Originally Posted by Nathan_Drake
But if you want to kill the nitrate cycle then clean it with a tooth brush
That is not true at all. Cleaning algae will not negatively impact the nitrogen cycle. Nor will cleaning the bacteria off of decor.
Brown algae is diatoms, which are quite common in newly set up tanks. Many algae eaters will eat diatoms, as will snails. Diatoms are very easily removed from whatever they are growing on - even live plants. You can wipe it off plants, and use a toothbrush on decorations, as was mentioned.