Removing algae from a fish tank is one of those never-ending chores that's part and parcel of keeping a healthy aquarium. Algae are microscopic organisms that float free in the water or grow on aquarium walls, ornaments, plants and other surfaces. Algae can be green, red, purple and other colors, and they grow in a range of forms including threads, patches and water discoloration. All fish tanks have some algae, and usually they affect only the appearance of the tank, but excessive algae growth can be harmful to fish.
Brown algae is a common occurrence in a newly set up aquarium
Anyway, I have a fluval edge (6 gallon cube tank) set up for shell dwelling cichlids. I'm using the stock halogen lighting, with crushed coral to keep the ph up. The fish are very happy and are successfully reproducing... problem is I cAnnot control the green algae. Water tests are fine, I did a 50% water change multiple times and move the tank far from any natural lighting. Any idea? I just stripped it down, and again the algae is back within 2 days. Thanks!
What Causes Brown Algae in Your Fish Tank?
Like all life, blue-green algae require nutrients to grow, reproduce and survive. They are particularly fond of nitrate and phosphate, but other compounds that can build up in the water, like ammonia, will do just fine. Increasing your water circulation is a good start, as is preventing uneaten food accumulation and cleaning your substrate regularly. Also, make sure your filter and protein skimmer are working well and that you're cleaning and maintaining them as the manuals tell you to. Remove dead fish or plants from your tank right away; they quickly start to decay, a process that gives off the nutrients you need to keep in check. Don't forget the all-important partial water changes; replace 10 to 15 percent of your tank water every week or two to help maintain appropriate nutrient levels.
10 Easy Ways to Control Algae Growth in Your Aquarium - Pet Education