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black stuff

  1. General Reef Discussion
    click to enlarge When I bought this rock the dealer had no clue as to what it may be...they said. And they move ALOT of rock even on the internet. Said it may be a type of sponge, but it has no intricate spherical tube work as the little pink sponges around it does. Rather it is velvet like...
  2. General Reef Discussion
    Tests Nitrate 0 Nitrite 0 Phosphate 0 Ammonia 0 pH 8.2 I get this black stuff on the top of the rocks. I can blow off the rocks and will form over macro algae and other thing in the tank. My only 2 thoughts are my lights are too old for algae to grow (original bulbs from tank set up) or...