The algea you are describing sounds more like diatoms. The main culprit will be the introduction of silicates, usually through the use of tap water or RO
only water sources. In a tropical climate, silicates will be much more prevalent due to the higher temps. If you are able, try getting an RO
system with a Hi-S cartrige. That will help in reducing or eliminating it. The only way to be sure is test for the silicates.
If the RO
is unatainable, using a quality PO4
granular sponge will help alot.