May
It's a standard tropical tank, 165 litres with 8 fish. We do a bi-weekly 1/3 water change including vaccuum. We've had the tank about 8 months and this is the first time it has happened. It doesn't appear to be bothering or harming the fish, but it looks bad, and it's growing swiftly. What should I do?
Answer:
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 most common method of controlling this type of algae is introducing the siamese algae eater fish - this is the only fish known to feed off this algae. 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 totally cleaned it. But even these astounding 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 huge amounts of BBA, the BBA covered leaves should be removed once the phosphate level is controlled.
The best way to eliminate BBA is to let the plants out-compete the algae for the nutrients by artificially increasing nitrate concentration by adding potassium nitrate into the tank.
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 grant 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.
First of all, don't think about 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 superior 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’ll 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.
If you mix 2 tablespoons of KNO3 into 250ml of water, each ml will add .72ppm to a 30g tank. Begin off adding 1 ml everyday. 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 math 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 advocate starting with a dose that’ll add 5ppm over a week.
Note: Many dechlorinators and aquarium plant fertilizers come in 250ml bottles. That's what I use to mix mine.
Bleach is not good for your tank.
Never use it in your tank unless you consult me.
It contains Sodium Hypochlorite. This is deadly to your tank and your fish.
Remember the improper use of bleach will kill your fish and all live bacteria living in your tank.
Answer:
I would suggest more frequent water changes, as this is almost certainly black beard algae, which thrives on high levels of nitrate and phosphate as well as excessive lighting. More water changes will remove nitrate and phosphate, and cutting back the lighting to only a few hours a day will be an effective combination.
If you’ve fake decorations or rocks, bleach actually isn't a bad idea. A 50% bleach solution can be used in a big bucket to kill the algae with a 3 hour soak. After the soak, rinse the decorations until you can no longer smell bleach, then let them air-dry for 24 hours (this will fully neutralize the bleach).
Black beard algae: http://www.floridadriftwood.com/brush_al…
Answer:
Bleach.