It looks like you have brown algae and green spot algae. Brown algae likes lower light and silica (plastic). You will see this on your plastic ornaments, your corners and in darker areas. They are more common in new tanks, and seem go grow better in areas with less water flow.

I would try to keep your nitrates between 10-20ppm. Do weekly water changes, this adds nutrients and removes wastes.

How are your barbs with that angel? Most are tail nippers.

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--->Pictures of my 75g Amazon tank<----