OK, I need some help with sump design or use of my current design

[Nocturnal]

Here's the problem. I have a lot of Nitrates. I have a FOWLR and I feed heavily so I need to combat this better than just water changes alone.
Tank is a 125 with ~130+ lbs of live rock. The sump is a "converted" amiracle wet/dry (the dual chamber one to the right in this picture)

Where the bioballs used to be I have two socks that filter the water. These are changed twice a week. The water then goes to the end and there are two holes drilled. One is the return pump to the tank the other is the pump that feeds my MRC-2 skimmer run externally dumping back into the "sump"
Both of these are MAK4s. Plus I have another pump that is on a closed loop (~1200gph)

Under the stand I have no room to add anything. I can NOT remove the sump either unless I cut it apart. The only way to get it out is to take the tank off and remove the sump from the top of the stand. Not going to happen. I can either utilize this sump or cut it apart and stick something else in it's place. I would LOVE to run a large RDSB, but like I said, I can't add anything under the tank without removing the sump and under the tank is the only place I have to put equipment.

How can I transform this set up into a more efficient way to get rid of nitrates?? Any ideas??

 

[NeO]

Sure you can do something with your exist sump.
You can close off the opening that "goes to the end" with some acrylic and weldon and drill a hole up high on that same wall that you are closing the opening so the water can flow to "the end", add sand and some algae and you are good to go.

Does that make sense to you?

Gustavo

 

[Nocturnal]

Absolutely makes sense to me. Thank you Gustavo!!! I actually thought of something like this right after I posted. I just hope it flows enough.

Amazing no one else had an idea

Thanks again