Aquaponics - My first strawberry

One of the things most important to me in doing aquaponics, was to grow some strawberries. A lot of strawberries. I love them.

Some time ago I bought a selection of different varieties of strawberry to plant out to see which would work best in an aquaponics environment. Sadly only one seemed to thrive, and I have no idea which one it was.

Success! It's now fruiting, and in a couple of days I'll taste the fruits of my labour.

I'm now frantically searching to see if there is some way to clone this plant.

I know that at some stage in their growth cycle they send out runners, but there might be a way to divide up this plant to get a lot more going rather than doing all that waiting.











On a not so successful note, I planted out some seeds a few days ago, and there have been mixed results.

Pictured here are giant white radish.

For some crazy reason, many of them seem to have died.

They look like they over heated, but the weather was far too cool for that. They definitely didn't dry out. The only other thing I can think of was that perhaps the water and fish emulsion tea was too strong, and it burnt the leaves from direct contact.

I'll see if I can water them without getting them wet.

Aquaponics - seed raising

The second, bigger aquaponics system is taking so long I'm scared I'm going to miss all this summer's growing season.

This poor little test system is looking a little crowded as I try to get as much as I can from it to keep us supplied with salad greens and long stemmed broccoli.

I really cant wait to get hold of all that new veggie growing real estate in the new system.

In a desperate attempt to have something to plant in it if it ever gets finished, I've set about planting out some seeds in a seed raising tray. I've also planted some seeds in a few other containers.

To try to keep dirt out of my system, I decided I would try to raise the seeds in a course builder's sand available at my local hardware. I have no idea if this is going to work, but if it does the roots should come out with ease, and be relatively undamaged. Because there is no nutrient in the sand I'm watering the containers with water with some fish emulsion added.

One of the great things about aquaponics is, when you transplant something, it springs to life without missing a beat. Even when I plant seedlings that I have handled enough to wash all the store bought dirt from the roots before transplanting, everything seems to cope without all that wilting I used to get in my dirt garden.



It's raining like a crazy raining thing at the moment, but as soon as it stops, Ill make the finishing touches to my new grow bed, then get some gravel.

Aquaponics - Another base for my new grow bed

I think I have finally settled on a base for my grow bed.

And I cut the hole for the puddle flange to the correct size.

I also cleaned it up so I can silicone it. Yes, in my world, that qualifies as clean.

It was necessary to cut away a bit of the wooden pallet underneath as well. This should now allow a clear path for drainage pipes to the sump.







I ended up settling on three wooden forklift pallets, and some bricks to add a bit of extra width. My main concern was to make it strong enough to take the weight of all the gravel, and all that water.

Additionally I needed to make it sturdy enough that if someone taps it with a car or something, it might still be standing the next day. I think my design provides this.

I hope my design provides this.

Aquaponics - fish fed fish

1. When you feed your fish, it becomes obvious that they remember you. Or at the very least remember the food jar they see when you are about to drop food into their world.

2. When I put a 10cm length of plastic tubing into the fish tank to measure my fish against, I noticed the fish would peck at it enough to move it around the tank.

These two points lead me to the obvious conclusion that I need to make a fish feeder that the fish themselves control.

I can trust them.

If I can make some kind of lever that sticks down into the water, and connect that to a motorised fish feeder, I should be able to teach them to feed themselves.

I should be able to train them by waiting near the lever, and when they get near, press the lever for them. I'll set it up so that the feed drops right next to the lever to encourage an association between lever and food.

Once they start hanging around in roughly the correct area, I'll reduce the distance so they need to get closer before I trigger the lever for them. I'll keep reducing the distance gradually until they have to be right up against the lever before I trip the lever.

If I stay disciplined, and don't cave in and feed them even when they are miles away from the lever, I should gradually see them getting closer and closer to the lever whenever they are hungry. They should also start to hang around the feeder, rather than swimming toward me whenever they see me.

Waiting until they get nearer and nearer each time should get them used to the idea that food comes from the lever area.

When they are regularly hanging around the lever, I should be able to stop tripping the lever for them and just wait until one of them hits the lever either by accident, or because fish just peck at stuff.

Once one of them has the hang of it I'm convinced many more will pick up on it.

I'll still have to regulate the food supply so that no more than my system can process is fed to the fish in any given day. This should be possible by only putting a day's worth of food in the hopper. With regular testing of the water, and keeping an eye on how much they take, I should be able to work out if I can trust them with ever increasing amounts of food so that perhaps I could set up the system with enough food to last 3 days or so. I would want to set the maximum amount of food in the hopper to a level that even if all of it got dumped into the system all at once, the system would still be safe.

Now all I need is the device, and a willing fish.

Aquaponics - New growbed stand

Trying to level something that's going to weigh three or four thousand kilograms turns out to be worth getting right the first time.

I started making some kind of base for my new grow bed, but have suddenly become overwhelmed at just how much this thing is going to weigh. Trying to shovel three tones of gravel out of a gigantic bucket would be a tough task, and one that I'd rather no have to do.

