Brown Algae

[fort384]

So, I have defeated the dreaded BBA, vanquished the BGA... but now I am starting to have brown algae problems. It has always been there, but it was much more manageable. As of late, it grows rapidly on the aquarium glass and it is taking over my anubias, and even starting to spread to my crypts. From the resources in the sticky in this forum, it seems like the problem is perhaps too many Nitrates or Phosphates, or perhaps my lighting cycle is too long (I am currently lighting the tank for 10.25 hrs per day).

My issue is, I do not want my plants to become N or P limited, so it seems contrary to good fertilizing methods to lower these numbers (nitrates are between 20-30ppm and P is <.1).

When I was keeping my N below 20ppm, I was having BGA issues. I wonder if I should shoot for 15-20ppm instead of 20-30 ppm?

I have a powerhead in the tank that is keeping the water moving near the bottom pretty well, so I don't think flow is the issue.

Also, the back wall of the tank has grown up pretty think with the brown algae -- I have a lot of tall plants in the back so it is barely noticeable. My theory was (or is) that if I let it grow back there, it will use some nutrients, perhaps limiting its growth in more conspicuous places. Is this the case, or would it be better to just brush it all off? It comes off rather easily with a magnetic algae cleaner or a toothbrush, so removal is not a problem.

CO2 has been in the 20-50 ppm range, I am using CO2 injection, so I don't think that is an issue.

Any suggestions?

 

[Purrbox]

I'd recommend leaving your Nitrates alone and bumping your Phosphate to between 1.5-3ppm. It's probably an imbalance between these two rather than an excess of either that is causing the issues. You might also try to keep the low end of your CO2 levels above 30ppm. This should help too.

 

[SpeedEuphoria]

What kind of lighting do you have? and what size tank?

I highly suggest reducing your lighting down to 8hrs a day as that is likely at least part of the issue

I have been doing minimal dosing and using low CO2 levels on my 55G for a couple months and everything is doing great unless I slip on the dosing(wait longer than 4days). So far I dose the EI dose for a 20-40G tank every 3 days and things grow like crazy w/ just a ODNO shoplight, 8hrs a day. So my setup is ~100w of T8 lighting w/ limited reflectors, and 1-2 BPS of CO2, then dose once every 3 days according to EI for a 20-40G tank, the reason for this is so I dont have to do 50% WC's every week, I only do 20-30% WC weekly

 

[fort384]

29 Gal, 2.6WPG. Breakdown of the specific bulbs listed under "my tanks".

 

[SpeedEuphoria]

Yeah w/ T5's you have high light, not sure what type of reflectors/fixture you have but its still high light either way and 8hrs max should do just fine.

 

[fort384]

Purrbox,

I did as you suggested and bumped P up. Seems to have worked great. I cleaned all the brown algae I could out about 2 days ago, and it has not returned.

Thanks as always for sharing your wisdom.