[Lupin]

It's normal. It will settle in a matter of hours although minutes is possible since you said it is clouding slightly.

 

[Lupin]

I would assume similar for using a substrate for plants? Go into the gravel almost to the depth of the substrate?

I just vacuum the gravel once a week around the plants. The plants don't like frequent movements around their roots and bases. I rake the gravel so the detritus will appear making it easier for me to vacuum the detritus out.

oes that get to be a pain?

I have to admit sometimes it is.:lol:

Also (hopefully not going too far off topic), can you add substrate to a tank that already has gravel in it? How?

Yes. Just go on adding the substrate although I don't like the idea of mixing gravel and sand together.

Reason for editing: Spelling corrected.