There's three yoyo loaches (2" each), three green cories (2" each), two albino cories (1" each), two juli cories (1" each), and two female bettas (2" each).
I actually put filters over the lights to dim. The issue is the algae growing on the plants. It isn't growing on the glass and gravel, and it's actually enhancing the appearance of the drift wood. It's primarily growing on the fake Amazon sword.
Nitrates, ammonia ... everything is perfect (I do a 20% water change every week, and gravel cleaning once per month ... Penguin 170 in fine shape). But, brownish Amazon swords are not appealing. Granted, it takes a month or more for the algae to become a distraction, but I'm not going to buy a live one as I don't particularly like plants. So, back to question ... a simple additive?