Aquaponics - Marron

Apparently, marron come in two varieties. Hairy and not so hairy. Cherax cainii (smooth) and Cherax tenuimanus, or Margret River marron (hairy).

fine marron illustration*
Marron are a fresh water crayfish, native to Western Australia. They are a good candidate for farming because they have a good food conversion rate, so they grow well and don't cost too much to feed. They can grow up to a weight of 2 kg but are usually harvested for sale at between 100 to 200 grams at a little under 2 years of age. Marron rank equal to the highest percentage of meat to total body weight for similar under-water walking things.

They are active mainly at night, and are opportunistic feeders that will eat whatever they find. In the wild the majority of the food comes from plant material, small living and dead beasties, and detritus (decomposing plant matter colonized by fungi and bacteria.

They thrive in water temperatures ranging from around 13 deg C to 25 deg C. Water temperatures over 30 deg C will result in deaths.

Marron need a quarter of a square metre of space each when grown in a conventional dam or similar, but it may prove possible to increase the possible population density by using a multi level hi-rise approach, or with the addition of a stack of short lengths of PVC tubing to increase the available surface area, and allow lots of places to live and hide.

In order to grow, marron find a safe place to hide, then spend some time shedding their hard shell. Once shed, they expand into their new softer shell and go back to their normal lives until outgrowing themselves again. They may appear sluggish and generally disinterested in the world when about to shed their shells. If this happens, leave them alone and don't try to cheer them up by feeding them. When changing shells they go off their food for a while, and continued feeding runs the risk of fouling the water. As with all aquaponics feeding, feed only what is eaten right away, and stop feeding if food is left uneaten.

Marron can be grown in tanks or ponds as shallow as 20 cm, but beware their climbing and escaping abilities. Like other similarly shaped critters, they can walk on land and will wonder off in search of a good time if allowed to do so.

Marron don't like the sores they get on their undersides from bare concrete tanks so add something soft like sand, or fill the bottom of their tank with PVC tubing.

Apparently marron like to eat worms.

They also enjoy the type of pH levels found within aquaponics systems, and have a particular fondness for pH levels of between 7.0 and 8.5. They are found growing in the wild in water ranging from pH 6.0 to as high as pH 9.0.

Fresh water is best but they can tolerate saline levels of up to 15 parts per thousand. They thrive in salinity levels of less than 5 parts per thousand, and wont breed in higher salinity water.

*actual marron may have legs.

Aquaponics PVC edge capping

It's now 10 days since I moved the smaller aquaponics test system away from it's poison shrub. The fish seem fine and the nitrogen cycle is in balance.

New system grow bed with split PVC pipe edge capping
My new system is also doing well in that I made some small amount of progress by fitting the PVC edge capping.

Corners were a bit tricky. I didn't have any way to measure angles but came up with the idea of folding paper. I folded a square of paper in half via opposing corners. Then laid one of the unfolded sides along the PVC. The folded side forms, or should form a 45 Deg angle.

It didn't work very well.

But on this very last one, I stacked the two lengths of PVC one on top of the other and cut through both with the one cut. That took way too long to work out.

Aquaponics - New system

I did a bit more to the new system today, and undid a bit of what I had already done to balance out my progress, and maintain my standstill.

many small holes make one big hole
After carefully cutting the soon-to-be-grow-bed tanks in half, and patching holes, its a bit nerve racking to make a new hole for the siphon. I started by drilling holes because I have a drill, and find it much easier to use tools that I have rather then the imaginary tools on my wish list. The imaginary ones always go blunt too quickly.

not so round

a bit round


Next I decided the black poly pipe capping I made from all that poly I like to horde wasn't going to be good enough, would look too tatty, and have fractionally more sticking up bits willing to catch on gardening clothes than I normally enjoy. Given that I'm planning to be gardening with this grow bed for years, I thought I might do it properly. Tomorrow I'll get some PVC conduit to cap the grow bed edges with.

When growing produce with aquaponics, you don't really need gardening clothes.

Aquaponics - Externalized sequencer

From time to time I need to empty my head of all the luggage I carry around in there. A while ago I did just such a thing when this idea came out.

This is the second design (here is the first) of mine for a grow bed flooding sequencer. The aim here is to fill each grow bed in turn so as not to empty the fish tank and leave your fish walking more than they like.

Picture an inverted rotating lawn sprinkler with all but one of its arms cut off and blocked. Mount that over a bucket,with a drain going back to the fish tank, and a pipe for every grow bed you want to fill. The drain is to catch the bit of water that misses the tubes, as the sprinkler arm is moving between tubes, and to catch any small leaks the sprinkler has  from the moving seals.

