What Do You Think, Another School?

[cuticom]

So I'm bored, was just wondering what you guys thought of my current tank stock, and whether I could get away with another of school of tetras? the tanks been running for well over a year, well the fish and filters have anyway, this tank broke a few months back but was replaced the next day so there was no cycle.

The current stock is
8 Serpae tetras
4 Black Widow Tetras
3 Kuhli Loaches
1 Platy
1 Corydoras
1 White Cloud Mountain Minnow

I'm going to bump out most of the schools so the stock will be
8 Serpae tetras
7 Black Widow tetras
6 Kuhli Loaches
6 Platies (1m, 5f)
6 Corydoras
1 WCMM

The WCMM was given to me with a bunch of decorations, and can't say I'm a fan of it so am just going to let it live its life out without adding more.

The tank has sand as the substrate, a few lucky bamboo plants growing out the top, planted in a glass vase the kuhlis hang out in, as well as a basketball sized piece of java moss and rapidly growing wisteria and java fern. So I was wondering if I could get away with adding one last school of eight or so tetras? even though it seems I have a lot of fish, the bioload seems very low, during last term i was pretty slack on water changes, but apart from some extra algae everything stayed stable, nitrates were barely at ten.

Opinions?

Thanks
Emma