I have not witnessed any change in my fish or corals since the temp change other then no ich. I have very good water flow across the surface of my tank. In fact my flow hits the opposite corner and is driven towards the DSB
so hard that it has caused a low spot in the sand. I am running about 500 GPH
and am thinking about putting a TEE at the end of the return to reduce divert some of the flow to another direction.
One thing I would say to support the surface flow theory is good trout water.... LOL. I don't know how many of you are fly fisherman but we always look for a good ripple in the surface to find trout. A very wide slow flowing river does not have the O2
that trout like. The Colorado river is great trout fishing in the narrow high flow areas that also contain deep lower flow pools. In the wide slow flowing ares their are very few trout but more carp and suckers.