I used to overflow my 200g goldfish pond to clear surface debris but my 2000g koi pond this doesn't work at all. I put the hose in and it overflows in one area at the end, but nothing on the surface flows over there. I have a skimmer and another pump I'm putting in so it's not a huge deal, but I'm really confused about why this doesn't work. Is it just simply the volume, my garden hose isn't fast enough pumping to make this work?