how hot is your water and you may have to put up something to shade it for now .But a foot and half may not be good enough for the winter unless you can get pond deicers .Now is the time to get them ,they are on sale .You will need an oxygen pump also .How cold are your winters and do you have predators that could get your fish .I put a shade sail over my pond .It was cheap and you can take it down .Does your electric go out in the winter because that could be a problem also .Does your pond freeze over in the winter .Alot here who live in cold states have basement tanks for there fish in the winter