Aquaponics - New air lift design

If you pump air down into a submerged tube, when the bubbles rise to the surface, by virtue of the fact that they take up some space, they change the average density of the water in the tube.

The result is that the new, lower density water floats, and you get water sticking up above the surrounding water.

In short, you get a pump.

This is nothing new, and even if all you do is stick some bubbles at the bottom of an aquarium and let them rise to the surface, you are seeing what has become to be known as an air lift.

Through the introduction of air into water, the bubbles cause a vertical current.

If you stick those bubbles in a tube, you create something of a pump.

An air lift in an aquarium is mainly used to create current and keep the top surface of the water moving. This top surface is exposed to the oxygen in the air, and the exposed water gains dissolved oxygen, or DO,  essential for the ongoing good times, and life, of the fish in your aquarium, or aquaponics system.

I don't have an air pump, because I run so much water through my pump, that it's not necessary. I do run a powerhead, which is a lot like a little outboard motor, that achieves the same thing, and in my case is totally unnecessary because, as mentioned, I pump so much water with my over sized pump.

An air lift, and a powerhead both move large amounts of water for a small amount of energy. My 5000L pump was 150 watts, my 5000L powerhead is only 13 watts.

The difference is the pump could lift water 5m, and the powerhead cant really lift water at all. All it can do is stir it.

An air lift can lift water, but it's a bit limited in how high it can lift it. It would be nice if an air lift could lift air to a greater height, because then we could create a really low energy aquaponics system in a conventional (grow bed above fish tank) arrangement, and still get the desired flow.

To this end, I drew this.

Normally a picture might paint a thousand words, but this is a picture of particular poor quality, so I'll need to add a few to make it paint up to around 150.

Picture a pipe with some chambers, all sealed and air tight, so whatever pressure is in there, stays in there.

If the air lift were to deliver it's water to a chamber, the water and air would separate.

If the air was then bled off from the chamber, and re-introduced under the collected, chambered water, it might be reused to create a second or third (etc) air lift.

This might mean we could lift air higher than with a normal air lift.

I have no idea if it would work, because I haven't been able to rope anyone I know who runs air in their system into trying it yet.

If I cant get anyone to test the idea, I'll have to buy an air pump.

Either way, I'll let you know if it turns out to be interesting.



120 things in 20 years, bringing you the vaguest suggestion of science in the hope that someone else will do the actual tests and see if my aquaponic, new air lift design actually works.

Aquaponics - Pump rebuild ver 2.0

Only 26 hours after showing off my pump rebuild version 1.0 to international aquaponics legend TCLynx, my pump started screeching, then ground to a halt.

It used to look like this.













The two bits of wire coming from opposing sides support the shaft because...

1. It's a shaft from a different pump and doesn't fit

2. Because it was a loose fit, it wobbled around all over the shop and caused a great deal of wear.

So you could describe my pump as "having seen better days".

A lot better days, and a lot of better days.

Its been running for years in an aquarium, then spent a few years in a shed, then got re-deployed into my aquaponics system.

Soon after It's re-deployment, I had to buy a new impeller. The impeller is the bit that spins around and shifts the water.

A few weeks after that I had a look at it and found a lot of wear on the front bearing.

That's why I originally put the wire in place to hold the shaft from wobbling.

So as a result of all the screeching and grinding to a halt, I pulled it apart and found what may well be the thing causing all the problems. 

It's possible the shaft is no longer within original design specs due to what may be some wear.

Interestingly, there is no sign of wear on my stainless steel wire loops. Perhaps the designers never intended it to be rebuilt with wire.

The pump's shaft looks like this.

The black plastic attachment on the shaft sits at the back of the pump in recess.

An impeller fits over the shaft, and this fits into the pump.

A face plate clips over the front, and this provides the front support for the shaft.

Or should do.

Once it started wobbling, the plastic wore out within weeks.

My original repair worked, but now that the shaft is worn, I think it requires support over a larger length.

