Introduction: Aquaponics (Growing Plants With Fish Poo)
I've been fascinated by Hydroponics for years. When it finally came time to play around with one, I found out about Aquaponics - a sort of symbiotic relationship between the plants and the fish. The fish provide food for the plants, and the plants clean the water for the fish. Let's see how it works!
Please bear with me, this is my first Instructable :)
Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.
Step 1: Gather Materials
I did quite a bit of reading up on Aquaponics systems before deciding on this system design. You may want to look around for ideas on how to proceed.
(1) Plastic tote (for plants) $10 at the grocery store
(1) Bulkhead fitting for drain $12 at a local hardware store
(6) ft 3/8" Polyflo tubing $10 at Lowes
Polyflo fittings (all push to connect, or Insta-Tube) 3/8":
(2) 90deg elbow $4
(1) Ball valve $6
(1) Submersible Aquarium Pump* $40 at local Aquarium store (see note below)
(1) 10 gallon Aquarium $free! I've had it since I was 10 - check Craigslist
(1) Bag of Hydroton grow media $32 at a local garden shop
(6) inches of 2" PVC pipe $? This was scrap
(1) 2" PVC Pipe Cap $? Got it from my Dad
(16) inches of 1/2 PVC pipe $ Also from Dad
(1) Tube Aquarium Safe Caulking $10 at local Aquarium store.
DO NOT USE NORMAL CAULKING, IT WILL KILL YOUR FISH (which is bad)
(1) bunch of shiney rocks
(1) Something to put your fishtank on
(1) Shelf about 3-4 feet above the fish tank
(10) gallons of water
(some) Fish I'll get to that bit later :)
- Wood Saw
- Cordless Drill
- Drill bits
- Hair Drier
- A small file
- A Sharpie marker
Notes on the pump:
Make sure it can pump water up to where your grow bed will be - the higher you pump the water, the slower the flow rate. My pump is rated for 160gph(gallons per hour) and it works pretty well pumping water 3 feet vertically. Talk to your local Aquarium guy if you have questions.
Fish don't like copper or Brass. Don't use them anywhere for anything. Use plastic. Seriously.
Step 2: Connect Polyflo Tubing to the Pump
The pump that I purchased didn't have a good method for attaching a pipe or a tube to its discharge, so I got a bit creative.
Using the hairdrier, I heated the end of about 3 feet of the polyflo tube until it was soft all around.
I used a pen to flare the end of it until it was large enough to slip over the discharge of the pump.
This took a while, and a bunch of patience.
I didn't end up needing the caulking for this bit, but you may need to to make a nice seal. For me, when the tube cooled, it shrank a bit and made a nice seal.
Step 3: Install Drain on the Grow Tub
This is the bit that took the most research - how do I make a system that is simple and reliable?
Having worked in a factory before, I know that level sensors and valves and timers can find all of these great and interesting ways to fail and make huge messes.
The solution to this is the Bell Siphon. It is incredibly simple, and incredibly reliable. Perfect!
For a neat animation on how they work, check out this link:
For this system, the bell siphon consists of:
- The standpipe attached to the drain hole on the Grow Tub.
- The 2" pipe and cap acting as a "bell"
First, the toilet bowl assembly needs to be cut apart so that we are left with a 4" pipe on the end of the Bulkhead Fitting (a bulkhead fitting is a fitting that is designed to attach a pipe to a hole in a tank)
Next, a hole has to be drilled in the bottom of the Grow Tub, large enough for the Bulkhead Fitting, but not too big. Assemble the Bulkhead Fitting in the hole as shown.
Step 4: Make the Bell
How it works:
The pump is constantly filling the Grow Tub with water, but adding water slower than the drain can suck it out.
When the tub fills with water, it gets to the top of the standpipe, and starts to flow back into the Aquarium. When this happens, it sucks all of the air out of the space between the standpipe and the bell. The Bell over the standpipe maintains the siphon until the Grow Tub is empty of water.
To Make the Bell:
With the wood saw, make 8 cuts equally spaced on one end of the 2" pipe. The saw can make cuts on opposite sides of the pipe at the same time, so make one cut, then one 90deg from that, then cut each 'tooth' in half. (Too detailed?)
with the plier, grab a hold of a 'tooth' as close to the base as possible, and bend it back and forth until it snaps off. Do this to every other 'tooth' and you will be left with something that looks like the top of a castle turret. Use the file to smooth things out and make them pretty, if you'd like.
