What substrate to use?

[shadowstars123]

You might have to diffuse the output if it pushes it around alot. I've never had an issue with this but I use canister filters rather than HOBs. HOBs also push sand around so people often stuff more filter floss into them to diffuse the flow, or make a DIY diffuser.

If it's cloudy then you have two choices, either let it settle or do a water change. When you are adding water back to the tank, use a plate or a bowl to spray the water onto so that it is not stirring up the substrate.

I know the plate method. I use canisters too, how do you diffuse it other than a spraybar?

 

[jetajockey]

I just have my outputs pointed parallel to the surface of the water, it doesn't disturb the substrate at all.

Depending on the kind of canister there are several diffuser attachments available, but I've never really run into an issue of the substrate being moved except when using a HOB and having that whole waterfall effect.