Bog question.

[ashirley]

The bog has been running for a few weeks. The water is clearer than it has been in a long time; however, there is a brown sludge building up on surface of the gravel. It looks like dead algae. Is this normal? Should I try to remove it? I am thinking of trying to vacuum it off with a shop vac.

 

[brc]

I suspect there won't be much you can do about that, besides covering it under plants. You've got shallow, nutrient rich, well aerated water with light hitting it - something is gonna find a way to grow there!

I think you could also add more gravel on top so there's a dry upper layer that'll stay clean.

 

[poconojoe]

I agree with BRC. More gravel on top. Or...have your water outlet spilling lower into the pond. Basically attempting to keep the water level lower in the bog.

 

[Timothy]

That's just the bog doing it's job. If you cover it with more gravel the sludge will still find it's way to the surface. The next time you cover it up the higher the sludge until the sludge will just recycle through your pond. There's likely to be some beneficial critters (tads) living in that layer as well.
If it's offensive I think I'd just put in more broad-leafed plants to disguise it, then when the bog gets congested with roots cull the plants.