Easy Aquaponics From "mostly" Re-purposed Materials




About: I like fishing, boating, and gardening as well as learning interesting ways to do things. This site is perfect for me because I like to "fiddle".

Okay folks - let me have it. My first Instructable was some time ago and it wasn't much so I thought to myself, "how can I really bring some value to the community" and this is what I came up with. My son (15) and I built this over two weekends. Granted, if you had the supplies ready and handy, you could easily do it in a day if you really hunkered down.

Without further delay, I present to you our (roughly) 200 gallon aquaponics system, built from re-purposed wood, a cheap pond kit, some PVC, and lava rocks.

Step 1: Tearing Down the Old Raised Beds and Getting the Base Built

What really prompted this project was the fact I was getting very tired of the fire ants getting into my raised beds. After losing much of my crops to ants, I decided I was going to grow in water via hydroponics. Then, I was able to convince my wife to let me put a fish tank on the deck for another aquaponics build - so it was on ;)

Thanks to the help of my son, all of the 6" screws were taken out of these timbers, we cut them to size and ultimately built a smaller version for the tank and used some of the pieces for legs and supports on the grow bed. It is worth noting that we were able to reuse most of the screws that came out of the timbers as well so I did not have to buy any.

The size of my grow bed and the size of my tank were based on mathematical calculations made by me based on the amount of pond liner I had available to me. I bought the kit (see picture) on Craigslist for $25 - it was still brand new in the box. The liner was 8x10 so I had to figure on how much I could use of this. I elected to build a tank that was 2x7 x18" deep and grow bed was 1x7 x1' deep for optimal root space. Of course, if you are using a different size liner, just keep in mind that your depth will take off length and width from ALL sides (if you go 1' deep, you need to take off 2' from length and width, which works out to 1' all the way around)

Step 2: It's Coming Together Now

We built the tank entirely from landscapes timbers for extra rigidity as they are less prone to bowing in the middle. To strengthen them, we did add an additional screw in the middle of the long runs so that each timber is securely fastened to the one below it to remove the potential of bowing on the long side.

The grow bed was pretty straightforward. I measured the inside diameter and calculated that I would need 3 deck boards for the width (note that the deck boards were all leftover from when we built the deck a couple of years ago). I then used landscape timbers for the legs and supports that the bottom boards would sit on. I also used deck boards for the sides with the exception of the two ends. I ran out of enough deck boards but had a few scrap 2x12 pieces that I was able to cut a few inches off and use them (note: save all wood pieces over 1' if you have room to store them - you never know when they will come in handy).
Note that the measurements have to be pretty precise on all this because once you put a couple hundred pounds of rocks and almost 500 pounds of water in this bed, it will not be very happy if it uneven and out of level. That being said, there is a little room for forgiveness - just not much :)

Step 3: Getting It to Hold Water

The next step is laying down the liner. Remember that I cut the liner in a way to get both the bed and tank out of one liner. Now, we put them in to our built structures. The MOST IMPORTANT thing here is to put them in with a little slack. As the water is put into the system, the liner will fill all the small cracks, etc and without some play in the liner, you run the very real possibility of ripping it as the weight of the water pushes on it.

I used the felt paper nails you buy for roofing to hold the liner in place. Note that I only put them on the very top of the liner so there is no risk of leakage around them. There may be other things that would work better but these worked awesome and I just so happened to have half a box left over from when I built my shed so it is another thing that cost me no money.

You will notice that I have already added lava rock to my grow bed. This was primarily so I could keep the liner in place while I tested my Bell Siphon.

What is a Bell Siphon you ask? In the system, water is constantly being pumped into the grow bed. As the bed fills up, we use this siphon to quickly release the water back out of the bed. This allows for roots to get water and then removes the water off of them, creating a constant cycle of nutrients and water to the roots.

How to make the Bell Siphon. My apologies, I did not take pictures of this, but I feel that you can follow me pretty easily (and you can google images if you don't). Most Bell Siphons have a tube running from the top to the bottom - mine does not. If you have ever seen one or google image it, you will know what I mean. I did not use an air suction tube. Instead, this is how I make mine:
Step 1:
1' PVC is your drain tube (see pic) and needs to be mounted securely to your bed and go through it to your fish tank. Your 1" PVC should be 1" below the lowest point of your liner. (actually about a ½" but I give the extra half to be on the safe side
Step 2:
A 2" PVC pip with a cap should be cut to where it stands (with the cap) approximately 1" higher than the highest point of your 1" PVC. On the bottom of this, you will need to cut small slits so that water can enter into it but rocks, etc cannot. Your HIGHEST slit should be no more than 2½-3" as whatever your highest slit is in this pipe is what your constant water height will be in your bed (some water will always stay in the grow bed. The siphon will suck air when the water gets to the first air slit and it will break the siphon. Put the 2"pipe over the 1" trying to center it as best as you can.
Step 3:
Cut a 4"PVC pipe to 1-2" above the tallest point on the 2" pipe and drill holes all over the place. The only purpose of this pipe is to let water through but create an additional block against the rocks.

