Lighting help

I just realized I think my lighting is a bit off. My Temps are ok with a 160 watt mercury vapor bulb and a 60 watt household bulb. However I am also using a repti glo UVB tube. So I realize this might be too much UVB with the MVB and tube, right? Of it is too much should I simply replace the mercury vapor with a normal basking lamp? Of so, what wattage should I buy?

My tank is 36" long, 18" wide and high. There is a mesh screen on top and the tube is mounted on the inside.

Which MVB are you using? The 160w ones are usually pretty powerful and should be kept at around 10-15'' up. Probably closer to the 10'' mark if it's shining through the mesh top which will intercept a bit of the UVB. It's hard to say for sure without measuring with a Solarmeter. Which ReptiGlo tube do you have? How far is it set from the basking area?

I have the same sized tank and use a T5 Arcadia UVB tube and a GE 90w PAR38 halogen flood light mounted over the tank suspended from an adjustable stand and that works really well for me.

It's an exo terra solar glo which I've read don't really put out an insane amount of uvb anyway which is why I wanted to supplement with the fluorescent light. I'd say the tube is about 20 inches from the basking spot. I'm thinking since the MVB is a less powerful one it might actually be ok to have them together but I'm not 100% on that. I've been researching all day. The solar glo is about 14-15 inches away. I haven't been able to find current numbers about the uvb output. Do you know where I could get a decent priced solar meter? Also the target amount of uvb is right around 130-150 right?

The repti glo is an 18 inch 10.0

OK so that's a T8. Is it in a fixture with a reflector? If it is then it may be useful at around 6-8'' but won't provide much beyond that or if it doesn't have a reflector.

The latest test results I have from a 160w Solar Glo show it not producing very much UVB but I'm not sure if that's widespread or up to date. http://www.uvguide.co.uk/UVTool-ExoTerraSolarGlo160W.htm
Using a Solarmeter would give you a better idea. You can sometimes find deals on them but they generally run about $200 or so. I like to shoot for UVI between about 3-6 over the basking zone and a gradient down to 0 in other areas of the tank. If you are measuring UVB directly it's usually around 150-200 uw/cm2 over the basking area.
Generally I prefer using a T5 tube for UVB so that can be set at an appropriate distance and I can control the heat independently.