Insulating the growbeds

Today is Anzac day and that is traditionally the start of winter in this area.
I have been concerned for some time about how the fish will fare during the winter as it gets quite cold here in downtown Burra Creek. (Actually there is no town of Burra Creek- it is almost all ex farming land - never great farming land and now mostly hobby farms).
Already the nighttime temps are dropping below freezing outside and we have had cold enough weather to kill off the tomato plants which were growing in the dirt garden.

I had always intended to insulate the grow beds as they are above ground in the big shed and as the air temperature there is now dropping to as low as 6 or 7 degrees Celcius it is clear that the water temperatures will eventually drop as well. Current water minimums are in the 13 to 14 degree range so the tank insulation is clearly doing what it is supposed to do.

I had intended to wrap the growbeds with a product called Aircell which is a lot like heavy duty bubble wrap with a layer of heavy aluminium backed sisalation like material bonded to the bubbles. However I was quoted over $300 for a single roll which is 10 metres long by 1300mm wide. It would have been enough to wrap all the growbeds but I decided that was too much money. Instead I bought a similar sized roll of sisalation backed fibreglass batting for about $120. This was split into 3 rolls about 400mm wide and then wrapped around each growbed.
The reflective layer is fairly fragile so I then wrapped the beds with the Sisalation I took off the roof when the steel was replaced with polycarbonate.
This also had the benefit of covering over the fibreglass. This should protect the fibreglass from damage and also protect me from the batts which can cause a lot of itching.
We folded the extra Sisalation over the top lip of the growbeds . It is held to the top by a length of split 13mm poly pipe which should keep it all neat. Attaching the poly pipe was not a fun job but if it keeps the whole lot together it will have been worth the effort.

It will be very interesting to see if this part of my plan works as there will still be some heat loss from the tops of the growbeds. The next phase of the construction is the creating of a heating system for the water.

These 2 pictures were taken today. Sharp eyed viewers will notice the beans have gone from the closest growbed during the construction. Peas are the next crop to go in under the wire supports.
We have also pruned a fair bit of the tomato leaves from the plants which are still going well and with a bit of luck they will continue to produce fruit for some time yet.

Plant growth update

10ft tall tomatoes!!
Well perhaps not quite 10ft but they are much taller than I am even when I am standing on the gravel in the growbeds. In fact some seem to be trying to escape out the window at the top ridge of the shed.
The first picture shows the tomatoes about 6 weeks ago and the second , more recent picture, shows much bushier growth with runners almost to the roof! We have eaten a fair few of the fruit but there are now a bit hard to find in amongst the foliage. I plan to do a fair bit of leaf pruning fairly soon. Early fears that the flowers would not be pollinated don't seem to have come to pass and although not as prolific as I had hoped we are still getting new fruit. With a bit of luck we will continue to get tomatoes from the aquaponics setup for some time yet. In the dirt garden I expect that we are at the end of the season as the frosts are likely very soon.

Despite my earlier comments about lack of nutrients and light the vegetables have been quite productive.
We have had 2 separate batches of tat soi, several of lettuce, and good supplies of peas.
The coriander , in the picture with the beans, was a bit of a flop as it went to seed very quickly- Di reckons it was too hot at the time. Some of the other plantings also went to seed a bit quickly -perhaps for the same reasons. We also had rather slow growth with one of the lettuce varieties and the leaves were bitter so they were pulled out and fed to the chooks
We are currently getting a feed of beans about 2 or 3 times a week from about 30 plants- 10 in each grow bed- some are low as in the picture while the rest are growing on the supports I put in for the peas and tomatoes.
I have not really been a gardener before and so it is quite a thrill to be able to harvest fresh produce whenever I am in the shed.
All I need now is for the fish to produce MORE POO!
This is probably unrealistic now and I will have to wait for the warmer weather to return.

There is however the plan for a hotwater heat exchange unit for the fish- more later!!

An imagined problem and a solution?

