Ive been FF for quite a few years in rivers and streams but would like to do more lake fishing. Got a new float tube but know little about sinking lines. Was thinking about getting a good intermediate sinker like the Rio Aqualux and something a little heavier for getting deeper. What kind of lines so the lake fishers around here use? How deep can you fish an intermediate line?

As far as intermediate, you can't go wrong with Cortland clear camo. How deep depends on how long you want to wait. I use a Type II and a depth charge 250 along with my intermediate all the time. I also have a Type V. These are all density compensated, but I have a type III wet cell for weedy places.
If I was only going to have two sinking lines I would say an Intermediate and a Type III, and count down if I need to get deeper.

She gave you good advice there, Anthony.
Another thought is whether you would like to mess around with shooting heads or not. My reasoning on this is that when I really need to sink one, the V type head or heavier seems to get down pretty quickly and the head system seems to keep it deep without porpoising up on retrieve.
If so, then a floater, a Type II and a V or VI would probably get it done for you, depending on the rod line weight designation.
FWIW, with heads I usually go up at least one when choosing. i.e.- a "8 wt" classed head for a 7 wt rod.
Dewey

Deweywh, You are right on adding shooting heads being a good thing. That is why the depth charge is probably my favorite. 30' of lead core and 60' of intermediate. I can put leeches on the bottom quick and when retrieving they run straight like a real leech instead of up and down. Great for crawfish also. But you have to get the right grain for the wt of rod. As recommended by Jim Lepage: 200 grain for 5wt and 250 grain for 6wt.