Outdoor thermostat and pond heater

[F]

Management is concerned that the goldfish in the pond are, as last year, going to die if the pond is frozen over for anything more than a few hours, so it looks as though I need a heater, a thermostat to turn the heater on when the temperature drops to ~0ºC, and an outdoor socket.

Toolstation do a suitable socket

Seapets sell a heater , but I can't find a thermostat.

Anyone able to suggest a source for the thermostat? Comments on the socket and heater would also be welcome.

[Steve]

,

We don't have a heater in there but we do keep the waterfall running

24/7 365 days/year. Quite surreal last year to see about 2 - 3" of snow and ice over most of the pond but a hole of about 15" diameter around the waterfall :-)

[Nightjar]

,> but I can't find a thermostat.

The floating pond heaters I have bought in the past have always had a built-in thermostat.

Colin Bignell

[Dave Liquorice]

Well do you need the socket? The heater has a 10m lead, fitting an external socket carries some red tape (if you are worried about that sort of thing).

The heater is only 50W is it worth worrying about a thermostat? Even if you leave it on 24/7 for the next 6 weeks it's only going to cost about a fiver in electricty. How much is a stat going to cost and the weather proof enclosure for the connection into the heater feed etc...

[F]

Ah, the heaters I had seen had thermostats to prevent them from overheating, not to decide when to turn on and off.

[F]

I was thinking in terms of getting the power out to the outside of the house. It would also be useful for powering other 'stuff'.

Thanks! I hadn't looked at it like that.

[Roger Mills]

The socket is fine for that - I've got a couple of similar ones myself. Technically , all outside wiring is covered by the dreaded "Part P" - but you may choose to ignore that if you know what you're doing. In any event, it's important that it's connected via an RCD inside the house. Best to use armoured cable btween house and socket, too.

[Roger Mills]

We used to have something similar, but ISTR that we just had it on a timer. Ours only used about 60 watts, and just maintained a hole in the ice about 10" in diameter. Had it been cold enough for long enough, it wouldn't have prevented the pond from freezing solid.

More recently, we use an air pump - with under-water air-stones - instead. These are on over-night all year round, and provide extra oxygen for the fish. In the winter, they have the added advantage that the bubbles rising to the surface keep the water moving enough to prevent it freezing - so we have several holes in the ice, each about the same size as a heater would produce.

How deep is your pond? If it's shallow enough to freeze solid, nothing is going to save the fish. Ours is over 2' deep and our 60+ golden orfe have survived in it for many years - including last winter, which was the most severe in recent years.

[Paul D Smith]

...snip...

Surely the last thing you want is to turn over the water? The warmest water will be at the bottom of the pond (water is densest at 4degC) and surely keeping it turning over will hasten the cooling and chance of freezing.

Does a 60W heater really not manage to keep a small circle ice free? I'll admit no knowledge here as I've never used one but from my time keeping tropicals, I remember the adverts for them and the implication always seemed to be that they were good enough to do this.

Paul DS.

[charles]

I can't see Part P covering extensions. My newest outdoor socket - other ones pre-date Part P - is simply a made-up extension lead terminating in a weatherproof socket on an outside wall. It is fed from a 13A socket on the other side of the wall. It came in very useful on Saturday when I plugged in a battery charger for my car. The cold ( reduced battery capacity & thicker engine oil) meant that on Saturday morning the battery only just had enough in it to start the car - I thought it wasn't going to, for a moment.

[TMC]

Last year for the first time when it was prolonged cold I did drain these and turned on the pond heater

They are so cheap to run it does not matter if you forget to turn it off in warmer spells

It kept a decent hole in the ice

regards

[F]

It's sounding as though that's the way to go: a simple, low wattage heater.

Does that move the bottom water? That should be at 4ºC and the 'warmest in a pond that's freezing over.

The pond's 2' 6" at its deepest: I included a 'sump' to avoid it freezing solid. We had dead fish and frogs last year and a spot of reading seems to suggest that they died from being poisoned by gases trapped under the ice. They were frozen into the ice when we found them with water below, so I assume they died, floated to the top and were then encased.

[TMC]

about a metre in the deepest part so little danger of freezing solid until the world gets much colder

[Dave Liquorice]

Correct a plugin extension, ie not something permenantly hard wired isn't covered by Prat P. The wise would have it RCD protected though, either by virtue of being plugged into RCD protected ring main or by having an RCD plug. The former has the problem that do something daft outside an half the house goes off as well.

You can get kits that comprise an RCD plug, a length of flex and an external socket, these are perfectly legal to install and use.

[Roger Mills]

Well, I did wonder about that, but it's not churning the whole pond - just 3 or 4 small areas where the air stones are located. There were no problems all through last winter - which was pretty severe.

Yes, a 60w heater *does* keep a small circle ice-free, but having installed the air pump and stones one summer, I found that they kept several areas of pond ice-fee in the winter - so I didn't bother with the heater after that.

[ARWadsworth]

Why not just put some antifreeze in the pond................................