Fish need oxygen to breath just as we do and they get it out of the water. The constant pumping of the water out of the tank and through the growbeds and back into the fish tank provides a lot of air to water contact which ensures the continuous exchange of gases.
It suddenly occurred to me a few weeks ago that if I had a pump failure for whatever reason, and I didn't know about it for some time, I only go over to feed the fish once a day, I could possibly end up with dead fish due to low dissolved oxygen in the water.
This is not really likely to be a problem at the moment due to the small size of the fish but when they are bigger it could be a very real problem. I imagine 200 plate sized fish need a fair bit of water/air contact to prevent them suffocating!
So I went looking for a big air pump- just like the ones used in aquarium setups but bigger.
It had to be at least capable of running on 12 volts and even better 12Volts and 240Volts.
I found one on eBay, bid and won, and a few days later it arrived.
I would not want to have it in a home aquarium setup because it is very large and quite noisy compared to normal aquarium pumps.
However it pumps about 40litres of air a minute and the box contains a 12Volt 7Ah sealed lead acid battery and charging circuitry etc which means that if the power fails it continues to run for some hours on battery power alone. I could also hook up a 12Volt input so that even if my inverter fails I can still keep the fish alive.
At least that is the theory!

Problems and solutions?

Although growth of the plants in the growbeds is quite vigorous they don't seem to be doing as well as I had expected.
I am reasonably convinced that I have 2 main problems:-
1. not enough light and
2. not enough nutrients.

So in an effort to solve or at lease improve on the light problem I decided to install the extra polycarbonate roofing I had bought at the beginning of the construction.
Taking advantage of a visit from my "nephew" I co-opted Gary into being a roofer's mate and we removed the zincalume roofing over the back part of the shed over the fishtank. This is a reasonably straightforward job despite the difficulty of trying to drive "one-shot" tek screws into polycarbonate sheeting whilst not putting any weight on the sheeting. Fortunately the sheeting is very strong and the occasional accidental step on it doesn't result in a crash through to the ground 4 or 5 meters below.

The fish don't seem to realise that the extra light is good for the whole system and they are currently much more skittish than they were before the extra light became available. I am hoping that they are just getting used to it and will eventually be more willing to be seen.

The not enough nutrients problem is almost certainly due to the fact that I have quite a lot of plants and not enough fish poo! There are probably over 200 fish but the biggest of them are still only about 100mm long- and a lot are much smaller.
So as mentioned in an earlier post I am adding pure Urea at the rate of 4g most days- this has lifted the nitrates to between 10 and 20ppm without causing any detectable ammonia or nitrites.
I was also adding chelated iron at the rate of about 5g per day for a couple of weeks. I was testing for iron in the water but not getting any detectable levels. However I should have been testing for the chelated iron and when I finally did so the levels were between 1 and 2 ppm. This is possibly too high a level so I am no longer adding iron. A test today suggests that the levels are a bit lower and I hope that the plants will take up more. As far as I can tell chelated iron is not toxic to fish and the fish don't seem in any way affected.

The fish are also eating less now due to cooler temperatures.
Temperatures in the shed are now a fair bit lower than they were in the middle of summer- not a surprise- as I write this the temperature outside is only 10 degrees Celcius. The tank was at about 15 degrees earlier today. The insulation I have around the tank is clearly helping to moderate temperature swings.

Unexpected Visitor

On arriving in the big shed a few days ago I was surprised to see that one of the "fish" was swimming around the perimeter at the surface really quickly.
And then I noticed that there were flashes of red from this "fish".
A closer look quickly showed that it was not a fish but a smallish red bellied black snake! I estimate this one to be about 800mm long.
Clearly it had visited the tank in search of food- The primary food for red bellied black snakes is frogs and other small reptiles.
The big shed is within 20 meters of the big dam and I have often watched red bellies hunting for prey around the edges of the water.
My first thought on seeing the snake was to quickly rescue it as I reckoned it was probably exhausted after who knows how long in the water. I have a small aquarium net taped to the end of a short piece of pipe so this was presented to the snake who immediately swam into it. I took the snake out to the bank of the dam and put it on the ground near the water .

I then realised :-
1. That I had missed a great photo opportunity and
2. That the snake might have eaten some of my fish!

I went back out to see if the snake was still where I had left it and it was- soaking up some warming sunshine. It didn't look like it had a fat belly so I doubt if any fish had been caught. It did look healthy and eventually moved off into longer grass to hide from me.

The fish were a bit skittish for a few days but eventually returned to normal and I although I have no way of counting them it looks as if I still have as many as I had before the visit.
I must come clean and admit that these pictures are not of the snake in this post- I prepared these images earlier. It is one of the snakes which live near the dam which I had photographed some years before.