Brown spots on white gravel / substrate

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TTUHoopsFans

Aquarium Advice Apprentice
Joined
Jul 22, 2020
Messages
23
Hi Everyone,

New aquarium owner here of a 40 gallon cube type tank. The tank has been running for about 11 days or so. We did the turbostart and also have added stresscoat / quickstart, etc and checked the water levels before we started slowly adding fish. We now have 5 zebra danios, 3 neon yellow danios, 3 otocinclus, and 3 cory catish. Yesterday, we started noticing some brown spots on the white gravel. These came about a day or two after we added the otocinclus and cory catfish -- we were told to feed them algae wafers once or twice a week until our tank starts building enough algae for them to eat, and I guess the catfish will also eat any other remaining fish flakes that fall all the way down to the bottom? I think we may need to get a pellet type food for the catfish that sinks? Anyways, getting off topic -- our question is what are these brown spots -- is it a brown algae? Is this normal? There were a few algae wafers down in these general spots at first but the fish eventually consumed them slowly, and pretty much all of the fish in the tank were into them. Thanks in advance!
 

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Brown algae or more correctly diatoms is perfectly normal, especially in a new tank. They are actually a tiny creature, not an algae. Their main source of food is silicates from the sand and rocks you have put in the tank. These silicates will eventually be consumed and then green algae should out compete the diatoms and it should die off on its own.
 
Brown algae or more correctly diatoms is perfectly normal, especially in a new tank. They are actually a tiny creature, not an algae. Their main source of food is silicates from the sand and rocks you have put in the tank. These silicates will eventually be consumed and then green algae should out compete the diatoms and it should die off on its own.

Thank you so much, this is very helpful!
 
Thank you so much, this is very helpful!
When your tank is properly cycled and all the nutrients get into some sort of balance, it should clear up on its own. In the meantime, while unsightly, it is harmless. From recollection, last time i had diatoms they disappeared a couple of months after the tank was cycled. Some people recommend turning up the lights to clear them up quicker, and i believe otos will eat it, but probably not off the substrate.
 
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