black algae all over plants in my RBP tank

[maudsley]

hi guys can anyone help me,

i have tested water and all results are perfect but
i have started getting this black hair like algae all over my plants and its started on the rocks, wood and filteration pipes aswell. so this wk end just gone i totally stripped all wood rocks out, binned all plants as i can not clean the algae off them without damage. hoovered all gravel. the re planted tank with new plants and re decorated. i have fears that this algae will come back though. my set up is,

55gallon/190ltrs corner unit
fluval 305 external filter
x2 T5 lights on for 7 hrs a day
undergravel fertilizer for plants
rocks, bogwood
6 red belly piranhas

 

[HarleyK]

Howdy,

i have tested water and all results are perfect

Would you care to share nitrate, phosphate, iron, pH, gH and kH hardness, and conductivity with us?

x2 T5 lights on for 7 hrs a day

How old are your bulbs, and why only 7 h/d? Dark algae is generally a sign of poor water in combination with extremely poor lighting. Considering you have substrate fertilizer for plants, I assume your tank is planted? What species? How are they dealing with only 7 h/d light???

I'd get new bulbs specifically for aquatic plants, and increase lighting to 12-14 h/d. Plus regular water changes, of course

HarleyK