I've been following along on your build and 2 things; 1.) It is coming along very well and looks great! 2.) I am jealous!
Based on everything you've done up until now, I'm fairly sure you've done the research on those baffles but just want to make sure they're pure plastic/pvc and you double checked with the manufacturer about using them safely in saltwater. It would really suck to get everything set up, running and then find out they're leaching something into your water.
Once again, great build and looking forward to your next steps and final product!