Re: Dark algae beneath gravel

Hi Paul and Cindy!

<<The dark algae is probably a mixture of bluegreens (Cyanobacteria).  I see
it all the time, too, ...>>

I really don't have any measurable nitrates and only see the bubbles 
every few days so really haven't worries about it too much.  I am sure 
it is not good, these bubbles, but there are so few.

<< looked up hydrogen sulfide in the Merck Index (a reference book for 
chemistry) and it said it smelled like rotten eggs.>>

I haven't noticed any smell at all but with so few of the bubbles, it 
would really tax my nose to smell anything<g>.