(I know, I spent more time on the siphon, but it is a VERY important part of the system)

Step 4: Putting Together the Rest of the Plumbing

Now, what you can't see in these photos is that there is a 1" PVC pipe running from my pump to the opposite side of the grow bed. It is hidden under the bed. I used a T-splitter to create two water streams. One goes to the bed and the other is going long-wyas doen the strawberry towers and will be set to a trickle.

The 4" pipe below is being used as a return pipe for the water from the strawberry towers. Where the towers meat the pipe, I have also created another growing spot so the entire pipe is filled with rock.

You will need PVC cement to attach/glue the connections. Make sure you get it on there good so there are no leaks.

Step 5: Done - FAQ

Upon completion, you will need to "cycle" your system before putting fish and/or plants in.
There are many ways to do this, but the most accepted way is to go ahead and put in plants and use seaweed extract (in accordance with label directions) to build up bacteria needed for the system.

Other ways to cycle system include urinating in it and waiting a week or you could throw everything together and just take out the few fish that will die in the process.

I put together a few things you may find interesting or that may come up as questions although I do welcome any questions and feedback.

1. How does the system work (biologically)?
Fish waste is pumped up through the system into the grow bed where bacteria convert it to nitrates for the plants. The plants then use those to grow, effectively cleaning the water or filtering the water for the fish. It is a completely closed loop system.
2. Do I need to monitor the fish/water?
As a typical rule, I would say "yes, of course". That being said, once your system has cycled and is stable, you should be able to let it be with the exception of feeding the fish.
3 How many fish do you need?
Most agree that about 1 10-12" fish per gallon of grow bed. You can calculate your rough grow bed volume with the formula - length * width * depth * 7.5 as there is roughly 7½ gallons per cubic foot of area.
4. Why did I grow goldfish instead of edibles like trout or tilapia?
Because I live on the MS Coast where I can get plenty of fresh fish much larger than what I can grow. Also, the temperature variances will allow me to grow goldfish through heat and cool lessening the chance of loss of fish in extreme heat or the occasional freeze in winter. Plus, my wife thinks they are pretty.
5. How did I make strawberry towers?
cut about halfway through the 4" PVC and use a heat gun to soften the plastic then pushed in on the middle with a hammer (softly) to form it. Use a filer/respirator though as PVC can release harmful chemicals when heated to extremes and you don't want to breathe it in.



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    31 Discussions


    6 years ago on Introduction

    It has been almost 4 weeks since we built the system and the system is leveling out and over the past week, the tomatoes have just taken off. The strawberries never grew so I think the roots we got may have been bad, c'est la vie. Anyways, thought I would post an update :)


    5 years ago on Introduction

    I have a question. How well do you think a set up like this would last in extreme heat? The Hydroponics shop i went to stated that a wood base set up is a bad idea (because i am in arizona) and the wood will degrade fast to where the system would collapse on itself.

    5 replies

    Reply 5 years ago on Introduction

    I live in South MS where temps are triple digit with 100% humidity over summer and I see no signs of degradation. I have also helped build at least 20 other systems made from wood over the past 2-3 years and am not aware of any that have been compromised due to heat.

    That being said, I would not build it out of something like OSB. I used solid wood, almost all of which was treated material. Be careful who you ask for instruction and do your own research (as you are seemingly doing :) ). I have noticed over the last few years especially that there are a lot more people who read a couple books and watch a few Youtube videos that thing they are experts and go open small stores selling net cups and think they know it all.

    If you want true building advice in your area, ask a contractor what their thoughts are. And I guess when it all is said and done - do what you want. If you build a system like this, the wood I used, if I had to buy it, probably would cost less than $50 (landscape timbers and a few deck boards) so if it tears up in a few years, just build another one. It will give you another project to do :)


    Reply 5 years ago on Introduction

    Well, Arizona doesn't have the %100 humidity it does have triple digits easily during summer though. I like the sound of the wood honestly and the price for building it myself would be better than the $1600 that the aquaponics shop wants for a system that will have a 30 gallon tank and one grow bed. I admire your tank and I know it will be MUCH cheaper to build it than buy it. I am just new to this whole thing. By the way if you haven't looked up on planting them, look up Alpine strawberries if you want some good strawberries. The wood prices I looked up for the materials for me showed up to be around $250-300 which to me is much worth it for a larger tank and grow bed.


