Utilitarian fish for small frag tank

[Hats_]

I have a Reefer 350 for which I converted the integrated ATO reservoir to a frag tank. yet i have been pestered by hair algae and small harmless flatworms for a while now. I have a single Trochus snail and some stomatella snails in there and for the most part they do their job fine but i have been debating on either, moving my sixline wrasse down there, get a mandarin dragonet for it or maybe a blenny like a tailspot but i am open for suggestions.

below a picture of the frag tank, i think it was about 10 liters in size, i have some frag racks in there and some rock rubble. there is also a small SLW-5 wavemaker in the back of it at the bottom. also the place is teeming with pods and flatworms.

 

[Lavey29]

I wouldnt put a fish in a 3g or less ATO tank. Get an Urchin or two and a few more snails.