Backyard Aquaponics
A place to discuss aquaponics

Well it's time I worked out some heating for my warm water system. The main tank is down to dangerous levels for the murray cod.

The main idea is to use my biochar system or a propane burner to provide the energy, then to store the energy in water tanks for slow release into the AP tanks overnight or maybe even on cold days.

The storage is 50L stainless tank used to boil the water, a 200L blue barrel at maximum 40c. A small pump circulates water into the boiler from the BB till BB reaches 40c. A small pump also pumps AP water into the BB which overflows back into the ap system, when the BB drops a few degrees the pump starts circulation into the SS boiler which overflows back into the BB.

My AP setup contains about 1600L of water and on cold nights seems to loose between 1 or 2c overnight.

My initial calculations indicate that I am losing about 14kJ of energy at 2c loss or about 20kJ if I allow for 3c loss.

If I set the AP temp at 15c I believe the blue barrel can give up about 18kJ while the SS can give up about 15kJ. So it would appear that if I heat the setup to capacity is should sustain the AP system fairly comfortably.

Does this make sense? Am I missing anything?

Use solar with propane instant gas boost or Solar Volt with heat pump (COP 3 or 4).

I would try solar hot water, its really easy to make one..

Care to share???

Hi everyone,

there are plenty of plans for homemade solar hot water heaters free on net.
My favorite is the matt black tank in the old fridge with duel layer glass and the lid left on the fridge to close on frosty nights.

Cheap and made from recycled parts.

There is also the option of the wvo heater instead of gas and in most cases the fuel is free.

God bless, froggo.

Trees and available space make solar not likely to be very effective here. I am hoping to provide a reasonable portion of the energy as waste heat from my biochar production. Propane is for when I don't have the time to do the biochar.

I am however open to the results from Rupert's work with solar, how is it progressing Rupert?

Besides this is how I convince the wife that the propane burner is not just for my homebrew

Rupe has been trying to do this for a few years now

making one that works decently would appear to be a problem.

The problem with a solar heater... isn't getting the heat into the tank during the day... but keeping it in during the night....

Using a release system via a propane heater as Novaris suggests... in combo with a solar heater... might be the optimal solution...

My solar array had the integrated option to control such a heater, or electric boost... just never got around to (lack of funds) actually testing it.... and again, the question arose as to the amount of power, if electric boost.... that might be used to heat through the night...

Interestingly Novaris... I planned a similar stainless tank approach... but using phase change properties of waxes, heated by the solar array during the day... and released through the night... with the possible use of a gas or electric boost...

Still something that kicks around in the back of my mind... but at the time I didn't persue things further as the manufacturer backing the project withdrew... due mainly to the problem of shipping evac tube systems without enormous shipment damages...

Hi Outbackozzie,

I've been following Rupes thread and he has done great work with his Solar AP setup.

A solar unit made from scrap or the newest wizz bang solar H/W system can heat water. The problem seems to be making it work for our purpose.

In my hothouse system I was looking at some form of heating through winter. Solar H/W, WVO water heater/furnace and Biogas were my main areas of interest.

All options seem to have their own problems but I suppose this is part of the reason we enjoy mucking about with AP.

God bless, froggo.

Hi everyone,

Sorry Rupe posting at the same time I did not see yours.

I was thinking the wvo or biogas burners/furnace could heat the water at night through a heat exchanger and radiant heat.
Both of these are do it yourself low cost options but require frequent attention.

God bless, froggo.

In most cases you have 3 to 4000 litres of fish tank water and in a storage system you have 100 litres
100 litres isent gunna heat 4000 litres
You would probley get more heat gain piddling in the tank

Well yes and no Froggo.... solar H/W systems heat water to 60+ degrees... for hot water.... and do so with the use of copper heat exchangers...

We can't use that style of heater directly... by passing the tank water directly through the unit....

So that means exchanging the heat generated by a seperate closed loop back into the fish tank somehow... and again with copper excluded, this poses problems of efficiency of heat transfer....

And still leaves the problem of heat loss during the night...

Even with my purpose built array... I can comfortably gain anything from 2-6 degrees of heat during the day.... but will loss it all, or more, through the night...

At best I can maintain, or slow the cooling of the tank... and a higher "average" temperature through winter...

Agreed, having a system in a greenhouse would provide greater control... especially if a double "bubble" film was utilised... but even then ... a lot of latent heat is lost from a normal greenhouse through the night...

To date... the most effective way of maintaining tank temps.... is to not pump through the growbeds at night...

Heres a bit of info to digest i have an eden 8 by12 ft glasshouse theres a gas heater proper eden type running all the time
Inside theres a 1000 litre fish tank and 5 100 litre grow beds
Yesterday the glasshouse temp reached 38 deg
Water temp got to 18 deg
Overnight outside temp fell to 5 deg [still is ]
This morning glasshouse temp 11 deg water temp 14 deg
Tonight i will test by not pumping over night

I think Creative1 might be on to something with the constant flood during winter to help maintain water temps. Or actually any time you want to maintain water temps from being as affected by the extremes. Flood and drain may work far better for oxygen exchange to the plants and bio-filter, but flood and drain is also very efficient at chilling water on cold winter nights or heating water on hot summer afternoons.

Even so, some additional heat would be required to keep warm water fish happy/eating/growing in a temperate climate winter.

I found that solar heating wasn't really enough without having a really huge hot water storage tank. 100 gallons of hot water storage definitely didn't cut it with my big system and flood and drain grow beds.

Hi TCLynx,
I dont know much about it all, how about Wind generator,
Here there is just about wind blowing all the time.
Regards Eagle

Agreed on shutting the pumps off at night! Definitely conserves temp gains from the daytime.

On thing that has proved a good warmer for my water is the NFT rack over the sump. The water depth through 8 or 9 4" pvc tubes is about 3/4" and it cascades from each tube back into the sump. Not sure what the measurable gain is, but the water temps dropped dramatically when I accidentally left it on one night, while I see strong gains during the day with it running.

Koi ponds sometimes use a similar system to aerate and cool, so I do not see why it wouldn't provide nice gains in the day.

Currently, I have the small nft pump on a timer that runs from 8 a.m. to 8 p.m.... Wouldn't be too difficult to run it on a Steca thermosensor such that anytime the air temp was above the water temp it came on... I know here the second day I had the cover on the GH it snowed. Early the next day it was 38º F outside and 83º F inside. I had NO heat gain from water or the 20 tons of gravel in the floor (both of which I expect to lean on as thermal mass next Winter), but a set up with a thermosensor and cascading water may be a good way to pull heat into the sump...

Another trick the old hands on here are sure to know is to run your water level a little higher to suck the heat off the upper most rocks that are exposed to the sun...

My thoughts.

Hoping to learn more here as I think ahead to this first full Winter in the GH...

CB