Backyard Aquaponics
A place to discuss aquaponics

Roz, yeah I think we're on the same wavelength now.

A big advantage of 'open loop' is that you are constantly diluting any irreducibles (metals, PCBs etc), albeit into your food

Yes, you would need to top up, but the claim is that the rate of topping would in fact be less than a closed loop system (less water movement means less direct evaporation). We need an automatic topperuppera in either case.

Let me write some stuff down now I'm home.

Back to John's original question...

The concepts of passive solar would say to keep the tank above ground and to insulate it from the ground. Passive solar is the idea that you orient and construct so as to absorb the most energy from the sun that you can during winter. (In the north hemisphere: south-facing, bermed in to the north, particular kinds of glass, depending on orientation of each window, etc.) This absorbed heat needs to be stored somewhere, like in heavy dark-colored masonry walls, or large dark-colored containers of water. (Dark colors will help absorb heat if the sun shines directly on them.) However, each of these thermal masses needs to be encouraged to radiate heat back into the space desired, not into the earth. Therefore, your thermal masses should be separated from and insulated from the 'outside', including the earth. So if your north bermed wall is used as a thermal mass, there should be a layer of insulation between the wall and the earth.

Now note, this helps keep air-temperature in the greenhouse more constant. The water temperature will fluctuate a bit, but that's how it works in nature, too.

Another point in the debate to bury the tanks or not. Burying them makes it harder to find that pesky leak.

My vote is unburied black poly, with insulation or airspace between the tank and the ground. Do not insulate the sides of the tank so that night-time radiation can happen.

You have a way of saying things that I seem to stumble over Janet.

My thoughts exactly LOL

Wish I knew where to get some taht cheaply. I must make some calls.

VB: foamex in bayswater. Look for a polystyrene manufacturer - I actually bought the boards for cladding our garage (world's most insulated garage .

Thanks mate - will look for a similar mob up here :-). Would love to insulate parts of my shed - particularly the part I want to have my fish tank. Could easilly enclose this area and insulate with ps.

Hi John:
The perch might like it better in the Summer to be buried and cooled by the surrounding dirt. I wouldn't bury and have outlets at the bottom of the tank at the same time. If you are sure you want to raise cold water fish that would be an important thing.

Hi Dave,
Nampa, Idaho is near Boise. Looks like Zone 5 for plant hardiness, and in the mountains. Dave, you are Zone 6, and I am on the border of Zone 6 and 7. I'm thinking winter cold is going to be the bigger problem than summer heat.

Oh, and Miwaukee has nothing to do with it. That's just on the pic that I shamelessly stole.

Here we go. John about at the west-most pink dot. Over on the east coast, Dave is the more western pink dot, and I am the easternmost pink dot.

How's that for service???

Hey John and Janet:
I think that the surface area of an 800 gallon tank won't provide enough oomph to really heat your water much, even on a sunny day. I think you should design the solar heating aspect independently of the fish tank use, rather than trying to couple them. You could get a lot of black hose and cover the back wall with it and get a lot more surface area than the tank side will be able to provide. If the fish will be OK either way I think you should insulate the tank to keep the water temps more stable, and heat for the plants rather than the fish. The other thing that may help determine if you want to bury the tank would be if you want gravity return to the fish tank - the grow beds or sump or whatever leads into the tank will have to be higher than the tank... HTH

Also, I am intrigued by nesting plastic envelopes around just the plants - like imagine a PVC cage covered in plastic sheeting around the plants. The idea would be to insulate from the cold greenhouse walls, and to reduce the air space you need to keep warm. You would then have to heat this envlope around the plants rather than the entire building. The temperatures could go like 20 degrees outside, 40 degrees in the greenhouse, 60 degrees in the plant envelope... I guess air exchange would have to handled in some way though (small exhaust fan that run in the daytime?).

I forgot about the third pillar - the bacteria. I guess the gravel needs to be kept in a good range too. There is a PDF on the web somewhere where a dude put "heat tape" in the gravel to keep the beds warm. If you don't mind using electricity for that it could be helpful too.

John, you need both thermal mass to store heat, and good surface area to collect the heat in the first place. And you need to be able to radiate back out to the greenhouse at night via non-insulated surfaces, yet protect from heat-loss to the outside using insulated surfaces. Confused yet? Here's a light-weight article on passive solar in Wisconsin, with some good diagrams and intro to concepts.

http://www.focusonenergy.com/data/commo ... sin%20.pdf

Dave, the idea of utilizing the back wall and black hose is outstanding, and would be a great way just to heat water to circulate through the tank. If we combine the surface area of the black hose with the mass of the tank, we've got something. During summer, John can cover the hose or re-route around it to keep from boiling the fish.

John, you'll notice that threads started here take on a life of their own. Tell us your thoughts on our ramblings, and we might even re-direct the way you want us to go

Several of the forum peeps here have tried using black PE? hose for solar heating, but they're all in cooling mode now...

Oh, another thought on the fish tank...right now I'm seeing the need to be able to divide up the fishies. One tank for breeding, more than one tank for staggering harvests or different types of fish...you get the idea. If you are concerned about the cost of one large poly tank, have you considered using several smaller Rubbermaid stock tanks? The largest they make is 300gal, and 2 or 3 of those would cover the capacity you are considering. You could also implement in phases that way, although you might end up with multiple (but smaller) pumps etc. More things for you to ponder. Isn't this place dangerous???

Multiple tanks have advantages, but they also have caveats. I am planning on running multiple tanks, but not necessarily the same size.
The options are:
A) to run multiple, independent systems,
B) to run independent, yet interconnected systems, (same as independent systems, but allowing different systems to level water between them), or C) to run serially connected tanks - pump from one tank, return into another tank, flow through all intermediary tanks.
Each of these has its advantages and disadvantages:
A gives you isolation between tanks keeping disease isolated to a single unit, but you could have dramatic differences between the systems in amonium, nitrites and nitrates. Also as fish and plants are harvested, you will have balance issues - fish grow, so you plant more plants, fish are harvested, so your plants start suffering from lack of poo, etc.
B would reduce the isolation, but if one tank gets sick, it can be isolated without affecting the whole system. Some fluctuations in stocking levels would be smoothed slightly, but dramatic changes in stocking or planting levels would require some sort of water interchange.
C would give you the inertia of a large system, but you would have to take steps to ensure a good balance of DO, etc.

I am planning on going with option C, but may have an auxilliary pump to mix the water from the different tanks, thus keeping DO and nutrient levels more constant througout the system.