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Cheyenne2747
A month ago, I set up a 470-liter aquarium + a150-liter sump. I added approximately 25 kg of coral sand from an existing aquarium and about 40 kg of live rock. The lighting consists of 8 T5 lamps at 54 watts, with a 9-hour photoperiod. Two weeks ago, brownish-greenish circular spots appeared on the substrate, which later evolved into a uniform brown coverage across the substrate. In some areas, there are bright yellow spots. When the substrate is disturbed, the coverage rises in the form of a cloud. Could you please advise me on what this is and how