    Reply 5 years ago on Introduction

    I assume that you are looking to build a little larger than mine here if you are looking at that much for wood. Also, check into using landscape timbers for the major supports instead of 4x4's as they are about half the price (I usually get landscape timbers when they go on sale for about $1.50-$2 vs $7-$8 for 4x4's.

    Something you may also want to consider is building them out of IBC containers - I have n example of one I just built as part of a greenhouse build that has two fish tanks and 3 grow beds - total build cost for just the aquaponics system was around $300 I would guess (main cost in IBC containers at $60 each)

    Check it out at https://www.instructables.com/id/Greenhouse-Addition-and-Aquaponics/ and be sure to vote for it ;-)


    Reply 5 years ago on Introduction

    I already checked out your greenhouse addition and it is awesome. By the way thank you for your instructables and happy easter.


    5 years ago on Introduction

    Very nice project and I am glad I ran across it. I am getting ready to build my system this winter and I have a question or two.
    1. how is the volcanic rock working (is it just cinder rock?). I ask because i have a huge area of volcanic rock that the previous owner installed (20 ft X 60ft) and I would love to put it to better use.
    2. did you screen it down to a specific size? if so what size?
    3. did you pre-rinse the rock before installing?
    4. does it affect water chemistry? or the fish ?
    Thank you for the instructable

    4 replies

    Reply 5 years ago on Introduction

    Thank you and glad to answer questions :)
    1. Not sure the difference of the rock - this is the stuff you buy at Home Depot for about $7-$8/bag that many people use in their beds so I assume it is the same stuff.
    2. Not really. We rinsed it off and did not worry about the exceptionally small bits but we did not specifically screen it.
    3. Yes. We did this mostly for water clarity though. I am not aware of any chemicals in these rocks. We did it so the water would not take as long to get the red out.
    4. I have noticed no ill-effects.

    One thing I can say is that if I were getting the rocks free or already had them, I would use them again. I would give second thought to using them if I were paying for them though. Initially I used the Lava rocks for cost and weight (they are much lighter than the same volume of neutral ph gravel/river pebbles). The downside I notice is that when you have to remove plants it can be a chore because the roots really grab on to the porous rocks.
    Good attributes allow for more bacteria though so I believe the water gets cleaned faster and allows for a little more plants in the same area, but I have no conclusive data to support that.

    All in all it has been an excellent system and I have pulled probably close to 10 gallons of Romano tomatoes off one plant, at least a dozen cantaloupe, close to a hundred cucumbers, numerous strawberries (uncountable as my daughter (6) usually gets to them before I know about it), and more. I found that peppers and zucchini do not do well in the system. Leafy greens should flourish but I have yet to attempt any.


    Reply 5 years ago on Introduction

    Nice system, I like your use of the verticle grow-pipes.
    Volcanic rock is good due to its porous attributes; lots of hidey holes for happy bacteria. The best for aquaponics is expanded clay which, like the volcanic rock is porous, but has the added attributes of being smaller (0.5 inch-ish) and lighter. It does have the down side of being more expensive though (avoid the ultra-cheap stuff; it crumbles very easily and takes forever to stop floating (weeks if you're unlucky).


    Reply 5 years ago on Introduction

    Thank you. for your comment/feedback.
    I chose the lava rock because I knew it would work, was lighter than gravel to fill the same area, and quite frankly, because it was easy to find locally (expanded clay is not available in my local area anywhere I could find).

    It has done very well in the system but can be cumbersome removing the plants because the roots get tangled in them because of their super-porous nature.


    Reply 5 years ago on Introduction

    Thank you, great information. It looks like I will be able to save some money on my build.


    Reply 5 years ago on Introduction

    I found most of the lumber and such in my shed, but did buy quite a bit too. It is very possible, however, to get almost all the parts free from scrap less a few custom pieces like the plumbing through the wood on the siphon and the actual liner/pump

    I hope you find all the pieces and do great :)


    5 years ago on Introduction

    I think this is a great concept...good for you...and thank you and your Son for Sharing it.

    1 reply

    6 years ago on Step 5

    That's a sweet little system. I'm working on putting one together in Western NY State - I'll need either a greenhouse or a shed though, our winters get really cold and an indoor system is the only viable option.

    1 reply

    Reply 6 years ago on Step 5

    That is awesome. I have been toying around with the the idea of greenhouse as well. I live on the MS Coast so we really only have two seasons - hot, and not so hot with the occasional freeze. I want to do a greenhouse-based system as well for tropical and subtropical plants.

    Don't let the greenhouse hold you back though. Do a small system in your garage, basement, kitchen in front of a window, etc. I see small fish-tank-sized systems for indoors that are great for getting into it.

    One note though on indoor systems - stay away from anything that needs pollinating. Most indoor systems stick to leafy greens (lettuce, spinach, etc) and herbs. Many of these you can actually float right on top of a fish tank :)

    Good luck! It is a fun hobby.