The 29 biocube was my first aquarium when I was a sophomore in college, and being a college kid I tend to mess with and tweak everything. I no longer have the aquarium so no pics sorry but I can explain things.
Before I filled it up
I modified the lights to run 4 t5's
I then got a bigger return pump. I sealed the hole for the return, added a 90 elbow and ran a pipe left the entire length of the back. Then sealed that pipe to the back wall and drilled lots of small holes in the back wall and pipe creating a spray bar, where only the holes could be seen, not the pipe.
With the extra flow I had to take a dremel and widen the intake holes on the right side, and the holes on the basket that sits above the center chamber.
Switched out all the bio balls to live rubble.and added some chaeto in center chamber. Used two 3 bulb true lumen led's that I sealed with clear coat attached to the bottom of the basket to grow chaeto.
Ended up adding a biocube UV sterilizer to the return pump, before it hits the elbow and goes to the spray bar.
I used that mod for about six months before I decided to switch that tank to all sps corals and wanted a real refugium.
I moved all my lps to my 50 and my fish to a holding tank
Drained the tank and on the back of the aquarium I sealed an acrylic box to the back measuring the entire length and width of the tank, and 3 inches deep.
I added a baffle near the end with a small return pump plumbed directly into the spray bar adding more flow to the display.
Drilled some holes in the back right side of the tank to let water pass through the now built in refugium.
With a 4 inch sand bed, lots of macro algae, rubble, some shrimp and nassarius snails and a refugium light.
I added a tunze skimmer to the right chamber, with a modified collection cup to fit in the biocube hood.
This made me move my 3 gallon heater to the left chamber with the return pump so I had to keep my water level above the maximum water line.
After running water in it for 3 days I realzied with the return pumps, skimmer, and lights I needed a chiller.
I replaced the cooling fans in the hood for the lights, to two bigger ones, along with cutting bigger holes in the top of the hood to allow more air flow.
I then cut square holes along the back side of the hood to allow more flow to hid the filter and skimmer.
Along with adding two cooling fans to the refugium and refugium light.
Picked up a fluval 205 canister cheap and decided to have fun
Drilled a rectangular hole in the back top of my cabinet, and cut a slit in the cabinet so the tubes will fit.
Drilled a hole in the right side back panel of the aquarium in the bottom below the plastic grate and my tunze skimmer
added a bulk head allowing me to run the drain tube directly into the filter so I dont have to see any tubes.
Drilled an identical hole on the left side but near the middle for the return
The tube traveled horizontal right above the return pump for the main built in filter, then went in to the central chamber.
I removed the bottom plastic grate of the middle chamber, allowing me to put the live rock and chaeto lower in that chamber.
I then added a 3/4" squid to the canister filter in the middle chamber which was under water. With the two returns entering the display where the original biocube return was that I sealed, and another the same height directly to the left of the inlet holes of the built in filter.
System Over View
Upgraded lights
upgraded built in filter
built in/extended refugium
Canister filter
3 gallon heater