Safe/Economical/Powerful pond pump solution?

[mcpond]

Hi,

I'm from Australia and currently building a pond of approx 250ltrs. The pond is at the base of a rock retaining wall (approx 1.5metres tall).
I'm pumping the water from the base of the pond, to a filter i've made at the top of the retaining wall, and then out and flowing over the retaining wall to make a waterfall.

Currently i have a cheap AC submersible pump (2500l/h) thats rated to a head of 2.3m, it works fine however the power cord isn't quite long enough to reach the outside power point, i have to use an extension lead, and eventually i want to run it all in conduit and put some pebbles over the top, which would require me to extend the power of an already potentially unsafe concept (submersed 240v).

From what I've researched, my two main options are:

1) a 240V AC pond pump that has a long enough power cord (around 5 metres).
2) a 12v bilge pump & transformer to connect to the power point.

Solution 1 is the most straight forward, but the most unsafest due to 240V, i'm guessing i'd need some kind of circuit breaker aswell.

Solution 2 is safe(12v), easier to run wires, but my concern is are bilge pumps reliable to be run 24/7 and they seem less economical.

Any help of finding a pond pump solution that is safe, a head of atleast 1.5metres and be quite cheap to run (< 50watts) i'd love to hear about!

 

[sissy]

Welcome and I know over there they use oase aquamax pumps a lot .The sights for pumps usually tell you head height and that is the part of the hose that comes out of the pond and how high up it goes

 

[Big Lou]

Welcome McPond.

 

[mcpond]

Thanks for the info, i just had a look but they're well out of my price range unfortunately ($250 AUD+).

I looked further into the 12v/24v DC powered pumps, but they're quite expensive and not as efficient as mains powered pumps (although alot safer).

I'm now leaning more towards the less safe, but cheaper and more efficient mains powered submersible pumps (240V AC) e.g. this pump on ebay:
http://www.ebay.com.au/itm/Jebao-TM...ter-Pump-30W-Only-Energy-Saving-/191114751480 .

Its $88 (which is basically my budget), rated at 3500 l/h, consumes 30W of electricity, has more then enough head and has a 10 metre electrical cable. It ticks all the technical boxes for my pond/waterfall situation, leaving safety as now my primary concern.

Because this is a mains powered pump that is submersed, i want it to be also safe. I don't know alot about electrical safety (except for water + electricity + person isn't a good combination), from my limited reading i see that to ensure safety for mains powered submersible pumps incase anything goes astr, you need a ground leakage device/circuit breaker/RCD?
Is this correct? and if so, would something like this:

http://www.bunnings.com.au/excalibur-outdoor-rcd-safety-adaptor_p4420376

be sufficient to plug the pump into, and then plug into an outside power point?

Sorry for the million and 1 questions, i just want to make the correct purchase decision whilst ensuring safety, i just don't like the idea of mains powered electrical devices submerged in water , i know its not a new concept and millions of people probably do this, but would just like that extra bit of protection/peace of mind.

 

[Meyer Jordan]

You are on the right track...safety-wise. What you call a 'RCD safety adaptor' is called a GFCI (Ground Fault Circuit Interrupter) here in the U.S.. Interesting that Australia would only have 240V power supply. 120V and 230V available here. The vast majority of pond pumps here in the U.S.are 120V.
I don't think that the pump that you have chosen will be powerful enough to suit your needs plus it only carries a one year warranty.

 

[mcpond]

Thanks for the info Meyer!

Currently the cheapo ($25) 2500 l/h 240v pump i'm using has been able to provide enough head and flow to accomplish the task. Therefore i think the 3500 l/h should be an improvement on my current situation and provide a little bit more flow for the spill over for the waterfall at the top(though the difference may be negligible).

If i can find a cheap 4500 l/h pump with a long electrical cable i'll opt for that, as i think that would be the most ideal as far as flow rate/energy consumption goes. The next one up seems to be around 6500 l/h which i think will be overkill and uses 50-60w, basically double the energy consumption.

Thanks for your help so far everyone!

EDIT: I did find a 5000l/h model, consumes 40w (http://www.ebay.com.au/itm/New-Jeba...265759?pt=AU_Pet_Supplies&hash=item5ae8420f86)

At a head height of 1.5m with a 5000 l/h pump, i'd be getting a flow rate of approx 3500l/h (925 US Gallons) according to the charts i've looked at. Is that flow rate an overkill for a 300 litre pond (80 US Gallons) ?
And if the flow rate is too much, could i add a ball valve at the top of the waterfall to slow it down/control the flow without any ill effects?

 

[mcpond]

Okay after alot of googling all day and seeing whats available over here, I've found what seems to be a pretty good middle ground. I've finally found a DC pump that on paper, is the same as the AC pumps

Specs:

24v DC
Flow rate: 6000l/h
Head: 3.5metres
Power Consumption: 40 Watts

It has a controller in which you can adjust the flow rate and scale it back upto 60%, i

Link: http://www.petsandponds.com/en/featured-items/p17713231.html

It is alot more then i had originally planned on spending (approx $170 AUD), and about $70 more than the 240V AC version, but its 24Volts (alot safer) and still efficient and economical, so i'm willing to pay the price. Only downside is it has a 1 year warranty.
What do you guys think?

 

[Paultergeist]

Well, the vast majority of American ponders are using 120V (AC) mains power for their pond pumps (as well as other accessories such as UV, air pumps, lights, etc). Used correctly, there really have not been a lot of safety issues associated with AC-powered pumps.

The value of the DC-powered low voltage pumps -- to me -- becomes more apparent when I look at solar-powered ideas or running a small pump off of a car battery, etc, but I do wonder if your focus on trying to go low-voltage/DC is really limiting your pump choices?