my tilapia.During the day he just hangs out on the bottom or sticks to the sides of the tank.At night he gets really active and the tilapia generally stay out of his way.I think tilapia will try to eat anything that fits in their mouth...just make sure your pleco doesn't .LOL

Tilapia fry and small fingerlings have an immense protein hunger and when they are small they will eat anything they can and try to eat somethings they can't.  When the tilapia get bigger they are less and less likely to eat other fish and any violence with larger fish is usually due to breeding behavior or females becoming aggressive/protective before they release fry from their mouths.

I've never much liked the barrels on their side sort of fish tanks because I always had trouble seeing the fish in them.  But it will probably still come in handing as a water holding tank for something or other like prepping water before top up and stuff like that.

Here's my mini indoor test system. I built a home made bell siphon, after instructions I found on youtube.

Here are some details: There's an outer bottle with the bottom cut out, and slits to let the water in and air out down the bottom. The inner bottle is cut so it's just a funnel, attached by the bottleneck on a piece of green hose. That is in turn attached on a plastic fitting for making a hole through boats. Under the growbed, I put in another piece of hose that is narrower, as the downspout. See the photos below:

When I put it up like this in the bathroom, I could experiment with how much flow the pump gives (it is adjustable, intended for ornamental ponds), until the ebb and flow cycle took about one hour. Worked perfectly. However, once I put it into the indoor fish tank, the pump flow turned out not to be constant. Maybe debris from the fish gets into it and slows it down. The trouble is that the system keeps going into an equilibrium where the speed of the water going out of the siphon equals the speed of pumped water. Mostly that happens with the water level in the growbed very low. Little radish seedlings are getting drought symptoms.

Here the system is with plants in, on top of the fish tank:I think I need a siphon discussion, to get this sorted out.

Ok, getting serious now. I've spent all spare time the past 10 days on this. Now almost done, I have some problems to solve:

1:The LECA (Hydroton) rises like a bread dough when I add water to the grow bed. Since other people use this stuff, I assume it stops doing this - when? It looks hydrofobic on the surface, that is, it looks dry after being sprayed with water.

2: My sump tank can not hold all the volume from the fully drained grow bed, though some of you reported that the water would be about 40-50% of the total grow bed volume when there was media in. This does not seem to be the case, at least not with the LECA floating like it did today.

3: My pump! Blah! The float is really difficult to use to adjust both when to start pumping and when to stop, so it doesn't do what I want it to at all. It seems really erratic and unreliable, from my one day's experimenting. Here's how it looks:I had a hard time finding a pipe fitting that fitted it, so I ended up using a 32 mm wide hard plastic pipe (big black arch seen in the top photo), because I found fittings for that. But it means the pump is extremely fast, and even though I have two overflow pipes from the fish tank, for security, it pumps much faster than they can empty. The overflows are 32 mm wide too, so with two, that's twice that of the single pipe entering the system, but draining much slower, just with gravity.So, I had expected to start cycling today, but I think I need another pump first. Or find a way to make the float reliable and a fitting with a smaller pipe/hose.

Any solutions for me?

Forgot to write that I did change my original plan somewhat, and am now doing CHIFT PIST. And, yes, my original plan was also delayed by just one year... The good news was that it was delayed by me earning money. :)

We have three beds, one of just hydroton and two that are two layers (bottom, lava rock and top, hydroton). The bed of just hydroton did give up issues with rising with the water level so that we had to weigh down the siphon guard to prevent balls from entering the drain.  the other two beds don't rise.  We have found though that as the plants have grown, the clay balls aren't rising as much.  I noticed that you mentioned you had some lava rock.  You might want to consider a layer on the bottom of your grow bed.

 

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