An unplanned aquaponics build

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An unplanned aquaponics build
1/1/0001 12:00:00 AM

I got a call from a buddy of mine.  He had decided to minimize his world in exchange for travelling with his new wife in addition to supporting her continued education needs (this is a great guy!).  He had called me because he had several tilapia that he needed to find a new home for. 

We had spent many moments over the past couple of years discussing sustainable farming techniques – quite a bit of time around aquaponics.  This was the guy that had actually introduced aquaponics too me.  When needing a new home for his fish – I was the first guy he thought about to take them.

The problem with this is that I didn’t have an active aquaponics set up at the time.  I had purchased all the parts for a small set up.  But I am a researcher and a planner.  I tend to put stuff off until I am absolutely sure that it is what I am going to want.  The small system I wanted quickly ended up not being enough for my plans.  All the parts I bought for my first system eventually got parted out to other needs on the farm.

No aquaponics system and no fish tank!?  What am I too do?

“Sure, bring the fish over!  I will figure something out.”

Time to figure out what to do with these fish.

Gathering the tanks

The first thing was to figure out what parts from the original aquaponics system I still had and what shape were they in.  What was I going to need to purchase to pull this off?  We started by collecting all the water troughs we were using on the farm (originally planned for grow beds and fish tanks).

The first tank to recover was one of the tanks in the red wattle hog yard.

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She didn’t fit the 50 gallon tank anymore any how!

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Then we had to take one from the pot belly / water foul yard.

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We couldn’t make up our mind about which bigger tank to use for the fish tank.  We had a 100 gallon tank and a 300 gallon tank.  The kids were using the 300 gallon tank to swim in (as we had not yet opened the pool).

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The horses like this as their water bowl too so we didn’t take it from them.

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We ended up using the 100 gallon tank which was currently being used for the horses on another part of the property.  They won’t miss it though!

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Prepping the grow beds and fish tank

Now that we had all the tanks that we would need we had to get them washed up and prepped for use.

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We were planning on using a total of four 50 gallon tanks for the grow beds.  And the 100 gallon tank for the fish. 

Aquaponic tank math

If you know aquaponics you know that this math is an equation for disaster in a couple of ways. The math doesn't support the drainage capacity in the sump tank. It also doesn't support fish happiness when your sump tank is your fish tank and you pump all of the water from the fish tank to the grow beds.

Here is what we are aiming to build:

Generally you have a sump tank (where the water from your grow beds drain into) that is at least the total capacity of your draining tanks. 50 gallons * 4 grow bed containers = 200 gallons total capacity needed? Since our sump tank is only 100 gallons that doesn't quite work given that all of our grow beds may drain at the same time into the sump tank. But when you fill the growbed with media (usually a rock of some kind – lava rock in our case) you are left with about half or less capacity in the grow bed for water. The equation then is really 20-25 gallons * 4 grow bed containers = 80-100 gallons which means we need a sump tank of at least 100 gallons.  We are roughly ok on this point.

We still have a problem though.  If our grow beds need 100 gallons to be full and start the drain cycle and our sump only holds 100 gallons – and our sump is also doubling as our fish tank – our fish may find themselves flopping about at the bottom of the tank.

Knowing that we might have this issue we chose to go with the 100 gallon sump/fish tank for the time being.  The grow beds filling and draining at the same time doesn’t happen often.  We can address this issue later.

Once we got our math issues figured out we needed to start collecting the construction bits for building a base for the tanks.  I had a stack of 8x8x16” cinder blocks from my originally planned system so we stuck with that plan.  I chose to stack the bricks end to end, two brick high.  This was just enough height to put the bottom of the grow bed just higher than the top of the fish tank.  This means that we can easily use gravity to drain our grow beds into our fish tank as needed.  We also used green 2x4’s to span the bricks.  This allowed us to use less brick stacks as the weight was dispersed over the boards to the bricks.  It is important that you make sure that everything is as level as you can get it.  Use wooden shims if you need them!