The purpose of these gaps is to let water flow into the Bell easily when the siphon starts. This will make sure that the Grow Bed drains quickly.
Step 5: Set Up the Grow Bed
I used a 1" drill bit to cut a hole in my shelf for the drain. This let me put the Grow Bed in the center of the shelf, where the weight of it would be distributed more evenly amoungst the wall brackets. Don't want it falling off the wall!
To mark the location of the hole, put the Grow Bed on the shelf where you'd like it, and put the sharpie marker inside the stand pipe, tip down. Wiggle it a bit and it will mark where you should drill your hole.
Make sure that the bottom of the Bulkhead Fitting fits through the hole, and that the Grow Bed fits in place nicely.
Step 6: Prepare the Hydroton
After doing some research on the matter, I decided to use Hydroton grow media. It is clay balls, about 1/4" in diameter. They are pH neutral and inert, which is nice, because they won't leach stuff into the water and make me adjust the pH all the time like some gravels will. It is more expensive than gravel though. In the bag, it looks just a bit like dog food. I find it a bit odd...
Hydroton has to be washed before you use it. Nothing dangerous, it is just to get rid of the dust that inevitably is generated when thousands of clay balls get jostled around during shipment. Use a pot and a strainer, clean them in the sink (or tub). I used a solution of a splash of vinegar per wash them, and rinsed them with clean water. If you don't do this, you'll get brownish gunk in your fish tank. Who needs that?
Another tip - put a strainer in your drain hole before you start. You will spill some rocks, you will have to reach down the drain to get them.
Oh, and rinse twice. There's a lot of dust. I used the 2nd rinse water from the last batch to rinse the next, but my stones still dumped a lot of dirt into the tank. Use fresh water each time.
Luckily, beta fish are quite difficult to kill in my experience, I've heard they don't mind murky water that much. Either way, I'm still doing a water change soon.
Step 7: Set Up the Tank
Locate the fish tank where you want it. It will be tough to move once you fill it with water - water is 8.34 pounds per gallon, and there will be several gallons of water used here!
My pump has suction cups on the bottom of it to keep it in place. I stuck it where the intake was as close as possible to the bottom of the tank, with the discharge facing up (it rotates!) I connected my ball valve to the end of the Polyflo that is attached to the pump. This valve is all the way open. With the Grow Bed on its shelf, two 90deg fittings make sure that I don't have to bend the Polyflo to get it into the Grow Bed. You can bend it with a hairdrier, and it'll take a bend ok, but it is irritating, and I am lazy.
Step 8: Test the Bell Siphon
To make sure everything works properly before adding rocks, set up the system for a quick test. Attach the long 1/2" PVC pipe to the discharge of the Bulkhead Fitting. This long discharge will help to keep the siphon going. Put the Bell over the standpipe.
Running pumps dry is bad. They use the water they pump to keep themselves cool. Put enough water in the bottom of the tank to cover the pump. Turn on the pump and make sure it pumps water into the Grow Bed. If not, you may need a bigger pump. Now that you know the pump works, Add more water to the tank and turn on the pump. Fill the grow bed, and look for leaks on the Bulkhead Fitting. Also check to make sure that the shelf isn't going to break. That would be bad. Once the water level gets above the standpipe, water will start flowing through this siphon. It will be slow at first, and then SLURP! speed up as the air is sucked out of the Bell. Make sure that when the Grow Bed is empty, the siphon action stops. If the pump is going too fast, it may be adding water just as fast as it is draining. If this happens, close the ball valve a bit. Mark the maximum level of the water.
Step 9: Disaster!
The Grow Bed leaks! A little investigating, and I discover that the flange at the base of the standpipe has a little flat on it. I"m guessing that this is compressing the gasket non-uniformly, and when the Bell is placed over the standpipe, it squishes the gasket just a little more - making it leak.
My solution - O rings. I bought a pack of #18 O Rings at Lowes, for $2. Placed one between the standpipe flange and the gasket, and one between the bottom of the Grow Bed and the locknut.
Why #18? Because they fit nice and snug over the threads of the standpipe.
Re-assemble, test, success!
