We could use more information so that we can better help you. If you want, let us know:
How old is your tank? When did it originally cycle? Has it cycled since then, again? Why?
What kind of system do you have (tank volume, dimensions, bio-filtration method, the equipment you use, any carbon or other chemical filtration, kind of substrate, etc.).
List all specimens & sizes in the tank (fish, inverts, corals, clams, snails, crabs, shrimp, etc.). Indicate to the best of your memory, how long you've had each.
If you have a refugium and/or sump, what is living in it?
Do you use a quarantine tank and procedure?
Foods you use and feeding schedules.
Do you use any vitamins? Fat additives? Any elemental or other additives? Please list all.
Chemistries ââ"šÂ¬Ã¢â‚¬Å“ please give actual numbers (Ammonia, Nitrite, Nitrate, Phosphate, Silica, Ca, Alk., and any others you have)
Water parameters ââ"šÂ¬Ã¢â‚¬Å“ please give actual numbers (pH and your pH range, salinity or sp. gr. & range, temperature range)
Do you see any of the following in your system: hair algae; micro algae; cyanobacteria growths; dinoflagellate (zooxanthellae) growths; brown algae; diatom growth; slimes; colored patches on rock or substrate; etc.?
List what you added or taken out of your aquarium system (living, decorations, and equipment) during the past 6 weeks.
Maintenance schedule. What have you done lately?