Aquaponics - Heat stress

This is a bit of a worry.

It's a 32 degree c day out there and fish tank water is already 30 c. The air temperature in the grow house is 40 c, and we get days of 46 c+ ever now and then.

My first bulk bean experimental planting cup is showing some serious signs of heat stress.

As are the coz lettuce.

The tomatoes on the other hand are loving it, and don't understand what all the fuss is about.












I'm not really sure what to do about it.

I draped some shade cloth over the grow house yesterday, but it actually made it hotter. I think if I leave an air gap it will work, but dark coloured shade cloth touching the grow house roof absorbed a lot of heat.

I think I'll try to add a frame and perhaps a water spray with a temperature probe to start the spray if it gets too hot.

I sprayed some water around and the temperature dropped by around 7 degrees, so I should be able to work something out.

Aquaponics - Raising seeds

My experimental seed raising system started nearly two months ago, and consisted of a small seed raising mini-growhouse with an inch of fish tank water in the bottom.

The little growhouse was filled with plastic cups with holes drilled in the bottom. These were filled with scoria as my grow medium.

For the first two months or so everything semed to grow well. I would just drop the seeds on the top of the media, (except for beans, where I added a layer of scoria over the top) and was seeing around 50% success in germination.

The condensation forming inside the mini-growhouse would rain down on the seeds and keep them moist.


Most of what I was growing was basil, and coz lettuce. As the plants got big enough that I thought their tap root reached the bottom of the cup, I'd move them into my NFT tubes.

The interesting thing was that the water stayed fresh.

Very fresh. No smell and it looked clear enough to drink.

Normally water left sitting for months would sour, but even though the water had fish nutrient  (the water was from the fish tank) it stayed sweet.

Pictured here is what it looks like after three months.

Its still surprisingly clear and still has no smell.











I plant coz lettuce every few days to keep a constant supply, but the last few batches haven't done so well, so I thought I'd inspect the growhouse a bit more closely.

It still looks pretty good, but there are some signs of the water going a little slimy. Keep in mind this is the original water.

It's possible that the slime is rotting the seeds before they can germinate, or perhaps it's just that the nutrient is depleted, but I thought I should was it down and start again.

From now on I think I'll clean it every month or so.

It's no great task to was it, but I wanted to see how long it would last. It seems that the cycle of evaporation, condensation, and dripping rain from the ceiling all within the little growhouse has in some way kept everything fresh.

The brown you can see is dirt on the bottom rather than slime growing or fish solids. Some of the original pots for the basil were not cleaned as well as they could have been.


All in all, it's been an interesting experiment, and I can see no reason why it shouldn't continue to be my way of growing lettuce seedlings on an ongoing fashion.

[Not all seeds took well to it. The baby spinach tended to rot before germination, as did larger seeds like rock melon, although both those seed types came from old packets, so it's possible the method had nothing to do with it]


120 Things in 20 years - where shortcuts and time saving, lazy methods of aquaponics, and raising seeds is a way of life.

Aquaponics - Mini seed raising grow house success

It's well over a month since I wrote a post on seed raising, where I tried my current method for the first time.

I think it's a success.

I planted fifteen cups with perhaps two or three basil seeds in each. From that I got around thirty sprouts with every cup having at least one successful sprout. I'm not sure what the normal germination rates are for basil, but that's good enough for me.

The main advantage is that they are planted directly in the posts they will spend their entire lives in, so they wont get disturbed with transplanting.

I've since removed two sprouts and planted the pots with lettuce, with each one planted about 10 days apart. (a new lettuce cup is in there now to the left of centre) This means that, since the basil sprouted, I've planted, sprouted, and moved out two cups with cos lettuce in the time the basil has taken for the basil to have grown enough to be ready to move.

Here's one coz lettuce I just moved.

There are three seedlings in it, and I'm pretty sure I put three seeds in, so my method seems to be working fine.

I'll probably take the smallest one out, but my experience with three or more spinach seedlings in the one cup says it should be fine. I repeat harvest spinach and lettuce, so the plants never get to full size, but if one get's too big, I'll just harvest the excess and just leave one per pot. Whole small coz leaves make great Caesar salad.

This is another cos lettuce cup I moved ten days ago or so.

The cos lettuce seedlings I grew without covering the seed at all. I just dropped them on the surface, and put the lid on the mini seed raising growhouse. The condensation rain was enough to keep them wet enough to grow roots long enough to touch the water. That's enough enoughs.





