yeah sand is good i haev it and my polkadot loaches and hoplo cat love it! the hoplo filters it through his gills which is wicked as it keeeps it clean
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i have a 125l tank and i think i used about 3.5 bags of 5kg white sand.That was purchased from the fish store so i knew oit was safe! although.....are you planting in your tank? as i did and you would need a stronger substrate underneath to root the plants! ???
you have to be careful with these kind of things. i had a disaster myself but with sponge 
Using Play/silver sand from a garden centre is usually the cheaper option... As long as you clean it well before placing it into the aquarium, there should be no problems...
thats a safer option!