The aim is to have it rotate from one tube to the next, stopping for long enough to fill the grow bed that's connected to each tube. The grow beds take it in turns to get filled, and as one is filling, another (or others) are emptying back into the fish tank.

Make one of these for each tube. The bottom of each tube is connected to it's grow bed and the apparatus is mounted at the same height as the grow beds, so that as they get close to their full depth, the float begins to rise.

When the float rises enough the hook lifts above the point at which it restricts the rotation of the sprinkler arm, and the arm moves on to the next tube.

When you first set it up, leave enough extra length on the downwards bit of the hooks so you can file a bit off to fine tune it to trigger at exactly the correct height. Or you could use a nut and bolt arrangement to make it adjustable.

It should also be possible, to some degree, to accommodate grow beds at different heights by increasing the length of the tubes, placing the floats deeper, and extending the pole that holds the hook.

Feel free to repost these images elsewhere, but please leave the "120 things in 20 years" caption on them.

[edit from the future - There is some additional material on sequencers. Readers might find this newer version in a post titled  The Bullwinkle sequencer build of interest. It's a better design, and only costs around AU$15 to build with off the shelf PVC components]

Aquaponics - Overfeeding

When I was even more of a kid, my favorite book was about overfeeding fish. It looked like fun.

Uneaten fish food (not poop)
One of the problems with overfeeding isn't that your fish sit in your bath tub and get uncomfortably large and interesting, but rather that the uneaten food sits in the corner going rancid.

A mature system can handle a certain amount of excess food as it breaks down into plant food via the normal nitrogen cycle. My grow bed media is kind of mature, but my water is almost all new from a few days ago when I moved the system.

Most of the nitrifying beasties live in the gravel, but I think there are some living in the water, the slime layer on the sides of the fish tank, and on things like my pump, and pump inlet screen etc. This can mean that, after an upset like a washout and water change, the system might not be quite as capable of turning ammonia into nitrates. I think.

fish so well hidden you cant really see anything
When I changed the water and location of the fish tank there was some inevitable stressing of the fish. Shown here is an image depicting not really being able to quite see the fish because they are still hiding.

As a result of the upheaval, they went off their food.

I think the amount of ammonia introduced into the system by feeding should be similar regardless of the fish eating it or it rotting in the corner, but because I had the option of removing the uneaten food, I removed it.

why do chickens have to stand on whatever you are taking a photo of?
A few days ago I finally tracked down a product I remembered seeing in the shed when I was a kid. It's a siphon for fuel etc, but it has a squishy hand pump so you don't need to drink so much petrol. I thought it would be perfect to vacuum up any uneaten food.

It wasn't.

It didn't work very well at all. That might be why nobody sells them any more.

Aquaponics - Overflow

I clawed my way out of my sickbed at the crack of noon today to discover my fish tank overflowing.

Growbed on top of fish tank
My new aquaponics arrangement looks like this.

I think it looks quite neat in its new position and new configuration, but sometimes looks can be deceiving.

Deformation of the fish tank causing a spill
A behind the scenes peek reveals a bit of a problem with distortion.

The existing frame was slightly thinner when turned on its side, and no longer affords support to the side of the fish tank.

The result was to allow the half barrel to deform in such a way as to spill water out. Luckily it didn't spill enough to endanger fish or pumps.

Pumps, like fish, hate it when there's no water overhead. I'm not really sure what fish see in it, but pumps tend to use water as lubricant, and for cooling.

wire holding fish tank in shape
As usual wire came to the rescue. I wrapped it around the entire thing.

wire tangle
I then twisted it into this traditional Australian wire knot known as a "Tangle".

The Australian history of using wire to solve our problems is similar to that of the Swiss in the making of the holes in Swiss Cheese.

I really like the way this camera captures blue.

Aquaponics - Poison plant

It seems I may have been poisoning my fish.

After the last fish death, which also occurred just after rain, I started to think that perhaps the rain was splashing off the surrounding environment and getting into my fish tank through sneakiness.

I looked at all the possible things the rain might be able to occasionally transfer to the fish tank from in a strong wind, and there didn't seem to be much chance of any transfer to the fish tank from anything other than this shrub.

The shrub turns out to be viburnum tinus, and sadly it seems, is toxic to fish.

So right now I'm in the process of moving the experimental system to pastures less green.

At the moment the fish are in a plastic tub, floating in the fish tank,  getting used to their new water, and its new temperature.

