Backyard Aquaponics
A place to discuss aquaponics

Plastic high temp tube running inside the glass.

Nope.. they're a sealed toughened double glass vacumn tube... the outside surface of the inner glass has a darkened coating.... think thermos flask....

Water circulates through tubes>header>tubes... until pumped from header>tank>header...

Hard to break as such... unless the ends are suspended and you jump on the middle of them, or drop something heavy on top of them...or stick forklift blades through them ... like when they're being transported... grrr...

So yes OBO... the fish water is pumped through them and circulates through the header tank... hence the requirement that no copper components were incorporated into the design...

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Data from installed systems using these tubes shows that they very rarely break through both glass linings...

If the outer glass is cracked and the vacumn broken ...the lower end goes white... a visual indication of a problem...

But as long as the inner glass is unbroken the system will continue to function as per normal... just one tube less efficiently...

Obviously... the system needs to be taken offline and drained when the tube is ultimately replaced....

And yep John.... doubled checked.... will withstand hail to 25mm....

I stand corrected, looked like plastic pipe inside

Different to the ones I saw. They are gas filled glass tubes that superheat copper prongs that go into the holding tank. Not sure what the gas was, maybe refrigerant. You could not hold the prong if it was out in the sun fo a while.

Well without the heat pipe, it is one less thing to fail and I suspect that with the controller set up if a tube does break (very small chance once set up and running), the odds of loosing all the water are slim.
Good work Rup!
Looking forward to your heat gains once you set up a reflective back.

There is a firm locally that produces heatpipe type evacuated tube panels.
It seems there are two types, one has a double wall tube with a vacuum and the heatpipe is inserted into the tube and capped. Effectively, the heatpipe is in "still" air with a vacuum "jacket" for insulation.
The other type is more expensive, it uses a single wall pyrex tube (70mm dia) with a sealed vacuum, the heatpipe is factory fitted and sealed inside the tube.
Apparently these have a much faster response than the double wall version.

A 1.8m long x 70mm dia single tube (sealed type) costs £35, i might have to buy one to play around with

Think all the heat pipe systems utilise a copper pipe, with copper end caps... into a copper heat exchanger inside a header tank.... great for hot water heating...

Not for fish... or fish nutrient water, which would rapidly react with the copper in a recirculating environment...

Hi Rupe
I think your solution is the easiest, safest for fish and the most cost effective.
The only way i can see to utilise the copper based tubes is to run it as a solar powered storage heater of some sort.
A closed loop (via thermosyphon perhaps with no upper temp limit) running through a very well insulated sandbox or similar.
A second non toxic pipe loop in the sandbox connected to a pump controlled by a make-on-fall stat heating the tank water as required. You`d probably need a pretty huge sandbox though

top work Rupe ..... add a electrical heater to smooth temp diffs , and to provide heat at night ..... PROBLEM of tropical fish in sub-tropical climates basically solved.

Tank better insulated , grow beds in green house and SMILES for barra or Jades in winter.

Unless you can get the copper replaced with stainless. Or the copper end coated in something(might not work because you would not be able to see if it had a leak). That's why I was thinking the header tank was sectioned into two. Oil in one part and water in the other. Heat the oil and have the heat transfer to the water.

Looks fantastic! And quite a reasonable price. Canberra summers are hot - is there a way we can utilise it so we can cool the water on those 40 degree days in summer? I gather we can't because they are vaccume tubes and hence won't carry any heat out.... could you "plug 'n play" a different type of tube to cool during summer?

Good question GEM...

I think I'd prefer to see a more efficient copper based system that can be plumbed into my home electric hot water system. With a modified controller and some fancy plumbing the hot water can be directed to the tank when needed through some kind of heat exchange and when not needed,....8 months a year around here...the hot water is directed into the existing home hot water system.

I've seen units advertised that integrate into an existing hot water system, what I'm thinking of is something like that but the hot water is directed to the FT when needed there more than the hot water system. Would get better return on your investment and the power you save from solar hot water heating would offset any pump powering expense. Perhaps what you could look at is a customised controller and a stainless steel heat exchange loop to be plumbed into a more standard setup.

Of course, this only works if your system is near your house.

You could do Monkey... but the temperature of the water output from such a system is usually set to above 60 degrees... both by standards and by the controller...



Temperatures this high would have detremental effects on fish ... if the water were to be piped directly to the fish tank... indeed the temperature shock would probably kill the fish...

You could use thermostatic mixing valves or tempering valves... to limit the temperature of the water temperature....

Given that such evav tube systems utilise copper heat pipes in the tube, end caps and a copper exchanger... and copper within the actually hot water system tank.... and considering the affect of copper on fish/crustaceans...

You'd need some sort of intermedairy holding tank...with stainless steel heat exchanger... to exchange heat to the fish tank water in a seperate loop...

You'd also need another pump and additional plumbing.....to deliver water from the hot water system to the stainless heat exchanger...

You'd need another controller, or another function on the solar controller to ensure that the water entering the fish tank wasn't too hot... and to set an upper limit of fish tank temperature... so you'd need another couple of sensor probes as well

And such systems are usually roof mounted, an installation usually done by licenced plumbers...

While similar heat tube systems sell for about the same price...the additional costs, including power...may price such a system either out of reach for people or above that of just running aquarium style tank heaters...

Luckily the controllers in the kit do allow for an electric boost circuit... which has a seperate settable temperature range and with the addition of a holding tank could be incorporated...

It's an area/modification that I'm currently working on.... incorporated into the kit as it exists...

Idea being that either...

We heat water in an incorporated holding tank by an electric element and exchange heat through a stainless heat exchanger and seperately pumped loop to the fish tank.... or pickup a loop from the house system...

I'm opting for the former rather than another loop from the house system for reasons of plumbing cost, and practicallity....

Something like this.... which just happens to fit nicely under the solar array....


Ive also been discussing the use of "phase change" materials such as parrafin wax banks.. which could also be incorporated into the above tank....

But these are all modifications/refinements for the MarkII version...... and untested as yet...

Cost is the significant disadvantage of the system you describe.... and maybe a limiting factor in any proposed modifications....

I'm working on it