Ok this will be purely my own personal view/experience. Not sure if everyone agrees with me.
Reasons that causes algae growth? Water source, frequency of waterchange and feeding.
I think the above 3 are the main reasons why algae grows.
-Water source are just too important. If you use the wrong water from the wrong place, then don't even need to mention frequency of waterchange and feeding. As non purified water has got just too much materials in it, it can be anything may be even human waste??? So RO
water is a must. But even you have one you might need check if it work properly, filters replaced etc etc... otherwise there is no point getting a unit. I have been buying bottled deionization water and only top off with them. I previously use tap water caused me cyano
problems and has since gone when I started using bottled water. But I am currently looking getting one RO
unit myself as I have just set up a new 132g tank.
-No matter how pure your water is, over time your water will become dirty and need to be changed. If this is dragged on too long waste will build up and could encourage algae growth. So frequent water change is a must. I change the water for my 20g nano EVERY week, never missed. I am also planning to do 10% waterchage every week for my new 132g.
-Over feeding your fish also contribute to algae growth. Uneaten food will be the main source of food for algae. So only feed your fish that is enough for them to consume. I always throwing food little by little into the tank and watch my fish consume them and make sure no food able to reach the bottom before it is consumed.
So IME stick strictly with these 3 principles will almost guarantee you will have no algae problem. Anytime when you have algae problem ask yourselves these 3 questions. Hope this can help someone out there who is fighting algae problems.