Remembering my hand made screws I made for my fishing lure eyelets, I figured I could make a sleeve to act as the front support out of yet more stainless steel wire.

I found a rivet with a slightly larger diameter shaft than the pump's shaft, and added a few coils of my stainless steel wire.

Trimmed the excess.

Leaving me with a convenient sleeve on a wire.

Then neatly installed the sleeve into the front plate using the wire to wrap around the pump, and stop it from falling out.

The project was rushed a little because I had no water flowing through the aquaponics system, but I had it finished within an hour and 15 minutes from when the pump stopped to when the water was flowing again.

I even managed to increas the flow rate from the 70LPH or so it was flowing at a few days ago as seen here...

To a new and improved 135LPH.

Not a bad result.

I have a new pump on the way, but I really need this one to last until I take delivery of it. 

It would also be nice to have this one still running so I have a backup if the new one fails at any stage.

I love wire.

.

Aquaponics - Calibrating a new bell siphon

This post assumes you know something about bell siphons, and roughly how they work. It also assumes you have made one and want to get it to work. If you need a bit of an introduction to this device, it might be worth reading this post first - aquaponics - bell siphon

With anything that you are trying to calibrate, whatever it is, the most important thing to do is make sure you are changing only one thing at a time. 

It's possible to make a bell siphon work with all kinds of different approaches, but in its simplest form the standpipe drops straight down from the grow bed, and the water flow isn't interfered with in any way

By having your standpipe drop straight down into air the only thing you can change is the flow into your siphon. The easiest way to do that is to put a tap on the inflow to your grow bed, or a tap that diverts some water away from the pipe going to your grow bed, and dumps it straight back into your fish tank. Plastic taps cost about $2. Don't use a brass or galvanised iron one or anything metal because it might poison your fish.

Turn the single outlet from your pump into two by adding a T-junction between the pump and the grow bed.

Make one of your two new outlets go up a bit higher than the other. This one is your excess overflow, and needs to be diverted back to your fish tank. The reason we make it go up a bit higher than the other is so that it becomes the lest preferred way for the water to travel. Water hates traveling uphill, so it will prefer to go into the lower pipe with the tap attached. Only when the tap is turned off a bit will water flow through the higher pipe, and overflow back into the fish tank.

The other outlet gets the tap, and continues on to the grow bed.

before you start...

- make sure your breather pipe is 2cm away from the bottom of your grow bed.

- make sure the breather pipe is breathing fresh air when the water is low enough. Its possible, if the breather is a narrow enough pipe, and is hard against the siphon, to form a meniscus so that it sucks water even when it is above the level of the water. Check that the breather pipe is sucking air when it should be sucking air.

- make sure the water can flow through your media screen fast enough. If you have a screen made with holes drilled in it and there are not enough holes at the bottom, the flow through the media screen can reduce as the tide goes out. This can make for false stops. When the siphon stops, the sudden small amount of water that flows back out of the bell can create a localized increase in water depth. This can reseal the breather, and also kick off the siphon again if it hadn't completely stopped.

Steps in tuning your bell siphon might be (for a tap that is at the end of the pipe to the grow bed)...

1. turn on the tap to a midway position.

2. wait until the water gets to the top of the bell where it should trigger.

3. if it doesn't trigger turn up the tap and go back to step 2. If it does trigger wait until it empties.

4. if the siphon doesn't stop when the grow bed is empty turn the tap down a bit until it does.

5. wait until it fills and see if it triggers properly at the top. If it does, watch it cycle way too many times, drink beer and bang on about it to your friends (I recommend a glass bell siphon to this end). If it doesn't, adjust the tap so the flow is reduced a tiny bit and repeat.

The object here is to adjust the flow in ever smaller amounts until you narrow in on the correct flow. Once achieved, the flow should start within a few seconds of the first flow of water from the standpipe, and should stop quite suddenly. It will probably take 4 or 5 cycles to adjust.

