That's why I reccomend the rtv silicone. It works well on acrylic where as the overly expensive Aqueon stuff doesn't.

I hope you're planning on replacing the baffles with glass.
I'd suggest 1/4".
I'd also suggest waiting at least 72 hours after installing them before you put water back in, and use a fan to blow room air through your stand to 'air out' the silicone fumes. This will help speed up the curing time. The silicone needs to interact with the surrounding air to cure.

If you're going to go with 1/4" plexi again, look for some rubber strips that wrap the edges of the plex. These are similar to what window glass installers use and you can use them to 'pressure fit' the plex into place.
This product is a 'channel' that wraps the edge of the plex with flat outer edges.
Just do some research on it being 'potable', but I've seen threads where it's been used long-term successfully.

This is kinda what I had in mind if you use plex again

Thanks everyone!

At this time I've decided to stuff the area where water splashes to reduce the noise.

I gonna take my time and research some options before moving on, the tank will be fine, it's onlyour noisy which probably doesn't bother anyone inside the tank lol.

It looks I'll be draining my sump, so I may as well look into ways of improving my current setup.

That being said any sump ideas or design tips would be appreciated.

Can you post a picture of your current setup?