water level

Subject: water level

> 	I've seen a lot of planted tanks that have a really low 
water l
> the top of the tank. I'm guessing thats for either light penetra
> Am I right, or is there another reason?

The higher your lights are above the water surface, the more light 
you lose.  To optimize your lighting, the tank needs to be as full 
as possible.

As far as gas exchange is concerned, as long as the water isn't 
directly in contact with the cover so that you limit surface area, 
there should be plenty of gas exchange.  You don't increase 
surface area by lowering the water level.  

The only reason I can think of to keep the water level down in a 
planted tank is if you have floaters that would be adversely 
affected by condensation falling on them from the hood, and/or you 
want some of your plants to become partially emergent.

Personally, I prefer to have the water level high enough in my 
tanks that you can't see the water line.  It saves a lot of work 
removing lime deposits!<g>

Karen Randall
Aquatic Gardeners Assoc.
Boston, MA