The plan is to use at least three forklift pallets. I'll rest them on some bricks to both raise the overall height, and by using different sized bricks, help level the site.









If all goes well, before I add the gravel I'll brace the walls with some cable.

There are two pairs of holes a third of the way from the ends of the grow beds. I presume they were made for creating some kind of brace.

My plan is to thread some stainless steel cable through each pair of holes, and attach the ends to a wooden brace to spread the load, and stop the cables cutting through the grow bed.




Plans have a habit of changing around here.

Aquaponics - Slow leak drainage system

Rather than running a siphon, because my pump is much bigger than it needs to be, I'm going to try a slow leak system.

I'll set it up so a bell siphon will work in it if I ever add another grow bed, and my pump needs to be on all the time. But right now my pump only needs to run for around 10 minutes per hour to turn over the water, and fill the grow bed.

click to play animation if it's not already playing

A slow leak system has a standpipe with a hole in the bottom. It also has a high inflow that fills the growbed faster than the small hole in the bottom of the standpipe can drain it. This means that the growbed would overflow if not for the standpipe. The standpipe allows excess water to overflow back into the sump tank, or fish tank. The height of the standpipe sets the maximum depth of the water.

The timer is simply any digital timer with a power point. You plug in your pump, plug the timer into household power outlet, and set when, and how often you want the timer to trigger the pump.

The aims are twofold.

1. To turn over 100% of your fish tank's water every hour (for the sake of your fish)
2. to fill the growbed to its maximum height at least once per hour, and have it drain back out again before re-filling (for the sake of your plants, and the nitrifying bacteria)

In my case, I estimate I'll be running the pump for around ten or fifteen minutes per hour, but that might require some adjustment after taking some water tests. It's difficult to estimate how much water my pump will actually shift in ten minutes, because I'm not exactly sure how high it will end up having to pump. The higher it's pumping, the less water per minute it will pump.

If this turns out to not work as well as I thought it might, I can always revert to a bell siphon, by simply replacing the standpipe with one that doesn't have a hole in it, and adding a bell.

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 - New grow bed

Scoria has always been the media I favored because its perfect for aquaponics. I'll be using road gravel.

Here's some I prepared earlier.

Pictured here, and using chicken feet for scale, is a  path in my back yard. It's the same stuff I'll be using in my new grow bed. It's sometimes called blue metal, and in this part of the world we mix it with tar, and make roads out of it.

Scoria is great in all kinds of ways, but it's hard on the hands, and because of it's sharp edged irregular shape, it's actually difficult to dig into.

My new grow bed is big enough that I don't need to worry about the extra surface area scoria would provide. I'll get around 2000 - 2500 litres of gravel to fill it, and I'll use the existing system as a pre-filter to seed the nitrifying bacteria.

In a former life, this new grow bed of mine was an abalone growing tank used in aquaculture. As soon as I can stop switching between plans, I'll bu using it to grow veggies.

Aquaponics - Silver perch underwater

A front loading washing machine makes fish more visible.

I salvaged the door from a broken front loading washing machine, and suspended it over my fish with the camera sitting inside it. Camera washing machine goggles allow me to see my silver perch underwater. After seeing the results and being able to see the underwater component of my aquaponics test system, I'll definitely be incorporating some kind of porthole into the lager system.

I turned on the powerhead, and pointed the camera where the current was strongest. The fish seemed to love the strong current and spent much of their time in the full strength, rather than taking cover behind the pump at the other end of the tank where it was relatively calm.



While I had the camera outside I thought I'd try to measure my fish. I dropped a 10 cm length of plastic pipe into the fish tank so as to get some idea of their growth rates. And after photographing the school next to the pipe, was surprised to find I actually had eleven. I thought I had nine.

The smallest is still only around 7.5cm and the largest is around 15cm.

I think they might have been much larger if not for the stress they were put under from the poison plant, and the fact that whenever I lost a fish, I would stop feeding them for a day or two, then feed them only a little for the next week. It's standard practice to stop feeding the fish when anything goes wrong in your aquaponics system to ensure there is no extra pressure put on the fish from nitrite or ammonia spikes. Often a fish death can increase your levels of ammonia and nitrite to dangerous levels, so feeding the fish can just add to your woes. It doesn't harm the fish, and potentially can be of great benefit.

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.

Mold making - My first casting

Casting is the process of sticking stuff in a mold and creating a copy of the thing the mold was originally made from.

I'll be using hot glue from a hot glue gun.

I spread a thin layer of soap over the mold to allow the mold to release. Using glue in something you hold pressed together for a while is perhaps a dodgy plan, but hopefully the soap will prevent it's sticking.

I filled both halves of the mold with glue, then pressed them together.

There was a bit much glue, and nowhere for it to go so the glue overflowed between the two halves of the mold.

In future it might be worth drilling a small hole to let out excess glue.

Other than that, it seems to have worked.

The excess was easy enough to trim with scissors.

Leaving a pretty good copy of the original.

Pictured is the copy after it had been heated with a flame to smooth it out a bit.









