actually I did consider the dead zone in the cave, so I made it such that the water being sucked into the lower chamber. I put sinking food in that area to see if it will trap detritus and it didn't, so im not sure it will still be a problem...
And the area where the rocks are near the wall is accessible by an algae scraper so im fine with cleaning it.
I haven't gotten my wave maker yet if you haven't noticed, so im unsure if the water dynamics would change later. Thanks for the advice though!