If you still cant get it to operate, there is a fair chance your pump and siphon don't match. Try adding an inner sleeve to the standpipe to reduce its diameter.

Trouble shooting siphons

Any air in a bell siphon should just exit down the standpipe as the water rises and the pressure inside the bell increases. If it doesn't, then there is a fair chance the exit pipe isn't draining freely. With air in the bell, it's possible that your bell might float, and not trigger.

Some people say its a good thing to have some water in the exit pipe, but after a stack of experiments, I found that even though having some water in the pipe often fixes a problem siphon, a bell siphon will be much more reliable if you have a clear, straight down exit that is flowing into just ambient air pressure. That is, dump from your standpipe into fresh air, then catch the water in a drain to take back to your sump, or just drop it straight down into your fish tank if that's your arrangement. At the very least, make sure your drain is running downhill all the way to the end. It makes it a lot easier to get the flow right if your are only dealing with one variable.

The more simple your system is, the more reliable it will be.

Getting your flow right is a much better solution than adjusting your drain by putting bends in it, adding uphill sections, or submerging the end. All of these things can get a siphon to work that otherwise might not, but dumping to ambient air pressure, and adjusting the flow until it works, will make for a very reliable siphon because this makes for only one variable, and with a tap, you have total control over that one variable.

Keep your system simple, and it will reward you with reliability.

Aquaponics - Puddle flange

Who would have thought there was a need to call something a "puddle flange"? It turns out there is such a need. In fact, I just bought one.

A flange is normally a thing that flares out from the size of a pipe, to something at right angles to that pipe.  It allows you to connect it to another flange with bolts.

Puddle flange

A puddle flange is a PVC something, that flares out from the size of a pipe, and connects to a puddle.

It turns out, the thing you have in your shower around the drain is a puddle flange.

I found one that has a hole in it that perfectly fits a 50mm PVC pipe.





I'll stick a 50mm pipe into the hole to act as a standpipe, and silicone the puddle flange into the hole that's in the bottom of my new grow bed.

Because I bought a pump with expansion of my system in mind, it's too powerful to need to run it 24/7. I'll be putting my pump on a timer, and running it for perhaps 10 minutes per hour. This means I will probably settle on using a slow leak approach rather than bell siphon approach to drain my grow bed.

The slow leak approach will involve putting a hole in the bottom of the standpipe, just up from the bottom, so that in time all the water will drain out. The standpipe is there as an emergency overflow pipe.

If for some reason the water fails to drain out of the grow bed, on the next cycle, the grow bed might overflow. With a standpipe as an emergency overflow, the grow bed might remain flooded, but the water will overflow back into the sump.

I'll drill a small hole in the standpipe to start and see how long it takes to empty the grow bed. If I need to, I can then drill larger and larger holes, until the grow bed drains over the space of about an hour.

I'll also be setting the drain up so that if at some stage I need to change the system to a bell siphon based one, all I'll have to do is replace the standpipe, and add a bell.

Aquaponics - Inverter based electrical backup system

We get a lot of blackouts.

Fish hate blackouts.

I'm going to blackout proof my planned, larger, aquaponics system by building an electrical backup. I also need to build my planned, larger, aquaponics system.

Here's what I've done so far...

Attractive isn't it.

I happen to own a one hundred amp hour deep cycle battery. That's it in the bottom right corner of the picture.

I also own a multi-meter, a battery charger, a powerhead, and a bucket of water. 

As of today I also, also own a 200 watt inverter. It's a device that turns 12 volt battery power, into mains power. I had to buy it. A small inverter doesn't cost much and you can pick one up online, or in camping sections of department stores.

A power head is essentially a fish tank stirrer. It aids in supplying the water with oxygen, and will also create a bit of a whirlpool to concentrate fish waste solids into the center of the planned, larger, fish tank. This will allow the solids to be extracted from the fish tank, and moved to the planned grow bed where they belong. 

