Aquaponics build

[crsublette]

Not really that expensive depending on how ya go about obtaining the source water.

Rain water harvesting isn't that expensive if you know folk where to get cheap or free containers.

I imagine there's other options as well.

 

[MitchM]

I have RO/DI and well water available to me year round, so I'll leave the rain and snow melt for the outside pond.
I'll switch between the two depending on what water tests tell me.

 

[MitchM]

The bell siphons arrived today, so I installed them and plumbed the bottom sumps together with some unions.

 

[HTH]

I had to consult the net to figure out what a bell siphon was. If I understand right they let you run a pump full time and still get the cyclic flooding of the grow media. Neat system. Keep the pictures coming.

I have this setup which will eventually hold fish. Current plans are to convert the old greenhouse into a place to raise fry to where they can go into the containers. It would be fun to put some NFT tubes at about 5 feet. Grow some strawberries in the rafters Problem is keeping it cool enough.

 

[Catfishnut]

What I haven't figured out yet is how I'm going to control the water level from evaporation.

I was thinking of using an extra electronic sensor I have, but I can rig up a mechanical one.
I wouldn't trust the electronic one with the turbulence.

Mitch,

If you expect MUCH turbulence in the tank where the water level is sensed, then even a mechanical sensor or float switch is going to be problematic for you. If you have lots of turbulence it will read false low and high levels continuously and cause your pump or valve to cycle on and off constantly and that is not good for any mechanical device.

You need to incorporate a "debounce" logic circuit. In case you are not familiar with electronics, I will explain what a "debounce circuit" is and does. It is relatively simple in its theory, although construction and design can become involved for the layperson.

If you want the fill pump or fill valve to turn ON when the water level is low, but not everytime you get a false low reading from turbulence, you put a timer in the circuit. If whatever device you are using to sense the water level registers a LOW indication for at least XX seconds, then we will turn the fill pump/valve ON... AND we will keep it ON for a period of XX seconds.

You also add a HIGH-LEVEL sensor to turn the drain pump/valve ON if the level gets too high and apply the same logic.

The time settings of both circuits can be adjusted so that you can fine tune your level, even with the prescence of the turbulence.

There are timer relays available which do exactly this for you. You might want to investigate this avenue as it might save wear and tear on your pumps/valves.

Catfishnut

 

[MitchM]

Looks good Howard. I find that a misting system with an exhaust fan is pretty powerful for cooling. It helps if you're in a relatively dry climate. We're frequently around 45% relative humidity.

Catfish nut,
I get it. That makes sense. If I go the electronic route, I'll be using my aquarium controller which I'm pretty sure has some delay and run time limits which I can hook up to a water valve solenoid. Thanks for the idea. I can probably even hook up 2 solenoids, 1 to my RO/DI unit, 1 to my harder water well water and control which one switches on depending on the PH of the aquarium water.

If I want to reduce turbulence, I can also direct the outputs from the media beds and the aquarium to the two outside sumps only and have the level sensor located in the middle sump. Then there would be no turbulence, only slowly constant rising and lowering water levels.

The mechanical float would probably just be a humidifier float valve the and electronic version would be an electronic eye type.

 

[HTH]

I am curious why you need both timers and bell siphons?

I need to thank you for posting about aquaponics. It seems this place is working on becoming a desert with brutal hot dry summers. Regular gardening has become difficult and expensive with the water needed. NFT looks attractive. Need to do much more reading.

We will be using misters other places this summer but for this green house I am plan on going with swamp cooler pads in one wall and fans on the other. Maybe use a slow leak on the cooler feed to bleed water to the aquaponics to prevent mineral buildup in the pads, providing the plants can make use of them.

If this works out it should be interesting.

 

[MitchM]

Howard, the timers would be for the top up water to compensate for evaporation water loss. If you can imagine the water float switch bouncing up and down from the action from the bell siphons, then a timer on the valve supplying the water would prevent the valve from constantly switching on and off. It would only switch on when the water was consistently below the low water mark.
The pump and the bell siphons will be running 24/7.

I'm glad you're finding this thread useful.I wasn't sure if I should post it here, but since it's to be kind of an extension of my outdoor pond, I thought it would be ok.

