Posted: 19/06/2012 at 18:52
Your fish should be fine as the top of the skimmer bobs up and down with the water level and stays on the surface. Our pond had koi, goldfish and fry - plus the usual assortment of pond skaters etc - and you can't get more curious than koi and they would have a look when it was on and that was it. Unless they jumped in then no worries. Besides, they would be caught in the basket and not get all the way to the filter.
We would push our oxygenating plants into the water and wiggle them a about a bit and the duckweed etc would just float out. If you feed your fish don't do it before you skim or all the food will go down the skimmer (obvious really).
We used to have another pond which was pristine - no soil, minimal plants etc so that the koi were living in crystal clear water - a system which a lot of koi enthusiasts prefer - and we had a skimmer which was specially made for the job plus a shed load of filters and pumps. I wanted a more natural pond but we installed the bottom filter system before thinking about a skimmer so came up with the swimming pool idea.
Someone should invent a fish which only lives on duckweed and then there wouldn't be a problem....