Very nice job!! ..and that Frog definitely likes you ..lol
Where on LI are you?
Ok, you do NOT need a heater (per se) in a pond in the wintertime, you only need a device like the one linked above to keep an opening in the ice for gas exchange, so get a heater like the one I posted (on line is much cheaper than local stores for this item!!)
Likely the pond will not freeze all the way to the bottom at the depth you have yours (mine is even more shallow although it is about 2,000 gallons and (knock wood) I have lost no fish over the past umpteen winters on the South Shore.
Do you have a thermometer in there? You need to stop feeding your fish when the water temp reaches about 50 degrees as they cannot digest below those temps. Do NOT resume feeding them again until Springtime when the water warms to about 45 + degrees on a consistent basis...not even for a day! They will stay fairly motionless for the winter and will stay at the lower depths of the pond.
IF your heater ever fails to keep an opening in the ice - do NOT break the ice - the shock will kill your fish! Instead use hot water to melt a new opening (place a pot of near boiling water on the ice until it melts through - don't drop that water into the pond...) and replace your heater. Best to take a peek at the pond each day to make sure everything is going ok over the winter
You also can take your filter off line for the winter as any of the beneficial bacteria in there will not stay alive in the cold temps. You also do not want to circulate the water as the point is - the water at the lowest depths will be the warmest (the fish can deal with it!)..and then every few inches (for example) the water temp drops a little until it reaches just under the ice..and then the ice itself..and we know what the temp is there! Circulating the water will only make the water colder all the way to the bottom of the pond..and you don't want that.
Did I over answer your question? lol
:fish: