Thanks Dan Pruett, for your support of Marineland products! Algae is caused by excess nutrients, so you need to determine why you have this issue in order to eradicate the algae. When you vacuum the bottom of the tank, make sure to take out 10- 20% of the water. Don't take out a lot since you are vacuuming weekly. Taking too much could disturb your biological filter. Also, test your ammonia, nitrite, and nitrate levels. They should be 0 for ammonia and nitrite, and less than 10 ppm for nitrate. Test both your tank and your tap water to compare them.
You mention it is a new tank, that you are changing water once a week, yet it is green two weeks after the water change. This doesn't compute. Make sure you are not over feeding. If the tank is about a month old, feed once a day, one piece of food per inch of fish, at most. Make sure all food is eaten in 30 seconds or less, and none has time to drift down to the gravel.
Next, add some Marineland Bio Spira Freshwater Bacteria to get your biological filter established. Do this after a water change, and then try to not do any water changes at all for at least a couple of weeks. And last, make sure the lighting is proper for your tank. Don't leave it on more than 8 hours a day, and make sure the tank is not near a window or glass door.
Date published: 2017-09-28