You dont need to change, just tone down the speed, like i said i've got a maxspec and it runs 60% at max on random setting and the tanks larger than yours.I thought about changing the gyre into two "MP10 Ecotech" units.
And i did wash the sand for 30 minutes. Thought that would be enough.
The fact i can see bare bottom on the other side of your tank suggests either the sands to fine or your flows to fast.