safe grain size of sand/gravel?

[RoseFishWatcher]

Hello!

I have recently discovered that the definition of sand and gravel has a very fine dividing line, and that "play sand" size can vary a ton depending on location.

I want to use sand that is about 2-3 mm, but I'm not sure this is safe for my Senegals. Any idea how fine the sand needs to be to be safe?

 

[toehead11183]

im sure any size would be fine. ive noticed that folks on here use sand fron very fine to course sand.