It's also interesting that it's the original water in the mini seed raising grow house, that is now around five weeks old with no signs of it going off or tuning green.

So here is my official seed raising guide...




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120 Things in 20 years Seed raising guide 2011        Page 1 of 1  



Put a seed on top of a pot filled with scoria.
Put the pot into a mini seed raising growhouse with an inch deep of fish tank water in it.




                      this space intentionally left blank




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You can print that out and make a calendar with it if you like.


120 things in 20 years. Not just empty space and success with mini seed raising grow houses for aquaponics, but so much more.

Aquaponics - Strawberry towers and NFT tubes.

Success! Mrs 120ThingsIn20Years and I finished renovating the growhouse.

It looks like this.

Sorry for the poor quality photo. It got dark whilst I was having a rest that turned into a sleep.

Rests can do that.

The new NFT tubes addition looks like this, and is mainly comprised of half a dozen holes with beans at the back so I can climb them up the wall, half a dozen holes with coz lettuce in the centre, and half a dozen of baby spinach. There are a few other things sprinkled in between, and where ever they would fit.

The strawberry plants have all been transplanted.

Those that were in my original little test system should have transplanted without stress because they were already in my modular transplanting pots, but it took me so long to finish the redesign that they spent a little time walking around on dry land.

Not happy plants.

The ones I ripped from the main grow bed and transplanted with bare roots, seem to be just fine.

The original system is a wreck. I did a lot of damage moving it around and getting in behind it to tie down the growhouse structure to a fence.

The end result is a bit sad looking, but it will bounce back.

Along the right side, I planted peas that will climb the wall next to strawberry towers, (to right of frame) and the cascading plant at the front left is the oregano I rediscovered in the centre of the overgrown bit under the tomato. Actually there are two tomato plants in that lump, and I damaged the third too close to the roots to save it, so it's now worm food.

Someone from a university is coming to peek at the system tomorrow. I hope he didn't want it to look pretty. Oops. He's looking at lots of local systems, so no doubt he will be used to seeing systems in a state of constant rebuild.

The plants in the back left corner are some flat leaf parsley, and the base of a store bought bunch of celery that I thought I'd plant. It had no roots and no leaves, but It's doing quite well.

Aquaponics can do that.


Not just Aquaponics - Strawberry towers and NFT tubes - http://120thingsin20years.blogspot.com/


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Aquaponics - Fish salad

A fish salad doesn't need to involve eating a fish. Sometimes its enough to just invite a fish to a salad dinner.

Some of my cos lettuce is going to seed, and that means it starts to get a bit bitter.

We repeat harvest our cos lettuce by pulling off leaves as we need them. This means you need a lot less room to get a salad every day, because the root stock is big and healthy, and the leaves you pull off are soon replaced. Repeat harvesting means none of the waiting for all that growing plants need to do when you plant them from seed.

But one nice thing about keeping silver perch, is that they eat all kinds of stuff.

I cut the top off a lettuce and dropped it into the fish tank.

Usually, you don't see any great excitement from the fish, but by the next morning it looks like it's been attacked by a bunch of lazy vegetarian piranha.

Aquaponics - Poop

Common practice is to spread your solids fish waste evenly over the grow beds so as to avoid creating dead areas depleted of oxygen, and perhaps containing too much nutrient for the plants. People often add composting worms to their grow beds to aid in the break down of fish solids. The normal method of distribution, is to split your incoming water into several outlets. This is often done by making a loop of hose that surrounds your grow bed, and drilling holes so water enters from all around.

I'm trying something a bit different. [note from the future - I'm currently engaged in a debate as to this being a good idea or not, so copy this approach at your own risk (even slightly more than everything else of here should be copied at your own risk)]

A few weeks ago I tried adding the water directly to the siphon area. Rather than going through the grow bed media, it just feeds into the gap between the media screen and the siphon. What this means is that the clear water spreads throughout the media, but the solids get dumped back into the fish tank.

Normally, the point is to try to get the solids out of the fishtank, but this way the solids get broken up each time they get dumped back into the fish tank. they just seem to vanish after going through the system a few times. At any time, when you look into the water, there is about the same amount of solid fish waste in the water. It's normally queued up in a bit of a whirlpool that forms near the pump. At any one time there might be a teaspoon of solids and bits of who knows what in the little pile.

