Hi Lisa,
Have a look at the nearby brown algae thread where I've made some comments about brown algae.
All algae (in the setting of our freshwater hobbyist tanks) is caused by excess light and excess ammonia. These are the two things that can be sometimes brought into balance to achieve a beautiful algae-free tank. I say sometimes because it must always be remembered that algae are normal, natural and healthy in natural ecosystems and since you are trying to create a healthy ecosystem for your fish and vascular plants, you are creating the right conditions for healthy algae too. Some beautiful underwater scenes that are photographed and give us our impressions of freshwater beauty might actually be naturally covered in algae if they were photographed at other times of the year!
The most powerful control of algae is that of restricting the tank lighting hours. Most of us do that with simple lamp timers from the hardware store. I like the mechanical ones so that you don't have to bother with batteries but remember that noise can be a problem with cheap lamp timers if you have them in a bedroom. Try to plug one in while in the store and put it to your ear. Of course, even before the timing consideration, any situation of sunlight falling on the tank should be dealt with - things are easier to control with less overall room light and no direct sunlight hitting the tank.
Vascular plants (the live plants you are trying to grow that are not algae) (non-planted tanks should not receive extra light beyond family viewing periods) need a minimum "photoperiod" (continuous stretch of tank light) of 4 hours. Less than 4 hours is not enough for the complex biochemical machinery in the plant to get going and produce sugars and structural fibers and so just promotes algae and not plant growth. So 4 hours, 6 hours, 7 hours, 8 hours, maybe 9, maybe 10 are the photoperiods that hobbyists play with. If you are free of algae problems then longer hours like 10 or 12 may even have advantages because that more closely matches the real tropics where these plants and animals come from, but unfortunately it is extremely hard to also copy the high water flow and enormous filtration that natural systems have, so our tiny systems usually are more prone to algae problems.
Even though all algae starts the same way (excess light and ammonia promote algae spores to break into active algae) it is not all dealt with the same way. In fact, once it has been correctly identified (not always easy) then each type of algae will have a special way that hobbyists have learned to deal with it (and there is always the possibility of new ways.)
The planted section has a set of resource articles called the "PARC" and in there you'll find pointers about algae types and links to a great site by one of the planted members so you can try specific remedies if you need to. The planted members also have spent much greater focus on knowing about these things so a thread there may bring forth good info!
Besides lighting hours, good water change habits and substrate and filter maintenance habits can make a big difference both because actual algae spores are removed from the tank and because lowered traces of ammonia removes the other necessary cause of algae breakouts.
~~waterdrop~~
