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Black algae? What to do...
Posted: Tue Jul 26, 2011 12:53 am
by Hike
I'm trying to get my tank in order but I have this black algae/something growing on my java ferns and my decorations.
When it grows on the plants and I let it go it peels off in sheets.
I'm sure my ammonia and nitrites are zero but I'm not sure what my nitrates are until I get a new test kit.(soon) Is there anything else I should test for? Any suggestions on what I should do to get rid of this?
Re: Black algae? What to do...
Posted: Tue Jul 26, 2011 2:05 am
by xrayjeeper83
Cut back on lights. I assume this is a puffer tank so snails wont last long lol. Other then that just pull it out yourself
Re: Black algae? What to do...
Posted: Tue Jul 26, 2011 8:46 am
by Iliveinazoo
Re: Black algae? What to do...
Posted: Tue Jul 26, 2011 7:10 pm
by Hike
xrayjeeper83 wrote:Cut back on lights. I assume this is a puffer tank so snails wont last long lol. Other then that just pull it out yourself
Not a puffer tank but my Bolivian Rams have wiped out my snails.
The black color makes me think it's more like the Black Brush algae on the same page you linked to but even the pics of the BBA aren't quite what I'm seeing.
Re: Black algae? What to do...
Posted: Tue Jul 26, 2011 9:40 pm
by sevenyearnight
Does it have a strong odor?
Re: Black algae? What to do...
Posted: Wed Jul 27, 2011 12:04 am
by Hike
sevenyearnight wrote:Does it have a strong odor?
Not that I've ever noticed.
Re: Black algae? What to do...
Posted: Wed Jul 27, 2011 12:51 am
by Hike
Ok, if it's needed i did a few tests after picking up a new nitrate test.
Nitrates ~ 5 ppm
Phosphates ~ .5 ppm
Ph 7.2
kh ~ 3dKH
Not sure if the last two help diagnose the issue but I did them anyway

Re: Black algae? What to do...
Posted: Wed Jul 27, 2011 12:54 am
by Hike
Hit submit too quick...... now I just need to figure out if it's the black brush or the blue green since both have different courses of action to help get rid of it.
Re: Black algae? What to do...
Posted: Wed Jul 27, 2011 8:34 am
by Iliveinazoo
Hike wrote:Hit submit too quick...... now I just need to figure out if it's the black brush or the blue green since both have different courses of action to help get rid of it.
The fact that it peels off leads me to think that it's just a thick layer of blue green algae.
it could be a nutrient/light issue but it could also be flow, since my small pump broke I've noticed a slight increase in the BGA build up in my tank
Re: Black algae? What to do...
Posted: Wed Jul 27, 2011 9:20 am
by RTR
From the description, it dies not sound like BBA to me.
Do you have a GH test kit? it might help diagnose the issue.
Are commercial buffers being used?
- if commercial buffers are in use, discontinue immediately and throw them away. Do 2-3 50% partials to purge them out.
- I ask that as your KH is quite low, but the pH is higher than than that KH would give.
Is this tank heavily planted and/or nutrient supplemented with plant nutrients routinely?
- The phosphate is 'way high, which is unusual in routine FW tanks except those using commercial buffers or inappropriately giving too much PO4 to the plants. The N:P:K ratios normally should be about 7-10 to 1 to 7-10+ (those figures are based on N, P, and K alone not NO3 and PO4 ions.. Your phosphate is much too high and that does promote algae growth.
-What is your water change schedule on this tank?
If you are supplementing P/P04, cut the supplement to one tenth the current use and do a couple of back to back 50% partials to reduce the PO4 levels.
There are thousands of algal forms in the world. The one that your tank chemistry favors is the one/ones you get.
HTH
Re: Black algae? What to do...
Posted: Wed Jul 27, 2011 3:01 pm
by Hike
RTR wrote:
Do you have a GH test kit? it might help diagnose the issue.
Yes, just didn't think to test last night.
Are commercial buffers being used?
- if commercial buffers are in use, discontinue immediately and throw them away. Do 2-3 50% partials to purge them out.
- I ask that as your KH is quite low, but the pH is higher than than that KH would give.
No. My KH is always low. Soft local water I suppose. In the past I have used crushed coral to help keep the KH stable.
Is this tank heavily planted and/or nutrient supplemented with plant nutrients routinely?
- The phosphate is 'way high, which is unusual in routine FW tanks except those using commercial buffers or inappropriately giving too much PO4 to the plants. The N:P:K ratios normally should be about 7-10 to 1 to 7-10+ (those figures are based on N, P, and K alone not NO3 and PO4 ions.. Your phosphate is much too high and that does promote algae growth.
Plenty of java ferns but I wouldn't go so far as to call it "heavily planted". The only thing I supplement is Flourish Excel. If the phosphate is high I would have to guess it's from the tap since I don't add anything else. I did a change Sunday night.
-What is your water change schedule on this tank?
About 25% once a week currently.
There are thousands of algal forms in the world. The one that your tank chemistry favors is the one/ones you get.
So it seems.

Re: Black algae? What to do...
Posted: Thu Jul 28, 2011 12:30 am
by Hike
approx 5 dGH RTR. (assuming I'm doing the test correctly)
Re: Black algae? What to do...
Posted: Thu Jul 28, 2011 8:07 am
by RTR
GH tests are pretty easy. You are likely correct.
Have you ever called your water utility? They are one of the very few govt. functions who like hearing from their public IME, and they tend to be very helpful, especially in the US, as they are required to be or they get in trouble. You might ask them if they add phosphate buffers to the water before it enters the pipe network. A lot of soft-water areas do that to protect the network.
Java Fern is a good plant, but quite slow-growing and metabolizing, It is not very hungry.
The next time you set a new tank, try aragonite substrates rather than crushed coral. They are more soluble and would buffer your water better. But it would not make a big enough difference to justify changing the current substrate out.
You might try boosting the water change volume and see if that cuts the phosphate.
There are also phosphate removal resins which do work, but the are not cheap and have to be replaced when loaded. They also are not very good on planted tanks, as they might remove too much phosphate. It is a required macronutrient for plants. If all else fails, you could give it a try and see if the cost of running it periodically is worth the result you get. I have used Phos-Guard with success.
That is not very helpful, but about the best I can offer.
Re: Black algae? What to do...
Posted: Thu Jul 28, 2011 12:06 pm
by sevenyearnight
Perhaps you could add an easy to maintain, fast growing plant, liked water sprite, maybe it might use up some of that phosphate?
Re: Black algae? What to do...
Posted: Thu Jul 28, 2011 2:19 pm
by Hike
sevenyearnight wrote:Perhaps you could add an easy to maintain, fast growing plant, liked water sprite, maybe it might use up some of that phosphate?
Could be on to something. Back when I had Water sprite I never had an algae problem. Who knows.
RTR, I can find out if the water company adds anyting. Maybe I'm misunderstanding but wouldn't larger volume water changes add phosphate if the source of the phosphate is the tap water?