Help with aerating res

I've got 70L (18gal) res, and only one 200L/H pump circulating the water. Water doesn't move alot on the surface, but a little bit. Is this enough to keep it fresh? It will get more aerated when given to plants as drip feed, but I want to keep the res fresh.

It’s fine. It only has to move water from bottom to top to keep it aerated. The most effective oxygen absorption takes place at the surface.