 

[Catfishnut]

Mitch,

I have another alternative idea for the water level detection for you, if you'd rather not utilize so much electronics (all that extra wiring and buying timers, relays, etc).
You could construct a "baffle" zone or a "baffle" pipe in your top up water tank to level out or retard the fluctuations of the water level in the top up tank.

Mount a 6" PVC pipe vertically in the top up water tank with the bottom of the pipe sealed and the pipe rigidly attached to prevent it from floating up due to bouyancy.
Drill many small diameter holes in the wall of the PVC pipe (let's say 1/8" or ~3mm diameter) throughout the total length of the pipe (or cut fine slits).

The water level in the main top up tank may rise and fall quickly with the action of the bell siphons, but the water level in the perforated PVC pipe will take much longer to react.
There's your passive buffer timer (or debounce logic) that senses the overall water level more accurately.
Then you could install your float switch inside the pipe to monitor the water level without the float giving false low or false high level readings.

You would have to experiment with how many holes and what diameter they need to be to fine tune it, but I think this is probably a better scheme all around.
Obviously you would have to utilize a float and switch mechanism that would fit in the pipe or whatever baffle chamber you create.
I am thinking along the lines of a floating 'bob" like a plumb bob attached to a light plastic rod that operates the switch above.

Much less overall expense and engineering. Less items to possibly fail.

Catfishnut

 

[MitchM]

I have a digital powerbar that's controlled by my aquarium computer, so it would only be a matter of plugging in the two 120v solenoid switches to that. I'm already using that setup in my other aquariums.
The perforated pipe is a good idea for a buffer.

 

[HTH]

Catfishnut the same principle as a chicken water?

It is more then OK with me Mitch. People can always opt to not read topics they have no interest in.

There is something I want to try this summer on the water level. Microchip has added a capacitive timing unit to some of its new micro controllers. The plan is to add metal tape strips up one side of the container. The capacitance between two strips is directly related to the height of the water and with this new on chip peripheral it can be measured. Because the metal tape is on the outside of the container there is no fouling or corrosion problems. Microchip talks about doing this in an app note so it is not my invention. The parts to do this are not expensive.

If it works out I will post about it as it could be used to monitor water levels in filtration chambers etc.

 

[MitchM]

So the metal strips are detecting the difference between the temperature of the ambient air and the water temperature?
Water is slower to heat and slower to cool, but you will still have two times per day that the temperatures will be equal, no?

 

[HTH]

So the metal strips are detecting the difference between the temperature of the ambient air and the water temperature?
Water is slower to heat and slower to cool, but you will still have two times per day that the temperatures will be equal, no?

It is not temperature related. Capacitance is the ability of a body (in this case the metal strips) to store an electrical charge. The water level on the other side of the plastic wall effects how much charge can be stored. This gadget times how long it takes to charge the strip to some small voltage. If the strip will only hold a little charge it will come up to voltage fast. As the ability to hold charge increases the time it take to charge the strip to that same voltage increases.

The voltages and currents are all quite small in case you are thinking about safety.

 

[Catfishnut]

Catfishnut the same principle as a chicken water?

No, not like that. The chicken waterer works on the principle of a vacuum to retain the water level in the drinking pan while holding a reservoir of water above that doesn't drain out.
That's almost akin to the bell siphons operation, sort of.

What I was thinking of was an individual chamber which, because the water exchange ports were so small, the water could not fill it nor drain from it very fast.
As the water level in the main tank rose and fell 6-8 inches in a matter of 30 seconds, the water in the perforated tube would rise and fall only 3-4 inches in a couple minutes.

It is just a matter of buffering the rise and fall of the water level for sensing purposes.

Catfishnut

 

[Catfishnut]

It is not temperature related. Capacitance is the ability of a body (in this case the metal strips) to store an electrical charge. The water level on the other side of the plastic wall effects how much charge can be stored. This gadget times how long it takes to charge the strip to some small voltage. If the strip will only hold a little charge it will come up to voltage fast. As the ability to hold charge increases the time it take to charge the strip to that same voltage increases.

The voltages and currents are all quite small in case you are thinking about safety.

The water acts as the dielectric in between the plates of the capacitor. Changing the level of the dialectric medium (the water) changes the capacitance value. The higher or lower the water level is, the different value the capacitor has and the electronic circuitry reacts according to the changing capacitance value.

Catfishnut