Definitely Cyanobacteria. Trapped bubbles give it away. Here is a link that may help ALOT!
Sudden Algae Outbreaks
Algae outbreaks can quickly overtake a tank, grow over and kill corals and other livestock.
Algae needs three things to grow: light, nitrates and phosphates.
If you see a sudden algae outbreak, one of these three things has changed. Reducing nitrates and phosphates is of one of the greatest challenges of marine aquarists.
Prevention: Reduce nitrates to under 10PPM and phosphates to zero! The methods for reducing these chemicals are numerous but the best ways are:
Install good protein skimmers.
Use refugiums with plenty of macro-algae and a very strong plant light.
Regular water changes.
Do not overstock. Know how many inches of fish your tank can handle.
Use cycled live rock which is an excellent filter.
Do not overfeed.
Nitrate and phosphate reactors use chemical media to reduce these chemicals.
Use reverse osmosis (RO
) or de-ionized (DI
) water only. Test your RO
water with a Total Dissolved Solids (TDS
) meter because filters may become prematurely worn out and lose effectiveness. Use of tap water has caused many algae outbreaks. Tap water often has phosphates in it and charcoal filters will not remove phosphates. One person used a garden hose to fill his tank with tap water. The hose had copper fillings which are deadly to invertebrates.
If an algae outbreak occurs but nitrates and phosphates are near zero, consider that these two algae nutrients may be settled in the rock and sand but not in the water. If so clean the rock in tank water (not tap water) and let snails, gobies or starfish sift the sand.
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