Keg to High-End Aquarium

As I have alluded to, the goal is to convert an 11 gallon (50 liter) keg into a high-end aquarium.

The goal is:

Window to see inside, access panel and room for emerged plant growth. Zero visible or internal cabling, filters, heaters. High power led light with dim in/out arduino timer. Co2 injection managed by arduino. Undergravel filter & drain.

Here is where we start:

Stop judging my room. This stage is after the spear removal, which was quite complicated to work around. In the end I used a long, thick bolt with an oversized washer and bolt. This was to push the central spire down while unscrewing the spear.

Not a clean job but here I have removed the viewing window (I may have sourced a supplier for the bespoke curved Low Iron glass front). I also removed the access panels for the top and hope to use the center hole to house the high power LED light. Several pilot holes have been drilled to mark the locations for; LED light cabling (potentially water cooling), undergravel drainage/air filter (center bottom) and the piping for this.

I am still thinking how to inject the co2, this will most likely be from under the undergravel air filter.

My next stage sanding down the keg, evening out welds and progressing through grits until there is a consistent finish. Ultimately I will be getting the interior to a mirror like quality and applying a light coat of clear epoxy as stainless steel corrodes extremely slowly.

While working on this I am also ordering the parts to have an arduino controlled lighting, co2 injection, air bubbler and temperature control. I need quite a bit of help with this aspect and any suggestions would be appreciated, especially for anyone willing to help with the circuitry as I would like to reduce down to 1 UK plug if possible.