i think this is the right place to ask this i have two koi and my house has been very cold it tends to stay cold around 50 or so the heater i got dose not keep the water warm enof even with it turned all the way up and left for 3 days. so i picked up some hikari wheat germ for lower temprature feeding iv been useing the hikari gold for color since i got them. can i change there food just like that or how should i do it there feeding time is in 4 hours... ps im getting another heater next week when i get money