There were a few lessons learnt here.

a. If there is nowhere for the glue to escape, it attempts an escape between the molds.

b. If you try to mold hot glue in cold molds, it tends to set a bit too quickly mefore you can press the molds together properly.

c. a, and b above mean the copy can be taller than the original as the molds didn't press together completely and there was a gap. The resulting copy was taller than the original by the thickness of the overflow that had to be trimmed with scissors.

All in all a successful experiment.

Mold making - My first mold part 3

Back to part 1
Continued from part 2

I removed the foil and found myself faced with this.

Its a solid blob of set plaster. I looked at it a lot.

There is a slight seam so the plan was to put a knife to the seam and twist, but the plaster its still wet enough that the knife just cuts it. I think it needs to be bone dry and brittle.

From what I've read the drying times vary with the amount of water used in the mix, but more on that later.

I wait.

In a pleasantly surprising sort of way, 24 hours later, the mold came apart.

The plaster had run down the side of the botom mold and stuck to it where there had been no soap. All I had to do was apply enough force with the twisting knife to break the rim that had stuck and it came free.

I need more soap next time. Or rather I need some soap down the sides a bit next time.

Even more pleasant surprise, as the model also released cleanly.

There are a lot of bubbles in the plaster, but I'm reading of some ways to combat that. More on bubbles in a future post.

The roughness visible in the half on the left is a faithful reproduction of the actual roughness of the original.



To round out the trilogy of pleasant surprises, it also turns out that the lumpy bits that were on bottom mold, and their reflection in the top mold serve a very useful purpose. When you replace the two halves, the lumpy irregularities make it easy to align the parts perfectly. Lumpy irregularities turn out to be called "keys" in the mold making world. Keys are often added to aid in aligning the pieces of a mold.

Bubbles aside, the mold looks pretty good. It's quite an interesting thing to crack the mold and remove the original model. It's not often we get to see the negative of a 3D shape. Especially one we make ourselves. The plaster does an amazing job of faithfully reproducing every detail of the original.

Back to part 1

Back to part 2

WARNING !!! Plaster can get very hot when setting 

google search for: plaster of paris third degree burns

Mold making - My first mold part 2

Continued from part 1

The plaster has dried to a clinking sound when tapped with a spoon.

My fist step is to unwrap it, and gently prise the lure from the plaster.

Next is to replace the lure in the mold and lubricate both the mold and the lure to make sure nothing sticks to either.

It turns out, that there is some kind of natural limit as to precisely how much of someone else's lip balm you can use on a mold making project.

I'll be trying soap this time.

I built up a new wall surrounding the bottom mold and model.

With all surfaces soaped, and some luck, the top half of the mold will separate cleanly once it's set.

I mixed up a second batch of plaster and water in random proportions.

After stirring for a minute or two, I poured it over the lure, and filled the foil box.








I have no idea if I need to do all this waiting. I really want a result so I'm going to wait until its totally dry but I think I can get away with opening it tomorrow morning.

Even though I'm doing my usual "fools rush in" approach to learning how to make molds, I am actually studying hard in an attempt learn how to do this properly. I've found I understand a lot more of the stuff I'm researching if I've had some exposure to the materials involved. With that in mind, I should be able to make a decent mold.

But this might not be it.


WARNING !!! Plaster can get very hot when setting
google search for: plaster of paris third degree burns

Mold making - My first mold

I decided to use a failed handmade fishing lure as my first mold subject, not because I wanted copies of it, but rather because I didn't care if it was ruined. I'd make the mold out of plaster, and make the copy by molding some hot glue into shape.

I realized I needed some way of suspending the lure in mid air to make the first half of the mold. Last week I made a failed attempt at my fist mold. I used a bed of leftover mashed potato. By pushing the lure into a bed of mashed potato, it should have been possible to make the top of the mold, then turn it over and make the bottom.

This mold is to be in two parts. I figured the approach would be to find the halfway point of the object, build a box around it, and make it sit in plaster to that halfway point. Then when it was dry, I could build up some new walls, and fill that with plaster. The mashed potato method worked, but the old bag of plaster I had didn't. It never set. I'm guessing it was because it had too much exposure to moisture over the last few years. This time I'm all out of mashed potato, so I'll have to suspend it in mid air.

My first step was to coat the lure in lip balm to prevent it sticking to the plaster.

Lacking any telekinetic powers to speak of, my new approach was to suspend the lure a centimeter or so off the ground in a vice.

Next, I made a box out of foil to hold the plaster, and slipped it under the lure.

I mixed up some plaster and water until it looked about right. (I'll work out what the ratios of plaster to water should be when I look into this a bit more)
And poured plaster into the box until the level reached halfway up the model.

After only about a half an hour it was hard enough that I could touch it without leaving a mark, but it still felt wet and cold, so I thought I'd better leave it until it felt totally dry. So leave it I will.

Now the waiting. I'm still not so good at the waiting.

I really need to get better at the waiting.

Continued - part 2

WARNING !!! Plaster can get very hot when setting 

google search for: plaster of paris third degree burns