Cycling Tank Question

[Yellow Jobber]

I set up my 75 gal tank recently and decided to do the cycling the tank with out the use of fish method as described in the article on this site. I used two jumbo sized shrimp which have been in the tank for about a week. I have 120lbs of aragonite sand bed and about 40 lbs base/live rock and will be putting more in soon. My question regards the brown deposits that are forming on the sand bed, glass, and rock. Ammonia is still only at about 1 ppm. Whats the deal with this brown stuff? It wipes right off the glass pretty eaisly and dissipates into the water.

 

[SeanMurphy]

Possibly a diatom bloom. Not sure what color marine diatom algae is, but it's definately a dark brown color in my fresh tank when I first set it up. This should go away once the initial bloom gets under control. I think it's caused by the huge influx of silicates that suddenly get added when you put in new sand.

 

[Kurt_Nelson]

Just a normal diatom bloom that happens during/after a cycle. They'll burn themselves out eventually. Once your ammonia and nitrites get to zero, get some trochus and astrea snails - they'll make quick work of the diatoms. Until then, it's just one of those "rites of passage" on your way to a saltwater tank.

 

[Yellow Jobber]

Should I be cycling with the aquarium lights on or off?

 

[roka64]

On or off doesn't really matter, but it may help to keep algae blooms in check. Other than that, it sounds like your normal cycle.

 

[melosu58]

As Scott said I would do it with out the lights as to keep the algea down. As far as the cycle it really does not matter.