Who Gives A Fish Forums

If you're still worried about residue, consider running a polyfilter in your filter. It's designed to remove a wide range of contaminants.

First, rinse the tank thoroughly with dechlorinated water. Bleach and Harpic contain harsh chemicals that can linger. Use a 1:10 vinegar solution to scrub the residue, then rinse again. Test the water for chlorine and other contaminants before adding fish back.

If you're worried, pool filter sand is a safer bet. It's uniform, pre-washed, and designed not to mess with water chemistry. Costs a bit more, but saves the hassle.

the sucker fish looks like an albino chinese algae eater to me.

as for the others, they're a mix of cichlids - there are just so many varieties out there, it's tough to pinpoint the exact ones from just pics.

**** edit - didn't catch that you already mentioned they were cichlids, my bad

You're telling me the ex1200 is already overkill for a 240l tank, so adding another one would indeed be excessive. I mean, what's the point of having that much filtration power in a relatively small tank? If you're experiencing some sort of water quality issue, throwing more filters at the problem ...