Sand
Absolutely. Once you have your filters running and the tank clear, you will need to cycle the tank. This can be done easily by adding flake food daily to the tank as a food source for bacteria, or by adding straight ammonia to the tank every day… It will take 3-4 weeks before the tank is fully cycled and ready for fish. Here’s some links of interest in regards:
http://faq.thekrib.com/begin-cycling.html http://www.gpodio.com/food_cycling.asp
As for the cloudy water from the sand, as others mentioned you could use a diatom filter, they work great. I haven’t used mine in so long now I don’t even know where it is 
I find I can usually take care of any such need by using filter floss or micron pads in the existing filter, or “quick filters” if needed. I guess I’m getting more and more lazy these days If all fails, perhaps try a flocculant to help filter the small particles out. I think with time it will all get filtered out one way or another, just depends how quickly we need it to go away
Hope that helps Giancarlo Podio, LMD
Category: Philippines Internet Koi Society