One note of caution - if you find this necessary, don't over-tighten the locknut - it can 'extrude' the O-ring: The spinning action distorts the Oring, making part of it squish out. This can damage the O-ring and make a bad seal.
Step 10: Add the Hydroton to the Grow Bed
Put a screen around the bell, an inch or so off. Little rocks clogging the intake will cause a flood. Or they get sucked down into the fish tank. Fill the Grow Bed with Hydroton, 1/2" above the maximum water level.
Do another fill test while watching. Rocks are heavier than water, though Hydroton is pretty close to neutrally buoyant. The grow bed may be heavier this time. Try to notice if it falls off the wall or not. Also, make sure that the siphon starts up and stops like it is supposed to.
If the Siphon starts slurping at the end, but does not stop, use the ball valve to slow the water addition into the Grow Bed until the Siphon breaks. Monitor the system for a few hours to make sure this doesn't happen to your system.
My initial testing was done without a screen around the Bell - as a result, smaller Hydroton bits were sucked through the siphon and dropped into the fish tank. Eventually, or course, a larger one made the journey, and clogged the standpipe, resulting in a failure to begin or end the siphon.
Use a screen. Mine was pretty easy to make - I used a tall 'fill it yourself' Deli container for olives (about 6" tall, 5" across at the rim, 4" across at the bottom). I drilled a lot of 1/8" holes as close to the rim as possible, to allow water to flow in from the bottom. I cut a hole out of the bottom of the cup large enough to remove the bell, in case the drain pipe gets clogged. It would be MUCH easier to get this in place before you fill the Grow Bed with Hydroton. There can't be any Hydroton inside the screen, or it will eventually get sucked into the Bell and clog the standpipe.
Step 11: Nitrogen Cycling
Biology lesson! This is sort of important, unless you hate your fish.
Fish excrete ammonium through their gills as they breath (this is all according to my research so far - feel free to leave messages to correct me). If this builds up too much in the water, it will poison the fish. Luckily for us, there are some helpful bacteria available that like to eat ammonium. They will grow on the surface of the Hydroton. They turn the Ammonium into Nitrites. That's not very helpful by itself, since Nitrites are also not good for fish. Another bacteria will eat these Nitrites and turn them into Nitrates. Plants like Nitrates, fish don't mind Nitrates. Plants feed on Nitrates and other stuff and give us yummy food.
All of this does take some time to occur though, so if you just throw fish into this system now, they will probably get poisoned before the Ammonium-Nitrites-Nitrates cycle can establish itself. To establish this cycle, you can add 5 drops of Ammonia to your water, and turn on the system. The Ammonia will spread through the system, soak into the Hydroton, and encourage these helpful bacterial colonies to establish themselves. This does take some time though, a week or two. An aquarium store should have supplies that allow you to check these Nitrate/Nitrite levels. Be patient. Unless you hate your fish.
If you want to learn more about this stuff, check out this link:
Step 12: Add Living Stuff
You can add fish and plants now.
Commercial Aquaponics systems are sized for a ridiculous amount of fish (Almost 1lb of fish per gallon of water). To do this, they have to optimize their Grow Bed size to ensure that the water is being properly filtered. They usually also use air stones to add oxygen to the water. This extreme system is not necessary, you can get away with a lot less. I'm using a betafish for my system to begin with, I'll add some goldfish in a few weeks. The amount of oxygen added by the Auto Siphon cycling constantly should be enough to oxygenate the water. Add fish to the system slowly, so that you don't upset the Nitrogen Cycle in the tank.
For plants, you can start them in Rockwool, and then transplant them into the Hydroton, or you can try to start the seeds directly in the Hydroton. The rockwool may promote root rot later on, so I'm going to try direct sowing, but I hear it is more difficult.
Step 13: Things to Add Next
1. An Overflow
In case of a clog in the drain, I really ought to add an overflow to the Grow Bed. It would require another Bulkhead fitting, installed above the Hydroton, on the sidewall of the Grow Bed. Polyflo tubing would direct any water back to the tank. The plants will get flooded for a while, but the pump won't run dry, I don't get 5 gallons of water on my floor, and the fish get to stay wet.
2. A lid for the tank.
I think my cat is going to either:
a. Accidentally go swimming
b. Eat Se�or Fish-Fish (his actual name, by the way)