Iron (gravel or food containing iron) + Phosphates (fish food ,dosing routine) + Light are what supports Diatoms & all other Algae.
Iron: water source,fish food,other source?
Phosphates: dosing routine, over feeding easily results in P resources in the tank.
Light: photo period & intensity are what you need to try to adjust? what are you using & how long?
Diatoms will NOT disappear using Black out method.only slow them.
they are one of the 1st creatures on our planet,millions of yrs of evolution.
to starve them out balance of the above 3 is what is required.
If your plants are under nourished (resource limited)then they will struggle with iron & P uptake the diatoms can easily consume them.(ex EI dosing method supports limitation of resources for plant growth,which revolves around C02.)
lowering lighting and/or photo period will help plants become stronger & limit what's left over for the diatoms & they will decline.
even if you sterilize everything that has ever touched the inside of your tank the spores are airborn so they will readily re-inhabit any supporting enviroment with out being spread by the user.
the general concensus that they will disappear by them self's is misleading for those who'm have that experience their tanks have reached a Better equalibrium which resulted in the diatom;s Apearing to disappear,when in fact the tank still has them,however tank conditions presently wont support noticible amounts.
hope that helps.
