Aquaponics, Food for a Hungry World

Aquaponics, Food for a Hungry World - I spend a lot of time thinking about this, although I won't be doing anything physical on it until next year. I am not writing this blog for anyone else - just me! I don't mind if no one else reads it at all, but it helps me to keep a record of my progress and my thinking.

But if you do decide to read it, feel free to comment!

Saturday, 28 May 2011

Garlic Spray

I looked at my one tomato plant in my greenhouse today, and was surprised and annoyed to see signs of blight - so early in the season, and after so little rain. So I decided to try mixing a garlic spray. I used most of the very small garlic cloves from last year's harvest, mashed them with a pestle and mortar, and followed the instructions - halving the quantities. I still have over 2 litres of the stuff left, and the recipe says it must be used fresh! Also my house stinks of garlic!

Whether it will deal with the blight or not remains to be seen!

16th June: It Works! After removing a couple of slightly blighted leaves and spraying with the garlic, there have been no further signs of blight! Next question - can the liquid be frozen and keep its fungicidal properties?

Wednesday, 18 May 2011

Fish Stocking Levels

I have found a lot of very useful information at The Aquaponic Source. In particular, though, I was looking at fish stocking levels, and found an apparent difference between the advice from Murray Hallam and the advice from Sylvia Bernstein, so I emailed Sylvia to get some clarification. These two ‘aquaponistas’ bridge the gap between Australia and the US, and Sylvia explained that there is no difference in the two sets of advice, one being based on numbers and the other on weight. I watched Hallam’s video (the short version) again and realised that his ‘1 fish per 10 litres’ refers to fingerlings. Problem solved.

I have often noted that aquaponics is not a popular practice in UK. In my search for information, I have not found a UK centred aquaponics book. (perhaps Stirling University could look at filling this gap!) What I did find, last time I checked with Amazon UK, was ‘Aquaponic Gardening: A Step-By-Step Guide to Raising Vegetables and Fish Together’ by Sylvia Bernstein, and having browsed her website, The Aquaponic Source, extensively, I realised that this is probably the most useful book I could find on the subject although it is based on US practice. Sylvia was surprised when I told her I had ordered it as it doesn’t come out until October! But I have pre-ordered it and will have to be patient!

One reason I have for looking at stocking levels in particular is because I have seen a house where I may end up living, and there is slightly less floor space than I had hoped for. The situation would otherwise be pretty good but I have to work out how to fit in my aquaponics project – hence the calculations! But I am sure it can be done!

Wednesday, 11 May 2011


I followed up the rhubarb pesticide question with the website where I found the recipe. This was the emailed response:

I would imagine that a high enough concentration of rhubarb leaf pesticide in a small volume of water could harm fish but in a garden-pond scenario with a small dose that there would be little risk. However, by avoiding spraying the pesticide into the water itself you will avoid any risk to the fish.

di Jonathan Radford

So I guess that used with care, it should be OK.

I have received the brochure and a sample from the Keder greenhouse people, CLM. They look like everything I could want, but the prices are high enough to contract the sphincter muscles! I shall have to downsize my expectations – or possibly live in one! But they look fabulous. Exactly what I need.

Pest Control!

The issue of pest control in organic gardening becomes even more important when considering aquaponics. Will the pest control used harm the fish? Will it make them inedible? What pests might harm both plants and fish?

Apparently snails and birds must both be kept away from the fish, as they may carry parasites which can also attack fish. Does that include slugs I wonder? What if you feed a slug off your lettuce to the fish?

I found a DIY aquaponics unit on Youtube where the legs of the grow-bed stand were stood in containers of water to avoid slugs climbing up. It seems to me that it would be wise to prevent access to the unit for slugs and snails, and under cover, birds should not be a problem.

There seem to be a number of pesticides which can be made from plant extracts, and the most widely spoken of is garlic, which is suggested by Murray Hallam in his DVD. Another is rhubarb leaf, and I am still trying to establish if this is harmful to fish. My new best email friend Charlie, at Aquaponics UK, also mentions elder, and chilli. I quote here his responses to my email query about the use of rhubarb.

I also notice frequent mention of soap spray – with the warning that it should be ‘soft soap’, e.g. washing-up liquid, not detergent. This seems to make life difficult for aphids, as well as enabling any pesticide to stay on the leaves.

Of course we should never forget that all this produce is to be eaten by US!

