Although there are a number of actions one can take, the two most effective starting points in the algae war are first to play around with your light hours and second to increase your water currents. I use two photoperiods, morning and evening, so we can view the tank with light most of the time we're around to enjoy it but also give the plants enough hours of light to grow without going too much on the light and encouraging the algae. One experiment I tried on some brown diatom algae was just to take away one of the hours from the morning photoperiod. I got lucky with that and noticed a pretty good reduction in the amount of brown algae.
The least number of hours I've heard used is 4, which I've heard mentioned as a starting point for new tanks with the intent to increase it slowly after the plants begin a healthy growth. The largest number of hours I've usually heard of people using is 12 or so (other than people trying experiements) and most of the things I read have people trying things at 6, 8 or 10 hours, amounts like that. Its a balance of course between giving your plants enough but not giving excess that the algae will take advantage of.
The business of increasing water currents has to do with the fact that algae spores are triggered to begin growing by the presence of small pockets of water that is more still and has relatively more ammonia in it. The amounts of ammonia involved in this are not detectable by our test kits, so its not up on the same level as what we worry about for the fish. Some people augment the flow created by their filters with standalong powerheads of various sorts, often placed lower in the tank to help stir up dead zones in the deeper parts of the tank. Some planted tank hobbyists even use filter flow rates of 10x and more to help combat algae.
Anyway, I think of those two as a couple of the practical methods probably most accessible and effective for beginners to be able to do something but its always good to remember the fundamentals that algae can rarely compete when there are a lot of strongly growing plants in the tank and that usually to get strongly growning plants like this one would need a significant source of CO2.
~~waterdrop~~
