Hi thc420. Appreciate the concern and the advice.
As SketzoH points out, I use very small pots so having a handle on what the roots are doing is most beneficial.
I do think the whole thing about keeping roots in the dark is an old wives tale though which is why I wouldn't bother covering them up.
Hopefully the plants speak for themselves in terms of general health, but if you think about it, roots are destined to live in blackness so it's highly unlikely that they have any means of even detecting light.
The only problem that is likely to arise would be from algae forming as happens when you leave a cup of water on a windowsill for a long time. As I let the plant dry out, and I can see for sure that it has dried out, this can't really happen. As an insurance measure I do boil and then filter my water after leaving it to stand though.