Tank Cover

	I have a 125gl tank with Discus, angels, Tetras and some Golden snails.  The tank has been in operation for approx. 6 Months.  I have it fully planted and have only fair plant growth.  I have several questions.  Listed are the Specs of my system.
	Temp-81 Deg
	Eheim wet/ dry canister filter.  Using spray bar against back of tank, very little surface agitation and minimal bubbles.
	Fluval canister filter with outlet hooked to a sandpoint co2 injection system.
	I have two pendent MH lights suspended about 8 inch over the tanks, 175 Watt each.
	My tank is open on top.
	Dupla Laterite and # 1 Gravel over this.

1.  Would I have better plant growth in general with a glass cover over the tank?

2.  I recently added Angels and they seem to always be  on the surface.  Could this be to much CO2 or do they usually hang on the surface?

3.  I have a small algae problem and recently added 6 Golden Snails.  They seem to be doing a job, but I am worried that they may eat my plants?

bob at cyberia_com