Backyard Aquaponics
A place to discuss aquaponics

I'd go for milder, tenderer and moister. I've had some purchased tilapia that was too fishy flavored. Probably sat around too long.

The first time we had tilapia, it was definitely too strong. This time it wasn't bad, actually stood up well with the walleye. :-)

It's amazing how much work it takes to dismantle something. We stripped everything out of the greenhouse this weekend, including the old bed.

Dirt has great thermal mass but dosn't insulate very well. Heat will move through earth (natural ground, mud brick, clay, adobe, rammed earth, etc) roughtly at the rate of one inch per hr.

In housing terms if you have a house with one inch earth walls where there is an outside temperature of 30c then in one hr the inside surface of the wall will be 30c and shortly thereafter so will the house.

Burying tanks and GBs will help buffer them against temperature swings but if they experience prolonged temperatures outside of whatever temperature range you want then burying them is going to cuase you problems . In prolonged heat or prolonged cold the thermal mass of the ground will work against you unless the tanks, GBs or the foot print of the GH is insulated.

I think that where Healingdeva lives they have really cold winters so insulating the GBs is the go. The question of whether they should be buried hasn't much to do with temperature.

Stuart,
I was meaning with the 2 inch air gap between the earth and tank caused by the cage. (so long as it's covered at the top)
However I thought it was a better insulator than you say... very interesting. I may have to redesign a couple of things now.

So based on what you say, the coolness of mines and buried houses in CooberPedy is just because at night they are able to cool sufficiently that they do not heat up much during the day? So this only works in the desert with icy nights?

Yes, earth will draw the heat away from the greenhouse or a buried tank/bed. As Stuart mentioned, it does a great job at moderating heat but does not insulate.

Currently we have 4 inches (101 mm) of lava rock under the 2 layers of concrete blocks. Lava rock does not conduct heat away so helps to insulate from the earth. With burying the tank, we will likely use foamboard to insulate around the tank. The lava rock is sharp and I'd be afraid of it making it's way through the plastic over time... especially with pressure from dirt on the outside.

In our area, winter temps are typically in the low 30's F (0C) but we have times like last week when temps dropped to 17F/-8C. The biggest challenge is the lack of sunshine. When it's cold like that, it's sunny so we will try a solar heat collector. When it's in the 30's, its often gray and rainy. Though this morning we woke up to a beautiful covering of white snow.

I am impressed! Do you have pics of when you built the green house? I do not think you will have much of a problem with temps as you already grow through out the winter. It will all depend on your choice of fish. If you choose a tropical then they will be the deciding factor on temp control.
If a cold water fish then the veggies will be the deciding factor.
I will recommend that you keep records of all of this as you progress so that if and when you want to be organic it will be much easier.
Well done.
Think about circling the tank with a line so you can pump water thru it perhaps in a closed loop from your heat bank. Not sure but I think this would help greatly in stabilizing temps.
I have my tank in a foamboard box with a coil around the tank but have yet to hook up the coil so can't give any real data on how effective it would be.

We do have volumes of pictures of the greenhouse construction. :-) I put up a few here:

http://www.livacious.com/node/60

If there's something more you want to see, let me know. This was a fun project that we planned and built two years ago. Last year was an herb garden and a rain garden among other things and this year is aquaponics and chickens.

Nice, is your north wall plywood then? And the little addition on the north, whats in there?
Naturally black buckets or painted black?
Picking your brain, picking your brain.

The north wall is plywood that has been primed and painted with outdoor paint. It is actually an insulated wall with a storage shed on the back side. The east wall is also the same construction except with a window in it. The theory is that you don't get sunlight directly from the north and sun from the east is minimal compared to south and west. Technically in our area, we could have gone with an open east wall but chose just to use the window.

The buckets are actually a dark dirty brown color... both because it's paint we had on hand and because I am an aesthetics person...

There's a great article that I used as a the basis of the design of our greenhouse at

http://www.survivalplus.com/foods/page0009.htm

Beyond that... I can tell you the best heat sink (that's easily accessible) is water. Concrete is a good second best. I'll see if I can find the info I have on that as well.

Edit: Here's the other good link

http://attra.ncat.org/attra-pub/solar-gh.html#Solar

Ahh, was hoping it was paint on the buckets. What type? just a latex?

Paint was Bulldog Tie Coat - color Darkroom

And your footing? Just a slab of poured cement? Did you pour footings below the frost line or put something under the cement?
I plan on using Blue barrels for my heat bank in a new green house, painted of course. Water will constantly be circulating thru them in my current frame of mind.

:-) We don't really have a frost line as we seldom get below freezing for long. This last week was the exception rather than the rule. Generally, I do believe the foundation should be below the frost line. We actually made it a foot wide (the recommended width in my research) and it seems 10" deep, though it is deeper on the back because of the slope of the yard.

It would seem that water circulating through the barrels would only be beneficial if it is being heated at some point. When we're done here, we will have a combination... the water that is the AP system that is obviously circulated and the water in the buckets that are sealed and hold in heat.

I'm hoping we can build some kind of solar heat collector to run part of the AP water through during the day that turns off at night... or ideally, when the temp of the water coming out of it is cooler than the temp of the water going into it. We'll see what we come up with. Been studying the Solar heating water thread for ideas.

I would love to get my hands on a evacuated tube collector but alas the silver is running low. Maybe when the Government sends out the bribe checks it will be a go. ...chuckle..