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Next we needed to drill a hole in the bottom of each grow bed big enough to accommodate our bulk head fittings.

Aquaponics lingo alert!

You might be asking what the heck a bulk head fitting is!  It is a plumbing fitting that allows you to make a water tight seal through a container.  Generally these have wide flanges and long threaded bodies.  The threaded end is passed through the container with a rubber washer on either side of the container.  The nut then threads on the threaded section and presses the two rubber washers tightly together to make a water tight hole in your container.  The next important part is that the fitting body is threaded on the inside and the outside allowing a threaded pvc connection to attach to your container.

If you don’t want to pay the money for a plumbing bulk head fitting you might try an electrical connection with an o-ring.  They are quite a bit cheaper thought not quite as stable a connection.

The size of your bulk head fitting and plumbing size will drive the size of your hole.  For my grow beds I chose to use 3/4” pipes for the drain pipe and stand pipe (we will cover the parts of the auto siphon shortly).  The outer diameter of a 3/4” bulk head fitting is roughly 1-1/2”.  You will want to drill this hole at one end of your grow bed to ensure even water distribution.  Don’t drill your drain hole in the middle of the container.

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Then I threaded all the bulk head fittings into place.

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And then we tested the water tight seal.  Worked as advertised!

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Here come the fish

Then the fish arrived!  Woo hoo.  My buddy brought me six 8” tilapia.  We still weren’t ready but it didn’t take too long to get ready for them.

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We immediately got them into the fish tank to start equalizing the water temperature between the water they came in and the water in the fish tank.  You will notice in this picture that we also dropped a bubbler into the buckets with them to ensure that they got a good supply of oxygen.

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Once we were to this point we had two tasks to get done.  First we needed to start collecting the grow bed media and wash it.  Second we needed to start plumbing the system.

Washing the rocks

I planned on using the rock I had in my various planters around the property.  We have a bunch of lava rock which I hate!  It gets everywhere.  But the rock that is in a planter is in no condition to be used in a grow bed.  It is filled with dirt and grass and leaves and twigs.  Yuck.  Time to get washing.

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If you are going to buy rock for your system try to find 3/4” gravel.  You will notice that some of the rock in this picture is just too big.  Big rocks take up too much space and can block water flow as well as get in the way when trying to plant a seedling.  Conversely small rock is also not appropriate.  It too can block water flow.  And while it won’t get in the way of planting it is not big enough to lend support to your plants in heavy winds or in order to maintain a heavily fruited plant in an upright manner.  Small rocks can also clog your plumbing.  I am using what I had on hand…beggars can’t be choosers.

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Locating and washing rocks took a long drawn out 3 days.  We didn’t like it at all…but it had to be done.  There was quite a few swimming breaks spread out through this task. 

(the pool was just opened…still dirty from the winter)

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What a good helper boy!

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Plumbing time

While we toiled over the rocks I also tinkered on the plumbing.  There are two primary systems to be plumbed in a simple aquaponics system such as the one I had planned.

  1. The pump from the sump to the grow beds
  2. The drain from the grow beds back to the sump

From the sump to the grow bed

The plumbing from the pump to the grow beds is quite easy.  In this systems case I am pumping up about 4 feet from a sump that is in between the grow beds.  The pump output is 1-1/4”.  I reduced this immediately to 1” pipe as I had 1” pipe fittings and no 1-1/4” fittings.  At the top of the pipe I went to a 1” tee.  At the 1” tee I reduced the left and right output down to 3/4” pipe.  From there I branched out to the grow beds. 

There is one exception in that on one side of the tee I added an additional tee to allow me to have a back flow pipe to relieve pressure on the pump.  This way if I turned down the output into the grow beds the remaining pressure would go through the wide open back flow directly into the sump.  This should be done for two reasons.  The first is the obvious reduction of strain on your pump.  But the water jetting back into the sump/fish tank creates a lot of bubbles and commotion in the water.  This helps to off gas any carbon dioxide in the water and re-oxygenate it for the fish.

