[cfox29]

I have a 29 gallon fw tank. I have had plants in my tank for a couple of months now. I am dosing dry ferts for macros, flourish comprehensive for micros and glut as a carbon source. No pressurized CO2. I have a finnex planted + light that I run for 7 hours daily.

I do 50% weekly WC. My water parameters are good. Ammonia and nitrites always zero. Nitrates at 5 ppm (I just increased my nitrates dose this week to try to get up around 10 ppm. My phosphates are at 1 ppm.

My plants have done well. Growth is slow because I have mostly slow growing plants, but they have been healthy. My ferns, however, have always seemed to have these black areas/spots (pictured). I think they have been present ever since I received them (ordered online); I don't think they are any better or worse. So, is this typical for this plant or is it a sign of a nutrient deficiency or other problem?

More recently, I have seen the tips of a few leaves start to turn a darker green. This can be seen on one of the pictures just below the filter intake (a smaller leaf tip). Anyone have any idea of what this is or means?

Thanks in advance.

 

[cfox29]

Thanks for the opinions. What about the darker green leaf tips? It is hard to see on the second picture (which is rotated for some reason) just below the filter intake. Any idea about this change or is it more of the same java fern idiosyncrasy? My primary concern is whether this could be cyanobacteria, although I have never seen this.

 

[cfox29]

I am dosing potassium and I don't think the dark spots are falling off and leaving holes.

In regards to the BBA comment, the spots are not a "growth" on the leave. It is more a part of the leave itself, if that makes sense. Not saying it can't be BBA, but just an additional description.