In article , harry k wrote:
Water levels are a great tool and is the only way I know of to level
around a corner but need some care.

1. The entire line must be in the same condition, i.e., all in sun or
all in shade.

Utter nonsense.

2. There can be no air bubbles in the line.

If you fill it the way I described, there won't be.

Personally, I would use a laser for the OP's use. They are not
expensive and will be used many times if the OP does much carpentry
over the years.

Phooey. Even the "cheap" ones are an order of magnitude more expensive than 35
feet of vinyl tubing, and they're MUCH less accurate. With a steady hand and a
sharp eye -- and a sharp pencil -- it's easy to get +/- 1/32" with a water
level. Ever look at the specs on the consumer-grade laser levels they sell at
home centers? Typical is +/- 1/4" at 25 or 30 feet; I saw one at Sears a few
years ago labelled as "accurate within 1/2%". That doesn't sound too bad until
you do the math: that's an error of an INCH AND A HALF at 25 feet. To get the
kind of accuracy with a laser level that can be easily achieved with a water
level, you need to go beyond consumer-grade units to professional gear costing
many hundreds of dollars.