*Dear Mods, new here, not sure which forum this belongs in, move as you see fit, thanks!* I've noticed that there are many posts that mention the need to rinse stuff like sand and gravel thoroughly before adding it to the tank. Usually the methods suggested involve putting the stuff in a bucket, add water, swish, pour, repeat. With enough rinsings eventually enough of the finer particles are removed to put your stuff in the tank. Time and energy consuming and the results still aren't perfect. May I suggest a better way I've learned? Years ago I learned how to collect and refine and purify a mineral called magnetite, a black iron ore sand that collects in low spots in dry river beds in the desert. I collect it with a powerful magnet and remove it into a bucket, then take it home to process into a refined and uniform, mineral collectors grade sample worth paying money for. The particles range from very course (like the lowest grit sandpaper made) grit to super fine dust like pastry flour. What gets collected also has some non-magnetite dirt and dust and sand and clay mixed in with it. My goal is to remove all that is not magnetite, get it super clean, sterile (why sell local riverbed microorganisms to mineral collectors in stuff they'll handle), and of a super uniform particle size. I'll skip the parts of the process related to magnets and just talk about the fastest and most effective way to get finer silt and dust and mud level stuff out, leaving only the "sand sized" grains you want. At first I did the same as described, rinse swish pour repeat, but soon realized that the finer the particles, the more they want to stay on the bottom, and no matter how many times the swish pour method is used, at the bottom of the container there will still fine particles, too heavy to stay suspended in water long enough to pour out. There is a very fast and effective way to get WAY more of what you want gone from sand and gravel than the swish pour repeat method. Perhaps if you don't need to do this very often the following is way too much trouble (and it will cost a small amount of money too) and swish pour is adequate. However, if you want a way to make your sand/gravel SUPER clean (so minimal cloudiness and wait time to clarity), PLUS, get that stuff EXACTLY to the fineness or coarseness you want, and extremely uniformly so, here's how. Check out this supplier of stainless steel wire meshes: Determine approximately the fineness of the material you want at the end of the process based on the photos of their mesh. Buy a minimal sample of meshes above and below that sample's fineness in one square foot size. *The quality is fantastic and these things last forever. You may find uses for this mesh beyond aquarium uses!* When you get the mesh, see if you guessed right about the size that will do what you want using the material while dry. Figure out how to make a container with the mesh size you wantat the bottom. Pour in what's getting cleaned (not too much at once, small batches go faster and in the end more time efficient). Pour in water (helps to not hold the hose etc and work with both hands, and swish it around as the water pours over it. Smaller particles will want to go to the bottom, and if smaller than the mesh go through immediately. The very finest particles (the dust/dirt/clay stuff you want out the most that makes the water cloudy till it settles) are gone fast, whereas with the bucket swish pour method, they'll stubbornly stay at the bucket's bottom no matter how many times you repeat. With this method, you can see when the last of the fine silty/dusty part has GONE and you're DONE. This method once refined, gives you material that is both super cleaned (AND if you use two meshes next to each other in size, precisely sized per your needs). This companies mesh ranges from 1" (small actual rocks) all the way through #635 (would actually filter water kind of well and get clogged fast removing stuff, have experimented with a koi pond filter, catches algae like crazy and clogs right up (did not end up using for that!)). Since I already have their mesh I'll be doing this on the next tank bottom material I use. PS To truly sterilize the material, I cook it in a very heavy iron pan on the stove way past the temp ANY organism can survive, rather than use chemical methods. Overkill but certain.