Solar Ice melter

[dhaslam]

Fish get  trapped below the ice  for long periods and if there are no gaps for gas to escape and oxygen to enter they can  die.   Sun is usually strong in frosty periods but the angle is wrong  to melt the ice.  Breaking the ice  could injure the fish.    Any ideas to  save having to use kettles of boiling water?     It would be relatively easy to generate solar heat upwards  but to transfer heat down  to the ice is a bit more tricky. 

[MR GUS]

I guess dh you would be thinking of a floating platform with upper insulation in place / suspended slighly above the ice to keep the heat introduced firing downward? ..would any heat simply not be absorbed by the large area of cold frozen surface & cold beneath?
Perhaps a sealed heat ball? weighted,  & directional a take on the old floating football ice gap for ponds..
if it were to be via a small tube array?? then you are looking at hosing to circulate pre-heated water, therefore a semi permanent (seasonal) set up of a few tubes insulated up to the eyeballs, stabilised & a power supply to back up & recirculate?
I guess a ball shape to constantly heat a very small area between pumping out & replenishing with  hot.
Big job, or a small heated wire array that melts stuff & floats / can be kicked out across larger areas & hauled back via it's electrical connection.
Guess it's time once more for someone to highlight the risk of water, lectrickery & expensive fishes? ..however, what do commercial fisheries do?

[djh]

Put some soot or ash or even soil on the ice. It absorbs the sunlight better.

[dhaslam]

Good idea about the upper insulation.    I suppose, to take it one step further,   the side away from the sun needs to be insulated as well  with the  south facing side painted black.    If the container is airtight the  warm air should  go below the water level as well.      I never found the football idea any use, all you get is a frozen football in the ice but perhaps  the colour is important, same effect as soot.      

[MR GUS]

Dh, would a small constantly moving agitator paddle not work more favourably in terms of upper surface so it could be merely skimmed of semi solids? at least in an area of the pond if not the whole of it.
Not that I know, just thinking...
Over to the experts

[guydewdney]

salt 

solar panel and 12v kettle element?

[dhaslam]

For the present I just want a fairly simple device  to keep the fish alive.    But for the new pond I will do something a bit more sophisticated.   Possibly I will use a small  hot air panel  like the ones  for the heating system and blow air through it into the water  which will both aerate the water  and melt the ice.   Using a small PV panel would mean it could run all year whenever there is sun.

[Baz]

It looks like your solution from the photo is to bury 4 bodies. If these are politicians I thnk it will work as they must have enough hot air stored in them to last several winters.

[billi]

It would be relatively easy to generate solar heat upwards  but to transfer heat down  to the ice is a bit more tricky. 

just a fast thought about these words brought me to the idea to ram / bury  upright pipes in the pond ground ( hope it is not lined  ) to transfer warmth from below freezing point towards the ice shell

As well some plants like bullrushes  would help (but invasive )

Blowing some warm air with a small air pump into the pond would do as well

Billi

[fatbob]

Hmm I am sooo tempted to suggest some angled mirrors to increase the efficiency of a solar solution, but in the interests of the season of peace and goodwill, let's not go there eh....