Substrate grain size???

[trelise]

Hey guys. Still planning my 20 gallon. Now looking at substrate a little more.

I have picked a substrate with 2mm grain size.
There is a cheaper option with grain size of 0.5-1.0mm. Is this too small, will the grains be blown around?
I will be using a powerhead in the tank, either a tunze nanostream 6020 (if it comes back in stock) or a fluval sea cp2.

Does this substrate look okay? https://www.hollywoodfishfarm.co.nz/product/aragonite-2mm-25kg-sack-4/

 

[flagg37]

2mm is good. Obviously if you stick the power head right by it it can kick it up but it’s much less likely to be blown around than the .5mm size.