I realize this has not been the first time I've felt I had the solution, but hopefully this poison plant might mark the end of the fiasco that has been my first batch of aquaponics fish.

There are eleven silver perch left out of what turned out to be twenty two.

Interestingly, as a result of seeing them in a container, I discovered some are twice the size of others.

Disease fighter

My latest "thing" I'm attempting is to fight off a very bad cold.

I'm not so good at it.

The cold is winning.

Pictured here is the culprit.

Benjamin Franklin:
"People often catch cold from one another when shut up together in small close rooms, coaches, etc. and when sitting near and conversing so as to breathe in each other's transpiration."

Thanks Ben. You could have mentioned that earlier.

Aquaponics - Grow bed patches

One of the problems with taking too long over a project is that I steal all the parts meant for some other project. Sometimes just glimpsing a box full of parts out of the corner of my eye is enough to spark an entirely new project. I'm not starting something new. I've just lost something old.

Before I paint my new grow bed, it's going to need a few less holes. In a past life my grow bed was one half of an upright, square, modular rainwater tank. I'm told fishies dislike the zinc that leaches out of galvanized iron water tanks so they will be sealed in pond liner paint. Being a rainwater tank it has a few large holes cut into it to allow rainwater in.

I cut the side of an old computer box into patches, and riveted them into place with some silicone between for water proofing. I probably didn't need the silicone because the rubber pond paint should seal any gaps, but I don't like leaks so much since my solar hot water project began.

I love rivets and you should as well. Hmmm rivets.

Really, rivets are amazing things because they pull the two surfaces together as they attach. Perfect for this kind of task due to the need for the silicone sandwiching action between the two surfaces.


I wonder if the old computer saw any of this in its future.

Sadly I couldn't find the bell siphon parts I was about to add to this grow bed. After searching for a while I sat down at my desk and realized I had recently used those very parts for the cheese press. So rather than making the bell siphon, I'm off to eat some haloumi.

Aquaponics - Rain pH

Hmmm. This is a pH test of the rain thats falling right now. My test kit only resolves down to pH 6.0, so I cant tell if its 6.0 or lower., but its at least 6.0.

Aquaponics - Hot house

I did a backyard version of an autopsy on the fish that died in the (almost hopeless) hope that the fishy's gizzard would be full of staples, bolts, or something easily identified as the culprit, but it turns out dead fish aren't filled with industrial fasteners, but are in fact just filled with fish guts.

I covered the grow bed in some plastic in the hope that it really is rain that's causing my problems, and also to make an aquaponics hot house. I started with three bent piece of poly pipe (I new all those 5 ft lengths of poly pipe with holes in them would come in handy eventually).

In traditional Australian fashion, I attached everything with wire.

Then covered the entire thing in plastic. I made it so there was no wire on any section that may get condensation running off it. The last thing I need to do Is introduce too much metal into my system. I also made it so that the condensation would run onto the ground rather than back into the grow bed just to be safe.

I got it up just before the rain started. It looks very stormy so I think it was just in time.

The sad thing is, even if this solves the problem, I may have already damaged the gills of my fish. From what I've read, these issues can show up many days down the track.

Even if this doesn't solve the problem with the fish, the plants will love it, and it should keep the system a bit warmer in this stormy chilly weather.

Aquaponics - Keeping good records

I had another fish death today, and it was after some rains. I had a niggling suspicion that the last one died after rains as well. There have been a lot of deaths and I now only have twelve.

I got some data from the bureau of meteorology to check against my records of fish deaths. Unfortunately, and foolishly I don't have complete records of deaths.

I had planned a good news aquaponics story today as the fish were all looking good, and feeding well over the last few days. I thought perhaps I'd put this fish death business behind me, so I figured I'd take some video to show how vigorous and healthy the fish seemed. I didn't notice the dead one. Not so vigorous.

Not recording those previous fish deaths was really crazy. My excuse at the time was that there was no point. It turns out keeping good records is incredibly important. If I had done so, I might now be certain of the cause of all my woes.

Here is a graph showing what I think is a correlation between my potential pH changing events, and my fish deaths. Fish don't like sudden changes in pH and a change can be fatal. Rain could have the effect of lowing pH, but I'm not sure if it could lower it, and then have it recover to normal levels before I did my pH tests. I'm also not certain if a short term change would distress the fish. After all, rain is pretty normal stuff in a fishy world.

