Ok, I bought a bag of sand, I sorted it with a mesh strainer to get the bigger stuff out and then I rinsed the smaller stuff to get all the dust out and to get a bunch of the really tiny particles out.
The sand will be for plants and for Kuhliis. I am not worried about the Kuhliis as they will love whaetver sand I get but I am worried about it compacting and suffocating the roots of the plants.
The Q is:
How do you know for sure if the sand will compact or not? I know what beach sand does and how it feels. Is that what I am looking for? Do I want to let the sand sit in water for a day or so and see if I can easily put my fingers into it to the bottom, will that mean it should be plant safe?
Eventually I will just buy the right sand but when you have $10 to spend and get enough sand to do everything you need I am more than happy to do a little more work to get it.