From System Pilots

Springtime at Carbeth Eco

With the recent turn for the better in the weather, we decided it was time to head back out to Carbeth to plant and cycle our gutter system. When we opened the polytunnel door, a completely changed sight met us – everything is shooting up! Beautiful purple broccoli, a small sea of dill, and even a few lemons are making their presence known at the moment.

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Carbeth Eco is a hub for sustainability innovation, and they’re testing all sorts of things from optimum wavelengths for plant growth to the soil consistency. But our main focus of the day was on continuing what we had started one cold day in January – our gutter aquaponics system.

We’re starting out with well-established seedlings so that once the system is cycled they’ll be able to absorb the nitrates out of the water for the fish, but we’ll also be starting out some new plants from seed shortly. It’s a good idea to have plants at different stages of growth so that your system maintains steady levels – if all the plants were harvested at the same time, there would be nothing to draw the nitrates out and you could have an algal bloom or a bunch of dead fish on your hands.

We got our hands on some strawberries (Alpine and ‘Cambridge Favourites’), lemon thyme, mint, and peas to start with.

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In the next few weeks, as the system becomes more established, we’ll also try sprouting some lettuce from seed – it would be great to have a whole tray of multicoloured salad greens!

Because the plants came in soil, we had to carefully and thoroughly wash the roots before putting it into the system. This is to avoid transferring any unwanted bacteria that might be living in the soil, and to avoid muddying the water.

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 After that we just slotted the plants in where we want them – as simple as that! We might need to do some rearranging in the coming weeks, but they all have plenty of space to spread out so we’ll see. The mint will no doubt take over soon, but if it becomes too unruly, it can be taken out almost as easily as it was put in, which is one benefit of using the clay substrate.

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Finally, we needed something to kick-start the cycling process. We need to build up the bacteria that will convert the ammonia left in the water by the fish into nitrite, and another that will convert the nitrite into nitrate, which can be absorbed by plants. There are several ways of doing this (in the past we’ve used ammonium chloride), but since Carbeth Eco has a trout pond teaming with all the nitro-bacteria your heart could ever desire, we decided to try seeding it naturally. A few minutes of scouting around the pond, and we were able to fish out a brick from the pond. Unconventional, perhaps, but worth a try!

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The rest of the work for the moment is up to the bacteria. We added a bit of ammonium chloride for food, but we’ll need to wait for colonies of both types of bacteria to develop before fully introducing our fish. We originally planned on putting trout fingerlings in this system because the pond stocks trout, but because of the heat the polytunnel is already generating, it will be too hot for them. However, tilapia could very well be the perfect new residents for the gutter system – stay tuned!

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New Gutter System

Recently we’ve been out at Carbeth Eco quite a bit enjoying the countryside and getting to work in their polytunnel imagining up all sorts of designs. Our most recent one is made out of a large fish tank we found in a skip and some guttering – and not much else!

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The guttering can often be upcycled, but can be bought for around £13 for a sheath in home DIY shops. We were going for simple and effective with this system. We were able to pick up some gutter clips that did the job perfectly:

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While we drilled the gutters straight into the wall of the showcase area behind the tank, a wooden pallet (also easily upcycled, but make sure it wasn’t used to transport hazardous chemicals first) would do nicely for a more portable system. Each row has a slight tilt to it so that the water will flow nicely once the plants have been added.

Image  For this system we decided to have three full rows and a small trough on the bottom, but the gutters could be adjusted to fill as much of the wall as desired. How much area for the grow beds you can use will depend on the amount of water in your tanks, so keep this in mind.

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For the moment we’ve stuck netting on the ends to hold in the clay substrate, but we’re going to get gutter caps instead to avoid unwanted water spillage. We also drained a few holes along the bottom of each of the grow beds rows to aid water flow and avoid too much congestion at the ends. We may need to add more once the system is up and running, but the great thing about this design is each tray slides out of its clips, making cleaning, adjusting, and replacement really easy!

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What a beaut, eh? We’ll be back in a few weeks to add the end caps, substrate, and plants when things warm up a bit. Carbeth Eco has its own fishery, so we’ll be stocking this guy with some trout fingerlings for the moment, making sure to keep a strong flow of water. Stay tuned for progress!

Up and Running

We made a visit to see how our system was doing in Locavore the other week, and are pleased to see things are getting along swimmingly. Both goldfish are growing, the tomato plant is producing fruit, and some fava beans and basil have taken up residence in the other grow beds.

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Photo by Locavore

Here’s a video shot a couple of weeks after the fish were added – thoroughly comfortable in their new home! You’ll notice that some paper was put in back of the tank to lower the amount of sun it gets – this will help control the temperature.

Although we originally planned on cycling this system with ammonium  chloride, we found it difficult to establish a bacterial colony this way. This could have been due to a number of factors, but the algal bloom halfway through cycling potentially had a big part to play in it. In the end, we decided to cycle it using fish, and this proved very successful. While it can be risky cycling with the fish to start, as conditions have to be suitable to keep the little guys alive, in this case it presented the quickest way to get the system up and functional sooner, as significant delays were proving detrimental to the start-up process.

The system still needs to ramp up to its full potential – another couple of fish, and plants in all of the grow beds – over the next few weeks. And hopefully soon we’ll be able to harvest the plants and sell them in the shop with the rest of the local produce on offer! The Locavore system was our first, so there are lots of valuable insights to be gained from it.  We’ll continue to monitor the system to gather data and help Locavore where needed, but in the mean time it’s on to our next project! Stay tuned to find out what we’re working on next…

Stage 3: The Cycle of Life

We’ve spent the past few weeks cycling our system to build up a biofilter. The biofilter is the key to a successful aquaponics ecosystem – it’s the bacteria that turns the fish poo into fertiliser for the plants. The fish produce waste in the form of ammonium, which is then converted by the bacteria nitrosomonas into nitrites. The nitrites are converted by nitrospira into nitrates, which provides a delicious and nutritious meal for the plants.

