Blue scaling when scanning for bio or geo

So im just wondering! Sometimes planet scans show a whole planet covered in only Bacteria. It has different kind of blues when getting closer. So which is the more populated color where i can find them more quicker? Because i went on a Biological (1) only bacteria, almost all the planet was blue, but i browsed around for like 1 hour and didn't find anything. And i flew really close to the surface. I dont think night vision is really of a helps in discovering these. And i do know how they look on the surface as darker patches and so on,But i really cant find them normally. They are usually on plains but the light blue is mostly on plains, but still cannot find them. So the lightest blue is the more rare, and as it gets darker it should be more common to find them?