The pipe with the roaring flow is the return back flow pipe!  Look at those pretty bubbles!

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Plumbing tip of the dayBe sure to include a simple ball valve on all outlets from your pump. This allows you to easily adjust the pressure in your system and control where and how fast your water flows.

From the tee at the top of the pump it is simply a matter of running the pipe to a tee where you plan to have the water flood into the grow bed.  I like to let the water into the grow bed on the opposite end of where the water will drain.  In this system the water is set to drain as close to the sump as possible.  This means the input for the flood pipe needs to be as far away from the sump as possible.  Where I add a flood connection I start by adding a tee connecter to the main pump line.  The tee then has a short piece of pipe inserted into it to allow me to attach a ball valve to control the flood rate into the grow bed.

I like to angle the ball vale down just a bit so that I can control the splashing that might otherwise occur.  This system required two flood outlets per side.  The end flood connection uses a 90 degree elbow instead of a tee.

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Once everything is dry fit and appears to look correct – don’t glue anything.  We need to work on the drainage.  Then we can try to run the pump prior to gluing up.

More plumbing advice
  • Have a plan on paper before you start plumbing anything.  Especially if you plan to use PVC (which requires glue).  You can use PEX if you would prefer.
  • Measure twice and cut once.  Pipe is pretty cheap but why waste money?
  • Dry fit everything!
  • Once everything fits, don’t forget to glue at least the pressurized system.  After turning the pump on you may find that everything stays together.  But it won’t stay together or ever.  In the system that we have currently planned there is no safety for your fish if your plumbing fails.  The pump is always pumping…if the water doesn’t return to the fish tank your fish will die! (we will rectify this shortly)

From the grow bed back to the sump

Both of the two plumbing scenarios have their own complexities.  However, plumbing up the pump line is fairly straight forward whether you have done plumbing or not.  Plumbing the drain lines is a bit more scientific in that we need to use a method called an “auto siphon”.  There are a few ways to do this but we are going to use a mixture of improvements from various aquaponics all-stars to create our auto siphon.

Here is a quick animated pic of a standard auto siphon.  The pipe that extends the height of the bulk head fitting is called the stand pipe.  The larger pipe that goes over the stand pipe is called the bell tower.  You will see that the water enters the tank.  Once the water reaches the top of the stand pipe it starts to drain out in a trickle fashion.  The trickle quickly becomes a flow once the water level is great enough to cover over the hole in the stand pipe.  Because the bell tower is over the top of the stand pipe it creates a suction effect that drains the tank.  The trick is in getting the water in-flow to be fast enough to fill the tank and start the suction.  But slow enough that the out-flow can drain faster than the fill.  This can be tricky with the simple diagram you see here.  Another interesting part of this image is the drain pipe under the tank exiting the bulk head fitting.  It is important that the pipe is not too short (such as when you put the grow bed directly over the fish tank).  Having some length to that pipe ensures that the suction effect is strong enough to drain the tank.

However with some advances in auto siphons these days there are ways to ensure that this is easier to tune. 

  • Add a venturi to the top of the stand pipe: We can add a simple improvement to the top of the stand pipe called a venturi. Adding a wider top to the stand pipe ensures that the in-flow of water is far greater than the capacity of the drain pipe itself.  The effect that is created is called the “Bernoulli’s Principle” which pushes the water at a faster rate causing the system to force drain itself.  This helps you manage starting the drain cycle as well.  Thank you Affnan for your improved design!
  • Breather tube: Sometimes you will have an issue breaking the drain cycle.  The in-flow trickle will be fast enough to provide a continuous suction and drain flow.  The suction with the continuous in-flow means that the bed never fills (which will kill your plants).  The suction of the drain cycle has to be broken.  This can be achieved by ensuring that the in-flow is slow enough that the suction doesn’t get enough water to sustain itself.  Or you can add a breather tube which feeds the suction an air supply at a specific point.  In the picture below you will see that when the water gets to the bottom of the “air break tube” enough air is allowed into the suction chamber to break the suction.

