I wouldn't bother with mangroves,I would use chaeto you would need loads of mangroves to do anything.The bio balls section will be submersed,this wont work,they need to be above the water level but I wouldn't use them anyway.
I would also loose the filter at the bottom of the right hand section and use a filter sock instead.
the return pump section in the middle is the section which the water level will drop due to evaporation and will cause bubbles from the water falling from the fuge section.
I would personally have 2 baffles,one each side of the return pump.I would have the flow from both sides going over the first baffle and under the second,this will help eliminate the waterfall effect and reducing the air bubbles.
Hopes this helps
Old Chinese proverb:
Don't go to bed with ichy bum
wake up with smelly finger!!