B,D, and F all show strong correlations between rain and fish deaths. Rain would have a lowwer pH than my fish tank water.
A shows fish deaths in a dropping pH environment. Not due to rain, but due to the normal action of the nitrogen cycle. G shows the effects of the addition of shell grit to the system as a pH buffer to attempt (successfully) to buffer the system against sudden pH shocks.
C and E show significant rain events that may be responsible for my un-recorded fish deaths. Poor science I admit, but it was around these times that I lost fish, and I'm running out of other ideas. Did someone say "grasping at straws" ?

A,B,D, and F, all show potential pH lowering events. Sudden drops in pH can cause fish deaths. All my fish deaths I have on record strongly correlate to pH drops, or potential pH drops. Thats good enough for me to take action on.

I'll build a cover. It wont do any harm If I'm wrong.

On a lighter note, here is the happy fish video.

Aquaponics - Fish disease diagnostic tool

This fish disease diagnostic website might be useful to anyone raising fish.

Tick boxes describing symptoms, then get a short list of possible diseases, and what you can do about it.

Cheese - So far

So far, I get the feeling its relatively easy to make cheese, it's just difficult to make a particular cheese.

I also get the feeling my cheese making will be seen to have failed two months down the track when I taste it. So it's important to take my cheese making history into account when reading everything I have to offer on cheese. That bit's worth reading twice.

Almost all the research I have done points to really only a few steps to making cheese. Almost all the cheeses have these steps. Sometimes not all the steps, and occasionally in a slightly different order.

  • starting a culture 
  • acidification
  • setting the curd
  • heat treating the curds
  • separating the curds from the whey
  • pressing the curds
  • aging the cheese
  • eating the cheese
There some obvious exceptions to these, say, in the case of the fresh cheeses that are eaten before aging, and might not be pressed. Or even in the case of haloumi where the final process might be to fry it. Mozzarella is another exception where there is a cooking and pulling stage. I might have to make mozzerella, it looks like fun. Then there are cheeses that are dosed with mold as in the case of the blue vein cheeses. But even those cheeses are made with many of the basic steps shown in the bullet list.  

Each different variety of cheese may be only due to a tiny change in the temperature, or a small difference in the amount of pressure used to press it. Some cheese even has two faces, in that it can be eaten as a table cheese in its first few months of aging, and then goes on to be a hard cheese suitable for grating and cooking with as it ages a year or more. 

Making cheese to be aged takes a lot of preparation, a lot of time, and, if you are anything like me, every dish, pan, and kitchen surface you have in your home. It also requires some specialist equipment. Making cheese to be aged for a few months has so far been an extremely interesting, and fun thing do, and I'll definitely do it again once I equip myself better. Then there is also the issue of storage. Where does one store one's cheese for up to a year at 12 deg C and 85% humidity?

My recomendation to the novice would be to make my fabulously successful haloumi.

  • It worked well.
  • It tasted better than anything I've ever eaten in the whole wide world.
  • It was easy to make.
  • It was easy to make the second time (although quite different)
  • It was good value for money.
  • It was relatively child friendly in that it, for the most part, it needed low temperatures.
  • It could be eaten within hours or starting the project, meaning you get to see if it worked right away, and you don't need a storage facility to protect it through it's aging process, and any children involved will not have grown up and moved out before its tasting time. 

If you try it, you will make it again, and again, and it will become an heirloom dish for your family. I promise!

Cheese - Reasonable cheese brining

This part 3 of reasonable cheese will see me treating the outer layer of the cheese to form a skin or rind.

I successfully made my Reasonable Cheese, and eventually pressing it into shape and a cheese-like consistency. The next step was to stop it going rotten. From what I can tell, there appears to be a few different ways of doing this including doing nothing at all, waxing, salting, soaking in brine, rubbing with vinegar, or simply eating it right away.

I chose brining.

First I created a saturated salt solution. I mixed salt into water until I could mix no more. It turned out to be around 200g of salt in 800ml of hot water.

I left it to cool, then added my Reasonable Cheese to sit overnight in the brine.

Ten hours later I discovered a thing that looked a lot like a cheese.

Now I wait. And wait. For between two and six months.

I'm not sure if this cheese worked or not yet. It seems like it may have, but there is no way for the novice to have any real clue as to the success or otherwise of this project for months to come.

This cheese was quite complicated to make and required some specialist equipment. There was a lot to learn, and still is a lot to learn. One major concern I have is the size of the cheese. A small cheese will turn to a small cheese rind before its even ready to eat. I suspect that's why a lot of small cheeses are waxed. ie To prevent them drying out. The first cheese I attempted is already more of a cheese rind than a cheese.