There is another part that somewhat adds to the success of this style of siphon.  You need a sleeve to keep the media off of your bell tower.  This allows you to periodically remove the bell tower from your system to check on the flow of your system.  This will also allow you an easy way to clear the roots away from your system (or other blockages).

Measurements

The stand pipe is a 3/4” pipe.  The height of the finished product should be 1” lower than the top of your grow bed.  Measure appropriately.  You need a threaded end to screw into the bulk head adapter.  Then the stand pipe glues into the threaded end.  Next comes a 1” or 1-1/2” reducer down to 3/4” to create the venturi at the top of the stand pipe.  Ensure that the reducer you buy has an hour glass type shape (some reducers are terrible square which doesn’t work as well).  Don’t glue the stand pipe into the bulk head adapter!  Finger tight is good enough.

The bell tower is created with a 2” pipe.  The top of the pipe is fitted with a 2” end cap.  The very bottom of the pipe has half circles drilled into it.  Just enough to allow water under the pipe.  If you choose to put the breather valve on it you can either drill a hole directly in the cap or you can use an NPT fitting and attach a 1/4” hose to it.  The bottom of the tube should be just higher than the input of the bell tower.  Once the water drops below the tube air will rush to the top of the bell tower and break the suction.

I used a 3” tube for my outer guard.  However, I would suggest that you use a 4” tube so that you can get your hand down into it!  This guard should have as many holes drilled into it as you have patience for and at all levels of the tube.

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Once all of the plumbing was loosely put in place it was time for a wet dry-run.  With people standing by to turn the pump on and watch for leaks we turned the system on.  We were watching the tanks to see them flood.  Then we watched the auto siphon’s kick in.  Since we hadn’t adjusted the in-flow and out-flow yet we turned the pump off once all the auto siphons kicked on.  We filled and drained the grow beds several times just to watch out any crud we might have missed.

Then we glued up the system and waited for 24 hours for the plumbing to dry.

Tuning the system

Once the plumbing was dry and ready for use we turned the system on.  CRAP!  There was a small leak in one of the connections.  No worries though!  I cut it out and re-plumbed it.  Wait another 24 hours. Then we turned the system on again.  Once the plumbing seemed to work as intended we started to adjust the in-flow using the ball valves.  The key was to get the in-flow fast enough to not take all day to fill the tank but slow enough to ensure that the suction was able to break (as I didn’t install a breather valve on my bell towers…but I will).  Working with four grow beds, don’t forget that you can do final tuning on one bed at a time.  You need to slowly turn up or down your grow beds.  Micro adjustments across the entire system is best.  Once you see that your beds fill and drain themselves without any additional tweaking you are ready for the next step (which is not my next step).

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Adding the fish (don’t follow me beyond this point)

With the water flowing through the system as planned I was ready to add fish.  Don’t do this in your system though!

For a new system from the ground up you need to let your system run for a while.  You will need to spend time getting your water ready for fish.  You can do this by adding gold fish or some other cheap but hardy fish.  They will need to do their business in the water to get the ecosystem ready for the real deal.  You need a couple of bacteria to show up in your system to convert the amonia (fish pee) into nitrites and then nitrates.  Without this interaction the fish will muck up your water and eventually kill themselves.  Also, your plants won’t get the nutrients that they need to survive either.  Here is a quicky on the aquaponics cycle.

In my case though I am receiving two 5 gallon buckets with six 8” tilapia.  The 10 gallons that are entering into my system have all the bacteria I need to get a jump start on my system.  I used a test kit to check the ph of the water (as well as a few other things such as chlorine levels).  The water was good.  Once the water temperature was consistent between the buckets and the fish tank we poured the fish into their new home. 

Be caution on this approach with your system.  You really need to appropriately cycle your system.  You can do this with cheap fish…or in a fishless manner.