The cycling sounded fairly straightfoward:

Step 1: Add ammonia

Step 2: Stuff happens

Step 3: Success!

But it’s proving a bit more tricky than anticipated. First we tried to cycle the system using ammonium chloride, which is a powdered form of ammonia. The advantage of this method is that there are no fish or plants at the mercy of volatile bacteria colonies. However, as we cycled over a few weeks the bacteria colonies never really seemed to settle in, and recently seemed to have left us altogether.

So I decided to go for a more hands-on technique – cycling with the first few intrepid fish. Cycling with fish means you don’t have to introduce any outside chemicals into the system, as the fish produce the ammonia themselves. It means you have to keep a closer eye on the system though, to avoid fish martyrs. When I showed up at the shop today though, the system was looking pretty grim – an algal bloom had struck!

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I reckon it was a bit of a viscous cycle: the algae clogged up the pipes, cutting down water flow and leaving conditions better for more algae to grow, which completely stopped the taps this afternoon. The tank is also getting a lot of light where it is, so we’re going to cover up the window-facing side to cut down on sun and give the fish some privacy.

The fish had only been put in this morning, but there was no way they could stay in there. It certainly wouldn’t start things out on the right foot/fin.

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We got them into a temporary abode, changed the water, and cleaned the algae off. The water can sit over night to let the chlorine evaporate (Glasgow’s tap water is actually quite good pH-wise and there isn’t much chlorine in it, but it will still have a bit) before reintroducing the fish to their home. For a more in-depth explanation of the cycling process, check out theaquaponicsource.com.

ImageHere’s the system, sans fish. That trooper of a tomato plant has been there since the beginning. Looking a bit yellow at the moment without any nitrates, but still throwing out a few flowers. Can’t wait to see it flourishing in a few weeks!

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Step Two – Piping and Framing

On an equally rainy Friday, I made my way to Nithsdale Street to assemble the micro-aquaponics system in Locavore. There was nowhere in Glasgow that sold the size of irrigation piping I needed (not yet, anyway…), so I ordered it online along with the connecting pieces. The wood was provided by Locavore, freshly sealed with linseed oil, and the zip ties were kindly donated by a bike shop I stopped into on my way there (thanks to Willy Bains!).

Here is the configuration of piping that I used. 13mm sizing:

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The upper pipe has three nozzles, one for each of the bottle rows. They will slide right into the holes that were drilled into the bottom of the bottles previously. As you can see, it’s just straightforward connecting the pieces. Putting my playschool skills to good use…

Next I attached the piping to a wood frame using saddle brackets, and secured the bottles onto the nozzles with the zip ties. Yes, a few zip ties were lost by messing around with them and zipping them too early. I’m pretty sure that’s the nature of the beast.

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In the neck of each of the bottles I also put a small bit of sponge. This will help regulate the flow and also filter out any large particles that would otherwise cycle back into the fish tank. An old Irn Bru bottle provided the water catchment area to guide the water back into the tank.

I went to turn the system on and…the pump wasn’t strong enough. Womp womp. The tank I got off of Gumtree came with a pump, but it was old and most fish tank pumps are not tasked with pumping the water straight up nearly a metre. After a trip to The Aquarium on Chilsholm Street (just off of the Trongate) and a chat with the very knowledgeable owner there, we got a stronger pump, took it home, and voila! Three healthy streams of water. a sight to behold, if you ask me (video content and quality will improve, I promise. Still, a decent illustration, for those of you following along at home):

Stay tuned for next time, wherein we cycle the system to grow bacteria and introduce plants and fish to their new symbiotic home!

The Beginnings – Grow Bed Prep

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So there I was, tasked with a small-scale model aquaponics system for a local food shop, in a new city. I want to source as many materials as I can from recycled materials and local businesses to try and support local economy. At the moment, unfortunately, many of the materials needed to build the systems aren’t readily available without ordering them online. Hopefully as aquaponics becomes more popular, that will change. In the mean time, I’ll be sure to highlight any local businesses I do find that have a good stock of well-priced products.

First order of business was to source a tank. We decided to go with a tank rather than an upcycled barrel or IBC (Intermediate Bulk Container, more on these later) because of the small space we had to work with, and the way the end product would look. Because this is going to essentially be a window display, aesthetics are important. Also, because of its size, the fish will be ornamental rather than consumable, so we want to be able to see them. I got a 60L used tank off of Gumtree for £30, and went with 6 750mL plastic bottles to match. While the recommended tank to grow bed ratio is usually 1:1 (and can stretch to 1:2 for experienced aquapnicists) the bottle systems I’ve seen seem to stay on the conservative side, so I decided to go a bit rogue with the ratios. If the plants are overwhelmed with nutrients, we could always add new bottles.

So one rainy Thursday, we began our assembly. First order of business was to drill holes in the bottom of the bottles (this will be where the nozzle of the next bottle will go) and in the sides for the plants to grow out of. This proved more difficult than we had anticipated, given that plastic melts with the drill heat, and is generally a pretty stubborn material to work with in cylindrical form. However, we managed to get them drilled without too much carnage and spray-paint the bottom (this will discourage mildew and algae growing in the clay substrate).

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Set to dry on Moody Blues

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Interlocking bottles

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They may look a bit flimsy, but the bottles have held up very well so far. In the future I’d like to get a plastic cutter so that the lines can be a bit neater, but overall they seem to be doing the job. And they’ve got that added rustic element that the cool kids love these days.

Next order of business, piping and framing and pumping, oh my!