It's possible that this will all end in disaster, but it's also possible that this is a viable method of mechanically breaking down fish solids before they do into the grow bed.

Because I'm lazy, it's also worked out nicely that I didn't even have to make anything. All I had to do was extend the pump hose so it would reach the siphon.

There is some chance that the solids are building up on the far side of the media screen (in my case, the soft drink bottle that keeps the grow media away from the siphon) but the water rushes to the siphon quite quickly once it triggers, so I suspect it would draw any solids back through the screen and into the fish tank.

I'm keeping a close eye on it and will let you know if any further developments manifest.

By the way, that's strawberries at the top left, three week old coz lettuce (from seedlings) top right and bottom, and the little ones in the middle are baby spinach (also planted three weeks ago from tiny seedlings). Interestingly I planted the spinach on a hot day in the middle of the day and they all wilted to the point where I was sure none would live. Two days later they were still alive but were all wilted to the point of laying flat on the ground. But now every single one is thriving.

We should be harvesting individual salad leaves within a week.

Aquaponics is like intensive care for plants.

Aquaponics - Grow beds

On day 4 I made life! Pictured is a coz lettuce 4 days after the seeds were sprinkled around.

When you first start running your system you do it without fish because the environment is too unstable. You can do it with fish but have to be very careful to avoid a stinking mess and some major karmic debt.


I'm happy to eat fish (and can cope with any fish deaths that may occur as a result of my eating them) but don't trust my new abilities as a fish farmer, so I'll be doing what is called fish-less cycling to get my system started. That doesn't mean you can't put plants in because, it turns out,  to cycle fish-lessly you add ammonia in some other form, and the entire process works just fine without the fish.. I'll talk a bit more about fish-less cycling in another post.


 A garden bed or grow bed (abbreviated in online forums as GB) is filled with some kind of gravel-like media so the plants have something to hold onto, and so the nitrifying bacteria have somewhere nice to set up house.

It seems plants don't actually like the exhaust that fish put out, but bacteria exist that love to convert it into stuff other bacteria like to convert into the kind of thing plants like.

Fish excrete ammonia, (fish don't like ammonia) some bacteria change that into nitrites (fish don't like nitrites either) and then some other bacteria convert nitrites into nitrates. Plants seem to like nitrates and fish don't hate nitrates quite as much as they hate all that other stuff. This process is known as the nitrogen cycle, and more information can be found here by clicking this.

The gravel that you use depends on how wealthy you are. You can buy clay balls that look nice, are great to work with, and work very well. Or, as I have you can use scoria (some kind of volcanic rock with lots of holes in it). you can also use gravel.

I used scoria (and a small amount of an experimental clay based media I made) because it cuts your hands and is difficult to work with. I'm not very wealthy. It was cheaper and it has a stack of trace elements that should make themselves available to the plants over time. My scoria is also red, most red stuff in rocks in Australia (I'm in Australia) is iron. Plants like iron. Scoria also has a huge surface area because of all the holes and because of its irregular shape, so there should be plenty of space for the bacteria to colonize and lots of cavities to hold water.

scoria looks like this (scoria doesn't always have a key in it)...

- the beasties live in the grow media. They eat fish crap and crap out plant food.
- interestingly a stack of fish eat plants, and those that don't, tend to eat things that do, so the entire thing can just go around and around for ever. Which is nice.

Those bacteria also eat fish food (or at least they eat the stuff that fish food will break down into), so any food not eaten eventually breaks down and gets absorbed nicely into the system (within reason).

By adjusting the height of the siphon's standpipe its possible (and desirable) to set the flood depth of the grow bed. Set high tide to a point just below ground level. I'm told 2.5cm below ground level is about right. Plants don't like to get too soggy and the bacteria don't like light so there is no point in over filling and its just going to waste more water to evaporation if you over fill the grow beds (I'm told aquaponics uses only about 10% of the water you might use on a dirt garden). Its also a good idea not to fill your grow beds all the way to the top with gravel either. Over filling your beds with gravel will end up with you spilling your media onto the ground every time you dig around or harvest a plant.

My grow bed takes around 20 minutes to fill, and around the same time to drain.  The pump runs all the time so water is flowing in the entire time, even when its also flowing out.

As a rough guide your media takes up around 60% of your grow bed leaving space for water in the other 40%.