What is the best way to take phosphates out of water? Is there a special type of filter media, or does plain activated carbon do the trick? The reason I ask, is that I am having a slight algae problem. I am 90% sure the phosphate levels are causing it. I have a planted tank (not heavily planted), the plants have done a great job with the nitrates (5 ppm, currently) but the phosphate levels are still around 4 ppm. Is this high enough to cause the algae to out compete the plants? I have read that the trick to algae control is a balance of nutrients, am I just not balanced? I do weekly 20% water changes. I have cut back on feeding.
Part of the problem is the tap water. According to my tests, the tap water has levels of 1 ppm. I checked the test using distilled which read 0 ppm, as it should.
So what is the best way for me to remove the phosphates?
Algae killer is not an option, since it is not fixing the problem, just the symptoms.