I'd be fairly certain the light is the issue here. T5 HO tubes are quite intense, compared to the older T8 type. Get some floating plants, and consider reducing the light period. I have to keep my tanks at 8 hours max, even with T8 tubes, or this algae becomes a nuisance.Thanks Byron for your reply. I have a 50 gal tank which is about 19" deep. The lighting is 2- 28W T5 NO 6500k bulbs that are on for 10 hours per day. I dose once per week with Flourish comprehensive. I do a 30% water change weekly.
Yes, that is likely. Slower growing plants attract this stuff more.Thanks, The T5 lights are normal output, not the HO ones. I will cut the duration down to 8 hours and see if that helps. I did buy some water sprite a couple of weeks ago, but it only covers less than 1/4 of the water surface right now. I have noticed that only the lower leaves of the Bacopa have the algae on them. The upper 1/2 of the plants are algae free. Perhaps that is because the upper portions are rapidly growing, whereas the lower parts are not?
You can leave the leaves; the brush algae is very difficult to remove, but you can pull some of it off when the plant has tough leaves like Anubias, but this isn't necessary. The important thing is to correct the cause so it does not spread. And with Anubias, this usually means putting the plant in indirect light, not direct overhead light. Remember too that daylight from a window can add to the "light." And not over-fertilizing also can help though with Anubias it is usually the light.I have it, a bit darker, on a large anubia and a few (now cut off) leaves of a java fern... I have absolutely avoided cutting off the large leaves (2) effected by this algae on the anubia but am afraid that it will spread further - it's better shaded now than when the black spots first appeared - so my question is: is there any alternative to trimming this very pretty and otherwise health plant back or is it a must to get rid of this stuff???