Make sure that you put a lid on your fish tank once you put your fish in though.  I didn’t immediately do this and one of my more bold fish immediately threw himself out of the tank.  The cats loved this!  It was like the gods had delivered a huge fish straight from the clouds. I was able to save him though and then put a lid on the tank.

Bring on the plants

You can actually add the plants before you add the fish.  I didn’t, but you could.  The plants aren’t likely to immediately kill themselves.  Be aware though that you need to a cycled system to support the plants as well as the fish.  For your first round of planting you might consider using something on the cheap side.  We were ready to plant at the end of the season which meant that we had access to several half off veggies.

The kids and I went to all the nurseries we knew of.  At each place we were able to find lots of cheap plants.

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We brought them home and immediately started planting.

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We were able to add quite a variety to our grow beds.  We have beans, all sorts of peppers, cucumber, squash, egg plant, tomatoes, a bunch of herbs, basil, and bell pepper.

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Two weeks after planting

We have now had the system running for a week or two.  We have since added a couple new plants.  But we have not yet lost any plants as expected.  Pretty much all of our plants are growing “like weeds”.  It is quite amazing.  And the only weed that we have had to pick out of our system is one that came with a seedling.  Otherwise we have seen the addition of quite a bit of (veggie) fruit.  We have peppers, bell peppers, tomatoes, and egg plants growing pretty good.

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What would I do differently the next time?

  • Use a larger drain line than your input line.  In our case we used 3/4” input pipes and 3/4” drain pipes.  I think 1” to 1-1/2” drain pipes would have been better.  This means we can fill the grow bed slightly faster as the drain would be considerably faster.  Starting and stopping the drain would have been easier too.
  • I will never again use rock that was used for another purpose.  Washing the rock appropriately took D A Y S!  And it was boring time consuming laborious work.  I didn’t like it.  The kids didn’t like.  Thank god I have so many kids to help with tasks like this.
  • I will never again use lava rock.  I had long finger nails that really needed to be trimmed when we started planting.  By the time I was done planting my nails were worn down to the nub and the skin on my finger tips were entirely removed.  Also, digging in this type of rock is incredibly difficult as the rock is very grippy against itself.  This media type is not efficient enough for big systems.  And it is not enjoyable enough to make working in this system something you look forward too.  This rock type just sucks!
  • Use a 4” guard tube so that you can get your hand into the siphon area for easier clean up.  In a 3” tube I have to use my kids hands.

Issues I have had so far with this installation

  • Not having a lid immediately after we added the fish resulted in a fish jumping out.  Make sure your lid is ready and waiting.
  • Our summer was starting when we added this system to the farm.  Given that it is only about 100 gallons the water temperature fluctuates pretty easily and quickly with the heat of the day.  It was never my intention to keep this small system running.  With a larger body of water the temp won’t fluctuate as much.  But for a small patio system like this heat and cold can be an issue.  For us we intend to add the 300 gallon tank into the mix as the fish tank.  We will keep the 100 gallon tank as a sump.  The grow beds will drain into the fish tank and the fish tank will overflow into the sump tank. The pump will continue to get its water from the sump.  This means that fish tank will always keep a consistent height.  We also plan to put the 300 gallon tank in the house for the time being to help battle the temperature.  If you can’t do this you might consider running some plumbing under ground to use geo thermal concepts for cooling.  The deeper you go the better.  Shoot for 5’.
  • One day I got a panicked phone call at work stating that the pump had died and the fish had no water.  Someone apparently jiggered the system so that water was draining from the system.  Given the sump/fish tank arrangement the pump just kept pumping and emptied the system dry.  It was caught almost immediately and filled back up.  The pump didn’t like running dry but someone didn’t kill itself.  This issue will be resolved by ensuring the plumbing doesn’t move under the stress of kids and pets.  But it will also be hardened by adding the 2nd tank mentioned above to separate the fish tank and sump tank.
  • We have already ran out of planting area.  The originally planned system had 8 grow beds.  I may expand this system to the originally intended 8 grow beds until our green houses are up and functional.
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