Hi John,

I got it from is thousands of miles away
and I only have just over 3KG of it.


My guess would be 5g aquarium.


I actually plan to add a layer of Flourite underneath


Perhaps if the sand is for some reason very special to you it would be
better not to mix it with anything...(?)


There is a chance I could always have a slightly bigger tank than it
would cover and just be innovative with the space it won't cover by
adding other things.


That may be wise as it is easier to maintain a bigger aquarium. Good source
of information is an often recommended website http://www.thekrib.com/

--
Regards,
Marvin Hlavac
Toronto, Canada