How much flow for a cycling tank?

[DEL 707]

I setup my 56l which has a nero 3.

Overnight I got a crater in my sand.

Do I have too much flow? At the moment the pump is set to 40% constant speed, the app says that's about 1190 GPH.
With no fish or coral, I'm having a hard time telling if it's too much or too little.

 

[TeamAquaSD]

I setup my 56l which has a nero 3.

Overnight I got a crater in my sand.

Do I have too much flow? At the moment the pump is set to 40% constant speed, the app says that's about 1190 GPH.
With no fish or coral, I'm having a hard time telling if it's too much or too little.

Probably a little too much however you can definetly make it to where a rock takes some of the flow to help mitigate any excessive flow.
I believe that should help immensely