when I clean out my pond or top it up in the summer I use a hose off the tap but do 2 things. First I make sure that the water gets agitated as this drives out some of the chlorine. If I am filling the empty pond, I do it with some force so the water sprays around , if topping up I use a sprinkler head. I also get stuff from the local pet shop to add to the water to remove the chlorine and coat the fish to protect them...can't remember what its called now but the pond shop or petshop should know. Make sure you buy a pond sixzed one as its sold for fish tanks as well in much smaller amounts and is much dearer that way. If I am cleaning out the whole pond then i put in a bacterial kick start and treat the fish with antiseptic....just done a web search, I use Aqua Safe and medifin by Tetra because that's what i can get locally, other ranges are available, they generally say you shouldn't mix them