“Hi Tim,

I’m afraid I’m not sure (even though 6 years of my PhD research was focusing on aquatic ecotoxicology or replacements to organophosphate pesticides), i don’t have a scoody doo, I’m afraid.
i have made formulations with rhubarb and elder which both worked great, but i have only used them in soil... but I’d be very interested to hear how you get on, please keep my updated...

Garlic, and soap sprays are well proven options... and ones we use with good effect, but you make reference to a Keder house, so I’d suggest making sure they don't get in and if they do, then establish a healthy population of beneficials... “

“Yes, we've used garlic, chilli, and soap sprays and they have been fine, ultimately it’s a foliar treatment and providing the surface area of your growbeds, if media, is not wet, which it shouldn't be, then any active ingredient should volatilise before it’s an issue.. if indeed it would be in the first place, similarly with rafts.
I would think it would be fine, and next time I get a pest issue, I’ll definitely try it... and keep you posted too

best wishes

Monday, 9 May 2011

Why Aquaponics?

While visiting my dear OzEarth friends in Holland, for the last time before they move home to their land in Tasmania, I was able to watch Murray Hallam’s DVD on Aquaponics, and I was hooked!

I have been concerned for years at the bizarre fishing policy of the EU, the wastage of good fish and the shortage of the popular species like cod; and as a fan of fish for food, I have been annoyed to find that I can’t afford to eat fish very often!

Another concern of mine, as we lay tied to life’s railway tracks, watching the approaching trains of climate change and peak oil, and wondering which will hit us first, has been the prospect of increasing food scarcity globally and the increase in food costs locally. To that end I have been growing much of my own food for a few years.

However, I am now at a turning point. As I become victim of the inevitable physical restrictions of advancing age, I have decided to make some changes. So I shall sell my house, and provide my son with a deposit for his house purchase from the equity. In return he will provide me with some minimal living space – perhaps a static caravan or granny annex – and some garden space. It is my hope that I shall be able to set up a small aquaponics unit, providing vegetables and fish for the family, possibly selling any surplus over the garden gate, and, after a learning period, running one-day courses for other people who might want to do the same.

That decision taken, I am now at the research stage (as well as the renovation stage, to bring my house up to saleable standard!) and to that end I start this blog, for my own benefit, to record the stages of my learning process as well as listing useful links on the subject of aquaponics.

What has become clear is that in UK this is very much an embryonic discipline. Most home aquaponics practitioners, as well as experts like Will Allen, are in the United States. There are a few in Australia, home of the inimitable Murray Hallam. There are almost none in UK, with the only link to expert advice I have been able to find being Aquaponics UK in partnership with Stirling University.

So, not being able to start doing it yet, I have been reading, and trying to get answers to questions: What kind of fish? Where can I get tanks? What type of system should I use? Should it be under cover? Endless questions, which in turn lead to more reading and then more questions.

My conclusions so far are these.

I would prefer Tilapia, because they grow quickly, they tolerate fluctuations in water quality and they are omnivorous. Carp – don’t fancy them! Barramundi – they eat each other (don’t blame them – they are very tasty)! Trout – they take 18 months to get to plate size.

So, Tilapia: on the down side, they are rather prolific breeders (although this can be dealt with in two or three different ways) and they need warm water.

Now as far as I am concerned, the warm water can be used as an advantage; this I discovered from The Polytunnel Handbook. Some people (including Will Allen by the way) use water as a means of stabilising the temperature in a polytunnel. If you have a polytunnel with a tank of warm water, it will dramatically increase the length of the growing season, with some vegetables growing all year round.

In Australia you can be fined many thousands of dollars for having a Tilapia alive or dead! In the warm river waters of Australia they overbreed and destroy the river ecology. But in our UK climate, there is no risk of that as they can’t survive below about 20°C and flourish at 24°C. Lettuce grows at an optimum temperature of 22°C.

The Polytunnel Handbook
contains many useful hints and tips about types and uses of polytunnels (although aquaponics are not mentioned), and I became aware of the Keder greenhouse. This is a very sophisticated and good quality type of polytunnel, using a double skin covering with ‘bubble-wrap’ type insulation between the skins. They are strong and carry a ten year guarantee. They are also expensive, so I shall have to wait to see if I have enough money to indulge myself when I have sold my house!

What I would say as a summary at this point is that I am very worried about the future of both the planet and the UK. I don’t think that the politicians have come close to addressing the problems. So I want to start the process of increasing the resilience of my family. Of course, at this stage of the game they are pretty uninterested, and not really worrying, but I hope that as our situation starts to deteriorate seriously, they will see the potential of all this, and take sufficient interest to take over the running of it!