Backyard Aquaponics
A place to discuss aquaponics

Finished off the small AP system, ready for the yabbie transfer... and had lunch....

Phone rang.... yippie.... afternoons work.....

Got back home about 16:00... thought I'd check out the tank temp as it had been a pretty warm day here today.... about 28 degrees around 15:00

Knew as soon as I went out the door.... that something wasn't right....

Tank temp (as I glanced) 28 degrees...... HSM... .....

Pump supply line to the array had parted at one of the couplings...

Yeah... one of the ones I had made a note to check... but hadn't ... as I'd decided to "tee" off to the trickle towers...

Result ... the solar array was thermo-siphoning... not pumping under the direction of the controller..... why????

Because the array tank was at 83 degrees..... ahhhhhhhhhhhhhhh....

An interesting piece of artisitic sculpture.....








.... luckily, the pump was happily pumping the fish tank water around within the tank...

And the array was slowly thermo-siphoning the water out of the array tubes and header tank......

Tank was steady at 28... yabbies were fine.....

Solar array turned off.... for modification.....

Why does "Murphy" only strike when you're away for a few hours.....

I have been having 25 degree plus days in Kal, and my water is still at 14 deg c lol, burying the tanks may be a double edged sword

So your array was actually managing to run as a thermo siphon? Hum, I had thought the water tank for a thermo siphon system needed to be above the array but I would love to be wrong on this. I don't really want to spend more money pumping water up to the roof for the main system heater array.

it was probably only running (inefficiently) because the water in the return pipe was cooling down or becaus the quantity of heated water was sufficien to push the water down in the return pipe

my two cents

frank

yea, perhaps but the heater tank got really hot anyway!

Basically yes.... the header tank (above the array) was full, as were the tubes...

The tubes were heating as they do... heating the header tank.... circulating through the tubes... heating the water... etc...

Until the water expelled (slowly) down the return pipe....

Maybe the term "thermo-siphoning".. isn't completely correct... .... don't really care....

Bottom line the PVC piping got so hot from the water running out of the unit that they softened...

The controller has an over-ride/shutdown at 95 degrees.... which would have disabled the whole controller evetually...

Funnily enough, the idea of replacing the PVC piping was discussed at my last meeting with the supplier....

Both for this scenario (thought unlikely) and more particualrly as a view to replacing them with more thermally efficient tubing to minimise heat loss, as opposed to "lagging" the pipes...

dont think you'll find a pipe that will compare to just lagging it

in the above situation laging wont do any good the pipe will just get a bit hotter [remember its heating from the inside]

Yep, their needs to be a small redesing so the above cannot happen

i was skimming again

Well we're definitely into the early spring phase.... overnight temps (air) are swinging from about 5 - 14 degrees.... and by 09:00 can be anything from 12 - 25 (:shock:) degrees.

Fish tank temps have been varying from over night lows of 18 to late afternoon highs of 25 - 30 degrees...

Presents a couple of problems...

The daily swings in tank temp.... which can be (although I haven't as yet) controlled by incorporating an aquarium heater into the solar array controller....which activates the heater overnight...

And what to do during the warmer weather to prevent the array raising the fish tank temps above 30 degrees....

Either means, reducing the effectiveness of the array heating....by setting the controller differential higher (so that it only pumps 1-3 times a day).... turning off the solar array altogether for certain periods.... or ...

Obviously... shading the tubes should be the solution.... and that's about worked out fine so far....



Crude but effective.... I leave the shadecloth off through the morning (all day on the cooler days) and just drape it over the tubes through the afternoon....

By midday on a warm day, the fish tank is usually around 28 degrees... and the shadecloth limits the heat gain enough in the array, so that it only pumps a 2-3 more times during the afternoon....

Keeping the tank pretty well constant at 28 degrees....

The other option would be to increase the flow rate... but the overflow valve limits the abiltity to do this, as the system just can't cope with more than a certain flow thorugh it...

I was playing with the idea of getting an external window roller shutter to mount over my solar heater so that I can wind it up or down as required. Unfortunatly I had 2 of them but gave them away before someone gave me my solar hot water panel.

With the fish tank at temps around 28 degrees.... and no oxygenation, other than the water return when the array pumps...

I was pondering whether I'd be starting to stress the yabbies in the tank....

Also there's no actual bio-filtration attached to the system... with only a dozen yabbies in the 1500ltr tank, it hasn't really needed it....

As I intend to move the yabbies out to another tank... and stock the tank with some Silver Perch (at least temporarily until the mega system is together)....

Figured I'd better get some oxygenation and filtration happening before the fish actually arrive....

So cut into the line from the pump to the solar array supply.... and set up a trickle filter...







As the pump only runs when the array kicks in... so does the supply to the trickle filter...

Although I will admit to not having actually thought that through completely... no matter it does have some postive advantages...

The pump doesn't operate through the night.... meaning there's no noise concern for the neighbours... and no heat loss via the "trickle" tower...

Secondly... as there's some "cooling" from the trickle tower.... as the array pumps....

It prolongs the time taken to reach the low point differential, stopping the pump... effectively "limiting" the number of times the array pumps....

End result... for the moment (anyway) I can remove the shade cover through the day...

By sheer genius (OK luck ) the angle of the sun has shifted such that the array is now shaded from about 15:30 anyway.... what a difference a month makes...

Again this should mitigate things through the summer months....

For now ... the tank is quietly a balmy 28 degrees throughout most of the day....

I'll tidy up the shade cloth idea by eventually incorporating a pull down/wind down window blind....

And when the fish go into the tank... I'll run some supplentary aeration via airstones anyway....

Great minds think alike KEII.... yeah, should work a treat....

Saves decommishing the array over summer... and protects the tubes etc...