Diatoms And Bba


Junior Poster
Feb 10, 2015
My new 20 Long low tech has been set up for a few months and I'm starting to get brown diatoms (know this is usual for a new tank). The issue is I'm also starting to get very tiny tufts of BBA. The photo period is 6-6.5 hours using a Finnex stingray which should be between 35-40 par with a glass top.

Was wondering if it could be a lighting issue or something else. I did receive some plants with a tiny amount of BBA that I didn't fully kill. Is it possible that it's just spreading from the original source?

For prevention of BBA, I turn the lights off after a water change to prevent fluctuating co2.

I'm able to reduce the par further to around 20 with window screen. Not sure if my crypt parva will do well at that level though and was worried that the diatoms will thrive further in lower light.

Currently trying to kill it off spot dosing excel

Fauna: crypts, anubias, marsilea


New Member
Jun 26, 2018
Seems like you have answered you own questions. Bba could have come in on plants. Keep dosing excel. And try manual removal.
This all depends on stocking and feed and ferts.
That’s said, it still a new tank at a few months old.
Best of luck.