Red algae: Also called Black Beard Algae (bba), or Black Brush Algae. Short hairs (1/4" long), closely packed together. Appears dark green, black, or dark red. Grows on plant leaves, and sometimes on decorations/substrate. Often grows all around the edges of plant leaves.
BBA thrives in situations of high phosphates. Phosphates come from fish waste, excess food, and occasionally will be present in the water supply. The best way to eliminate BBA is to let the plants out-compete the algae for the nutrients.
In heavily planted tanks, BBA will often show up when the plants have used up all the nitrates. This causes plant growth to slow or stop, which leaves the excess phosphates available to the algae. By supplying extra Nitrate to a planted tank, we allow plant growth to continue until all phosphate is consumed. Then plant AND algae growth will slow/stop. As long as a usable (5-10ppm) level of Nitrate is maintained, the the plants will continue to use up the available phosphate, effectively controls BBA and other phosphorus-dependant algaes. See the article "Adding Nitrate to a Planted Tank" for detailed instructions on how to increase your Nitrate levels.
Very few fish will eat BBA. The most famous one is the SAE (Siamese Algae Eater). I've got 5 of them in my 75g. I added several BBA infested stems of Bacopa to the tank recently, and overnight, the SAEs had completely cleaned it. But even these amazing fish won't be able to control it you don't have the phosphate level under control. Another fish rumored to eat BBA is the American Flag Fish. In tanks with very large amounts of BBA, the BBA covered leaves should be removed once the phosphate level is controlled.
Adding Nitrate to a planted tank
First of all, don't consider adding any nitrate unless you've tested it, and are sure it's zero (or very low, less than 10ppm). Make sure your test kit is accurately measuring Nitrate. Many nitrate kits won't register low values. My AP Dry-tab kit doesn't show anything below 20ppm. Good results have been reported using the Red Sea nitrate test, and the Seachem nitrate test.
Second, ALWAYS MAKE CHANGES SLOWLY!
To add nitrate to a planted tank, most people use KNO3, Potassium Nitrate. It's available at some better garden stores, farm suppliers, and hydroponics suppliers. It's also the ONLY ingredient in "Green Light Stump Remover", sold by Ace Hardware (and some other home-improvement stores). Not all stump removers are pure KNO3. Use other brands at your own risk. Several plant enthusiasts have contacted the makers of "Green Light", and have verified with the chemist that it's pure KNO3.
The desired nitrate level is 5-10ppm.
For dosing, let me repeat again, make changes slowly. A nitrate level of 10ppm wouldn't hurt any fish. But if your level is zero, and you add enough in one dose to raise it to 10ppm, you will kill fish.
Here are the numbers I've got for dosages. If someone out there sees an error in my numbers, please let me know. I'm not very good with chemistry. These calculations were derived from info provided at The Krib.
If you mix 2 tablespoons of KNO3 into 250ml of water, each ml will add .72ppm to a 30g tank. Start off adding 1 ml each day. Over a week, this will add 5ppm of Nitrate. Test after a week. If it's still too low, increase to 2ml each day. Keep repeating this until you measure 5-10ppm.
The maths isn't tough, but here are the numbers for some other size tanks: (21.6 divided by your tank gallons = ppm per ml added)
10 gallon : 1 ml of above solution adds 2.16 ppm
20g : 1 ml of above solution adds 1.08 ppm
30g : 1 ml of above solution adds 0.72 ppm
40g : 1 ml of above solution adds 0.54 ppm
55g : 1 ml of above solution adds 0.39 ppm
75g : 1 ml of above solution adds 0.29 ppm
So, I suggest starting with a dose that will add 5ppm over a week.
Note: Many dechlorinators and aquarium plant fertilizers come in 250ml bottles. That's what I use to mix mine.
Used without permision from Chuck's Planted Aquarium Pages
