I used a round transparent tubing of 8mm in daimeter to do the siphoning. The amount of water draws out at every feces cleaning is around 10% to 20% depending on the sizes of the tanks. If I do the cleaning daily, I wouldn't be performing weekly water changes then ! Last but not least, when you do your water changes please use aged water treated with anti-chlorine. I'm using the below anti-chlorine.
Besides doing regular housekeeping, I guess food plays another part in the beauty of the fishes as well. Here's a list of flakes and granules that I used to feed the guppies. Twice a week I do supplement them with tubifex worms !
