Backyard Aquaponics
A place to discuss aquaponics

The site says:
With this 24V low voltage pump you can extend the low voltage cable with connectors to a total of 60m before a voltage drop occurs
Unfortunatley the cabling they speak of is $2.90 a meter, which would end up costing me a fair chunk of money (almost as much as my greenhouse).

24W 24V low voltage would mean 1amp draw right? I'm starting to think it might be cheaper to get solar panel and battery than get a sparky out to wire things up...

24W 24V 1A correct.

yeh the cable is expensive because it is much thicker copper to carry the higher amperage.

if you went solar then you'd need to at least double (probably more) your solar panel watts to pump watts. Others have more experience..............

Hold the phone gem!

if you're only drawing 1 amp then just use a chopped up bunnings 25M extension lead. i'm fairly sure they're rated at 10A. hang on, i'll do the calcs.....................

ok, at a 25m run then 1mm2 cable should do nicely. the extension lead i'm talking about will be this.

THATs what you meant! I thought you meant buy a bunnings cord and run 240V out using it. I see now, just do a little rewiring of the extension cord and thats my 12/24V extension.

How did you work out the length/cross section/max amp (whatever you worked out)? Just a formula will do because I may want to use 2 pumps in the end and I don't want to use you as a calculator =)

i cheated and used a web based calc.

there is setting for 12V 24V and 48V. Technically the voltage drop will be the same for 1A at each of these voltages, but when you use the voltage drop as a PERCENTAGE of your supply it means that you need thicker cable for the lower voltage. EG a 2v loss over 48V isn't as bad as a 2V loss over 12V

anyway here is the link. Have fun

http://www.renewablestore.com.au/catalo ... =wire_calc

Don't worry about the cables it shows, just use the mm2 figure.

dollar for doallar you can't go past the chinese extension cables 1mm2 3 core flex from jaycar is $3/m

Dobber, anyway its 45m and I don't have a sandwich maker.

Awesome, I get discount with anything from jaycar.

$3 a meter is still going to cost me $75. I suppose that's about $400 cheaper than a solar cell though.

I need to get gravity working for me.

I've read VBs thread and the "center drain on syphon". I now understand what an auto siphon is (that is so cool). But I'm struggling to visualise how to use them.

I can probably use the tap at the bottom of the IBC and good ol' gravity to push water into my beds, but is there a way I can turn it on and off automatically? There has to be an electric or timed valve I can use for the IBC.... in fact...what about one of those magic garden hose timers that use the pressure to drive the timing? Or something like this puppy.

Or what about using what EB (earthbound for the uninitiated like me) describes as a dump tank above the growbeds which then uses an autosiphon to flood the beds...

Alternatively, should I have the IBC constantly pushing water onto my beds and create an auto siphon in the beds that drains quicker than the water comes in. I'd then have to get a pump which can pump from the sump quicker than the beds drain (my sump is a half barrel so not much room for error in that). I've already got a drain system set up so I'd be undoing some of that good work.

Final alternative is to invest in two decent pumps and some 2A/24V capable wire and leave the gravity feed/siphon effect coolness for another system?

thats what i was saying gem, bugger paying that for the cable, just get a cheap ass 1mm2 extension cable and chop it!

Goddamn. So to summarise, I misunderstood you. Then I understood. Then I misunderstood again. Now I'm back to understanding. The thing thats stufft me is that i don't actually know how much a 25m bunnings cable is going to cost. It could be $75 for all I know.

sorry dude, they're like $14 or $17 or something like that! i'm just going to pick up another one tomorrow and i thik they're 25M but at least 20M...............never thought i'd have to quote specs for them! LOL

I saw 30m heavy duty ones at "B" and they were about $25 I think..

red and yelow stripes? these were definatly under $20 they had two pallet loads

Awesome. Assuming 1 pump then I use the "B" cable. If I need to go two pumps, I'm stuffed (or I need better cable). So I really need to sort out this gravity feed. .... does anyone know what I can use to start/stop a flow from the IBC? That solenoid looked hopeful, but it has an "inrush current" of 0.4A which would mean I pull max 1.4A and need 1.281mm2 cable so the bunnings one probably wouldn't cut the mustard! And of course I'd need something to control the solenoid which would also pull some current.

Is the pump rated as "continuous??...

If not...Can't you on/off your pump with a timer????.....

gem, if you run a second pump just buy two cables and parralell them

i'm probably gonna stop giving electrical advice with this comment.............i wouldn't worry too much about the inrush current for the soleniod........it'll only be for a couple hundred milliseconds anyway (can i get away with saying that for LV 24V?)