How much space between H2O and cover

[cometcattle]

How much empty tank should I leave between the cover and the water?

This would be for a 10g and a 5.5g.

Thank You

 

[Silly me]

doesnt matter.. lower would be better for getting as much as possible light in the tank, it is always harder to get enough light in these small tanks.

if its higher you might have some plant growing out of the water and flower but you'll need to make sure there's enough light in the tank