Black algae

[bgk245]

I have a 25g community tank that has been all but overrun with black algae. The tank has 5 red-tail rasboras, 5 black neons, a krib and a bristlenose pleco, plus a moderate collection of plants - lots of java fern, a sword, one anemic cript, and until recently, two anubias. I say recently because the plants were so algae-covered that they were dying. I could not clean it off without damaging the leaves, so I tossed one and cut the other back to just the healthy growth.

There are a number of large rocks, most of them covered in black slime, along with a goofy looking skull cave my kids picked out when they were little (I can't take it away, it's been the pleco's home for years). I can scour it off with a wire brush, but it comes back. Even the top layer of gravel gets covered with it. I just did a water change and major cleanup, and it's not too bad now, but give it a week and it will be returning, hairy in some places, slimey everywhere.

Any suggestions? Water parms are generally ph around 7.3, 0 ammonia and nitrites, 10 nitrate, moderate to hard water, same as it's been for years. Filter is an AC 30, and there's an airstone in one corner - I put it in a few months ago to run a corner filter with extra charcoal while I had an exterminator out, and found the pleco likes it, so I just left the stone running. But the onset of algae problems predates the extra O2. It's just gotten worse in the last month or so.

[bgk245]

So the complete lack of answers means I'm the only one who ever had this problem, right? :) Or just that no one else has any ideas that work, either?

[rolloffhill]

:hehe: wish I could help ya, never had that problem.

[kewlkatdady]

how long has the tank been set up?

Did you change any of your lighting or the time the lights are on?

[poel_19]

how long do you leave the lights on??

[bra8ndy8]

Mine is doing the same thing........soooo I can't help u. I can tell you my lights are on about 8 hrs.....and it's been set up for over a yr. And I have tons of algae eating guys.........

[bgk245]

Tank's been set up for about 4 years and change. The problem started in small amounts about 6 months ago. I had some DIY CO2 running at that time (yeast, sugar, baking soda), but that had been going on for about a year, and taking it off (about 4 months ago) didn't make any difference. It has a double bulb fixture, but that's still low light - less than 1.5wpg, on a timer that leaves it on about 12 hours a day.

I'm considering getting a couple of otos in there to see if that helps. Goodness knows I have plenty of goodies for them to eat.

[AndrewH]

(Of course I reserve the right to be wrong about anything :D)

From my understanding, the black algae is one of the bad ones because nothing will eat it. Also, algae seem to thrive on extra nitrogen in the tank and lighting.

My personal suggestions would be to reduce the lighting. Since you have live plants they need at least 8-10 hours of lighting, so I did a 4 hours lights on, 2 hours light off and 4 hours lights on schedule to combat my algae problem with great success. The theory is, plant start photosynthesis as soon as the light comes on, while algae take 4 to 6 hours to begin. Staggering the lighting should kill the algae while allowing the plants to stay healthy. On my tank, this method did take a while to work (3-4 weeks).

Another solution would be to black out the tank for 3-4 days. Zero lighting getting to the tank will kill any living plant or algae, so I would only recommend this as a last option, or if you removed the plants you want to save before hand.

Another option you might want to try is getting a large, full grown plant which requires lots of nutrients (the swords come to mind). The idea is that the sword would use any nitrogen in the tank before the algae can get it.

Besides the black out options, most of these solutions will take a while to start working.

Also, you might want to keep an eye on your nitrAtes as the plants need them for food. If they drop any lower you'll start having problems keeping your plants alive without a food supplement.

[AndrewH]

Also, does the tank receive any direct sunlight?

[AndrewH]

Here's a good read you might find helpful.

"Our Wonderful Tap water (or Things You Don’t Want to Know)
Almost all municipal water treatment facilities treat our tap water to kill algae, bacteria and protozoa before it is filtered and delivered to our faucets. Not all of the chemicals that are used get filtered out. On any given day, our tap water may contain fluoride, iodine, chlorine, chloramine, and traces of: potassium permanganate, magnesium sulfate, nickel sulfate, copper sulfate, various heavy metal-nitrate complexes, as well as pollutants such as lead, PCB, mercury, and silver nitrate. Yummy! More of these chemicals are used during the fall and spring when temperature changes cause a phenomenon called "Biannual Turnover". Temperature fluctuations cause the water at the bottom of lakes to rise, carrying silt and anaerobic material up into the water collected for our use. All of the chemicals used in tap water can be toxic to fish.
Although a good portion of our municipal plumbing systems have been modernized, nearly all of them still have old lead pipes in-line which can create deadly high-lead levels in our drinking water. The cost of replacing these pipes is astronomical, so another solution was found. Several years ago, water treatment plants started introducing a phosphorus compound into our tap water which binds to the lead in the pipes and coats them so that lead does not get into our water. Unfortunately, this has had the bad side-effect of creating rather high levels of phosphates in tap water. We have tested levels of over 0.50 parts per million in our tap water. Our test kits only measure up to 0.10 ppm, and we have had to dilute our samples by as much as ten times to achieve accurate readings! This high level of phosphates in the tap water has been a major cause of rapid algae growth in aquaria for the last few years. We lower these levels considerably by using phosphate-removal filter media in your external filter. However, every time you change the water, you actually add more phosphates to the aquarium. If the city uses more phosphorus from time to time, the algae can grow back almost immediately after your aquarium is cleaned."

[bgk245]

No direct sunlight, and I tested for phosphates last night and found it close to 0, though I know from sorry experience that the test readings on local tap water are something of a crap shoot on a day to day basis. I nearly killed off my fish one weekend trying to fix an ammonia problem by doing water changes til I figured out that every time I did a water change, it RAISED the ammonia level.

But I scavenged in the kitchen drawers and found 2 more pins for the cheap-o timer on the lights, and it's now running 4on-1off-4on, so we'll see how that does.

I've heard both ways about nitrates and algae. Some people swear the problem is high nitrates and recommend more plants, and others swear it's the reverse - that if your plants use enough to let nitrates fall below the 10-20 range (which is about what I usually have), THAT's when algae gets out of control.

[kewlkatdady]

I can't make the "low nitrate" arguement make sense.

I have some plants in my 58 shellie tank and the nitrates never get about 10ppm. There is very little algea in this tank.

My 125 has fake plants and the nitrates are ALWAYS over 20 and most of the time around 40 ppm's. There is algea EVERYwhere.

[biggin]

I agree with KKD....

[bgk245]

I agree that it never sounded reasonable to me - I can't figure out how depriving a tank of nutrients would somehow increase an organism's growth, but I do know fishkeepers who swear by it.

[biggin]

I know fish keepers who say fish will only grow to the size of the aquarium and that the stunted growth is natural and healthy.... Seems equally as silly to me.

I agree that it never sounded reasonable to me - I can't figure out how depriving a tank of nutrients would somehow increase an organism's growth, but I do know fishkeepers who swear by it.

[bra8ndy8]

yeah I heard that too! but jaws outgrew 3 tanks! silly!