I have red algae all over my 2 month old 72 gal. freshwater tank ,
especially on the plants . Looks like red dust . I've tried a sheet to cover
the tank , but I'm not sure if it's having any positive affect .

I think this might be "brown algae" -- diatoms. It's common in newly set up
tanks, and may go away on its own.

Or get yourself some otocinclus catfish. They are very small, and are at their
best in groups, so get several. One for each ten gallons of tank volume.
They'll make short work of brown algae.

Leigh

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