I have a 55g with a 1375GPH pump + return pump on medium-high. I have heavy amounts of live rock in my tank that break up the flow too, so there are probably some dead spots
I never include returns in turnover rate but you are running 25 times turn over IF that pump is always at that GPH. I personally would run less calcium carbonate in your dose if you are needing to blow if off of rocks.
To give you an idea I run about 28000 GPH in just powerhead flow in my 300, i’m 99% SPS though and run a much heavier dose of calcium carbonate mixed with a bit of coral food and nothing settles.