The main causes of algae are typically excess phosphates, excess light, or poor water quality. Lights should be on no more than 10 hours a day, and the water needs to be maintained. Healthy tanks might have a very thin layer, but not one that grows quiclky.
Depending on how long you have your lights on, it might be a good idea to cut the time down a little bit. That used to be the problem with my tank.
Yeah, lighting really does have to do with algae thriving in a tank... If you have plants, depending on what kind they are then lighting shouldn't be under 8 hours, but not over 12 hours. If you do have plants, try not to exceed less than 8 hours, if anything break down the time so it has an hour break in between light hours (ex. 4 hours light, 1 hour no light, 4 more hours light). If you don't have plants, then yeah, lights aren't very necessary xD So you can go below 8 hours just make sure they're not on too long... Where's your tank located? Is it getting any kind of sunlight as well and do you know what kind of bulb you have that could possibly be encouraging the algae growth?
Once you find a sweet spot for less algae growth, the main thing that helps is elbow grease. Just make sure you lightly scrub everything (the walls and decorations) with, say, a toothbrush it will definitely help keep algae at bay... Chemicals can definitely hurt your fish and plants if you have them....
Okay, just wondering. Usually with plants it depends on how many kelvins and watts a bulb has. I wasn't sure if you did or didn't have any plants to know whether or not the amount of time your light bulb was on would make much of an impact on your tank... But it doesn't seem like it would be too huge of a difference, so you're good! ^.^; Also, algae can survive in either low OR high light intensity, but thrive better in low light conditions with no plants to compete for nutrients. So if the algae growth still seems pretty dominant even after adjusting the time frame of the light, then getting a more intense bulb seems like a good idea as well..
Maybe more frequent water changes and/or less food for your fish since algae thrives on the nutrients that your fish builds up- which the two main nutrient sources for algae is nitrate and phosphate (which is created by your fish and the bacterial digestion of foods. Not trying to say you feed your fish too much, but since it wasn't mentioned there is that slight possibility that I'm not aware of so I figured it was worth bringing up).
Also, what's the pH level of your water? The lower the pH (say 6.5-7.0) the more likely plants (including algae) are likely to thrive. It's because there are more molecules accessible to convert ammonia to ammonium and that provides more food for things like aquatic plants/algae to grow on. With higher pH, molecules are more likely to convert to ammonia instead of ammonium (which ammonium combines with hydrogen to create 'food' molecules like nitrogen. There's more hydrogen in lower pH and that's why it turns into ammonium rather than ammonia and 'produces more food'). I'm not saying you should change the pH, but it's a factor to take in that might also be helping the algae thrive. It's more like one of those "the more you know 'cause knowledge is power" kind of statements >.>;;
Thanks for all of the info! Yes, it is good to know all possiblities.
Well, I think that I'm just now maintaining the tank like I should, so hopefully the algae won't be a problem. Not sure about the pH, I'll have to check, but if the algae does get bad, I'll definitely check the things you've mentioned. Thanks, again!