I will make more of this kind, or similar table cheese, but will do so with a great deal more planning and some more equipment. I will also make much bigger cheeses and more of them. I think, to be practical, a batch of cheese would need to be made with more like twenty or thirty litres of milk rather than four litres. There is also the issue of cost. Unless this cheese turns out to be very special indeed, it will have cost much more than it will be worth. Having said that, I am now in possession of the only cheese of its kind. And the last piece of it at that. Effectively an almost un-reproducible, and thus priceless cheese by any standard.

Or not.

Only a great deal of time will tell.

Cheese - Reasonable cheese 2

Continued from yesterday, we saw the curd set enough to get a relatively clean break.

The next step is to cut the curds into dice sized cubes. This doesn't need to be too fussy as far as size goes as the object is just to allow as much whey to escape the curd as possible. Some people use a whisk to gently cut their curds. I used a long knife. Either way, just try to not leave any large pieces.

I then raised the temperature gradually over 15 minutes until it was around 39 deg C, and held it there for an hour stirring gently every few minutes to prevent the curds from clumping.

Some of the cheeses I've read about included a step in their manufacture that involved replacing the whey with clean water for the final cooking. For no better reason other than it seemed like a good idea at the time, I did that. I drained the whey (pictured), then added hot water until the temperature read 43 deg C and held it at that temperature for about 15 minutes stirring gently.

After the 15 minutes the whey got smaller, tighter, and more dense. It sunk to the bottom as soon as it was let off the spoon.

It was time to deploy the "120 things in 20 years whey cool cheese press".

So I did.

I poured off the water, and tipped the curd into a cotton cloth lined strainer.

I then placed the wrapped curd into the press and clamped it down without going crazy on the pressure.

After 10 minutes I changed the cloth, flipped it over and clamped it down again for around 15 minutes.

Not a lot of whey came out this time. I covered it in yet another cotton cloth, flipped it over again, and clamped it down hard this time.

I left it overnight, and on opening it looks a lot like it did last night. But that's kind of ok, because last night it looked like a cheese.

It looks like a cheese but smells faintly of babies. Nice smelling, healthy, happy babies, but babies just the same.

I'm not sure that a cheese should smell like a baby.

Maybe babies smell like cheese.

My cheese smells like babies.

Cheese - Reasonable cheese

I decided to try to make a cheese that works this time. This way I can discover If there are indeed any benefits from a slightly more reasonable approach to cheese making.

Keeping to my convention of giving cheeses grand names even before they turn out to be worth a name, and keeping with my new effort toward making a cheese that has a reasonable chance of becoming food, I have decided to call this attempt Reasonable Cheese.

I started as usual by sterilizing a few things, Including the plate to rest them on.

I then added four litres of pasteurized but non-homogenized milk to my saucepan. I added a random amount of starter culture, I'm guessing 1.5 grams.
And then left it sit for an hour at 32 deg C for an hour.

Four litres of milk represents an enormous confidence on my part.

After an hour I added around 2ml of rennet (I'm using a vegetarian version) and waited until the curd had set. There's a lot of waiting in this cheese making business.

Interestingly, this is the first time I have seen the green tinge to the whey that Iv'e read about. This could be a good sign.

In cheese making language, a clean break is when your whey has separated out, and your curds have set enough so that when you poke something into the curd on an angle, then lift it up, your curd should split rather than glug around. I struggled to get a picture of a clean break and failed in the end because I had tried breaks so many times there was no unbroken bit left.

The rest of this post will have to wait until tomorrow as I'm struggling to keep up with taking photos, blogging, and not destroying my cheese.

Cheese - Cheese press

After making fresh cheese, you need some kind of cheese press to to remove all the excess whey.

I got hold of some PVC storm water pipe and an end cap from stuff I bought to finish the bigger aquaponics project, a plastic lid from a coffee jar, and a clamp.

The idea was to attach the end cap and drill holes all over the place, so that when the coffee jar lid is pressed into it like a plunger, It should squish out as much or as little whey as desired. The coffee jar lid, like many things it turns out, is of a standard size and thus fits snuggly in the role of plunger.

The "120 things in 20 years whey cool cheese press" doesn't look particularly sterile, but it looks kind of cool. It should be capable of applying pressure ranging from a tiny bit, to WHEY too much.

I'll attempt some kind of sterilization on the entire apparatus. And perhaps some kind of pun removal procedure on myself.

This also means I'll be attempting to make some kind of cheese. I've been thinking that I might follow some directions this time. Or not. We shall see.


According to an independent nose, my cheese's current bouquet is

  • cheesy
  • a little sweet
  • vaguely salty
  • a little bit like vinegar 

Popular Posts