The powerhead is a critical component, because I'll be relying on it to supply oxygen to my fish in case of a power outage or pump failure. That's the powerhead in the blue bucket. It's basically just a small motor with a propeller on it. According to the box it came in, it moves 5000 litres of water per hour. The best part is, it moves all that water with only a 12 watt motor. My pump also moves about 5000 litres of water, but it has a 150 watt motor. 

The pump's main purpose in life is to supply the grow bed with nutrient rich water, but the bacteria will be fine for a couple of days if it fails. A system full of fish on the other hand, will start to suffer within an hour or so if the water isn't moved around.

I'll run the pump on a timer, so that it runs for around 10 minutes of every hour. I'll run the power head all the time.

The plan is to run the powerhead from the large battery, via the inverter, and to run a battery charger to keep the battery topped up at all times. Based on the tests I'm currently running, and on my rough calculations, in the event of a blackout, I estimate the battery should last approximately forever. 

So far I've been running the powerhead for 4 hours using the battery alone (ie without the charger), and the batteries capacity has actually increased. Which is odd. I'm guessing it has something to do with the day warming up, which might be changing the battery's abilities. 

This electricity stuff is really the kind of thing I should know something about. Perhaps I'll look into it.

Aquaponics - Success

Success! I've actually managed to out-smart my fish. This last thwarter was made from a plastic mesh designed to keep leaves out of your gutters.

It's a good thing I'm learning on my small blue barrel system. I'd hate to be making all these adjustments on, and drilling holes in, my big system.

I just spent an hour trying to get my auto siphon to work again.

In order to prevent my fish tank from getting too cold overnight, I tried turning off the pump during the hours of darkness (I now have a small air pump for oxygenation). The downside to this was an increase in ammonia and nitrite levels.

- The nitrates values are divided by 100 so they fit on the graph. (I'm told nitrates can safely be over a thousand, so nitrates are not a concern)

I think my nitrite and ammonia levels are still within safe limits, and it was only for one night, but I've decided to go back to running the pump overnight.

Aquaponics - Pump change

I put a new (to me) pump in the blue barrel system and put it on a $3.99 timer so that now it runs for 15 minutes out of every 90 minutes. A lot of people in aquaponics seem to do this. This is because it pumps so much more water than the other one did. I'm not sure how it will go when there is fish in because I'm not sure if that will be enough oxygenation. I'm not sure about some stuff sometimes. I also have an old aquarium air pump, so that might come into play to solve the lack of oxygenation issue.

It looks like the system is cycled and running steadily so its time to get some fish!

Aquaponics - New pump and powerhead

My old pump looks like this. Yes those opposing wire loops I added are in fact the new front bearing. This is the pump thats been running for the last 45 days in the small blue barrel test system.

I took delivery of the new pump and powerhead. This is for the second, larger aquaponics system. The pump is the big box and the powerhead is the small ball shaped thing on the top left.

The pump will shift 5000 litres per hour at zero head. That is to say if all you were using it for as a stirrer it would shift 5000 lph but if you want it to move water uphill, the amount of water it can move tapers off depending on how high you are trying to move it.

For some crazy reason not all pumps tell you how much they can pump at any given height. This one only tells you that it can pump to a maximum head of 5 metres. That means you will get 1 drop per hour at 5 metres . From what I'v read and seen, at 2.5 metres you can expect a bit less than half of its maximum output. So I'm hoping this one will pump around 2500 litres per hour at 2 meters head. It might turn out to be a bit more than 2 metres so I made sure there was plenty of excess. I hope. All I need is 1000 litres per hour so It shouldnt matter.

The pump is 150 watts but will only run for a few minutes every hour. The powerhead on the other hand will run all the time in the fish tank, but is only 12 watts even though it also moves 5000 litres per hour. The powerhead cant lift water at all and is there only for its ability to stir water to aid oxygenation. The powerhead's other function is to create a slight whirl pool which will make solid fish waste gravitate to the center. Once there it will be picked up by the overflow outlet. and piped to the pre-filter.