Hi folks, I've got a 6x2x2 with a 5 ft sump. It was a full blown reef tank until about two years ago when I decommissioned it. I've just refilled it and I'm going to set it up as a discus tank with a few compatible fish. I would like to run through my plan with those in the know so that you might identify mistakes that I'm about to make.

My filter is a 100 micron sock, below this is a MBBR filter with approximately 20 litres of K1 filter media. After that there is about 30 Litres of submerged bio balls. The water then returns to the tank via a variable speed DC pump.

The proposed stock list is as follows, not set in stone though.

12 Discus, purchased at 3-4 inches.
50 Cardinal tetras
10 Sterbai cory's
6 Blue ram's
10 -15 marbled hatchets
2-3 Bristlenose catfish
Agassizi's - mabye one boy and a few girls.

Is this overstocked, will the filtration handle it, are the fishies compatible?

My planned aquascape will be a mix of driftwood and rocks on a bare bottom (painted blue). I'm thinking something minimalist. My lighting is a cheap RGB LED strip, I'm planning on running it very dim. Once the discus have grown I might consider putting in a spotlight and a planted section. No plants for now though.

For water changes I'm planning on converting my 4 stage RO filter to a 4 carbon cartridge inline dechlorinator. I'm going to hard line it to my tank and do very slow continuous water changes, my tank has a permanent overflow drain to outside. I can turn on the tap slowly and walk away. So the plan is to slowly push tap water through 4 carbon filter cartridges and then straight into the tank. Do you think this will work? MY tap water is awesome, <50ppm dissolved solids and 25 degrees celcius but a fair wack of chlorine at times.

What do you folks think? What have I missed?

Thanks all.