I don't vacuum my tank but just replace the water because I thought that vacuuming the gravel would take all the nutrients out. to vac or not to vac that is the question : P
In my lake malawi tanks where there is no plants I clear the tank out and vac every inch.. however my 10g is a planted tank where I keep my smaller sized peacocks growing out, and I do the same as above, I vaccum everywhere except where the plants are to keep from bothering the roots of the plants.
I have no idea, as I don't do that. I vacuum, as enough nutrients will get into the roots to keep the plants alive. Pretty much everything I vacuum up is going to end up turning into excess nitrate in the water.
well, there is a lot of food and fish poo/wast that falls to the gravel that you get up when you vaccum... I would recomend if you don't vaccum at least moving the decor around and stirring up the gravel and let the filter get the stuff.
I vacume all of my tanks on a regulat basis, and would not recomend doing anything else. The purpose of vacuming the gravel or sand is to remove excess waste from the tank that can cause an increase in amonia and nitrates. As for the concern for removing nuetriants and good bacteria from the tank, as long as you have a good filtration system with a biological and mechanical filter system on it you will be fine.