Luke,
I haven`t been replying because i`m only a nooby myself and thought others with more knowledge than me could have been of better assistance.
However since you have been waiting a while, i will have a go:
All i can say is this is what -> I <- would do:
As we discussed, i think lighting issue can simply be resolved with some quick and easy DIY.
You would need to make better mesurements yourself, so dont hold me to this, but i think you could fit in, 2 X 15inch 14 W tubes just at the back where you have 16" of room! The tubes are 15" and then the end caps from the controller probably less than 1/2 inch either end. I think they will just fit in.
Buy two arcadia 15inch T8 tubes, one of each:
http/www.aquatics-online.co.uk/Z046151.asp
Arcadia 15in. Freshwater Lamp 14w £8.99
Arcadia 15in. Original Tropical Lamp 14w £5.89
Then u need 2 reflectors:
http/www.aquatics-online.co.uk/Z045149.asp
Arcadia 18in. Fluorescent Reflector £4.99 each
(i cant find any 15 inch ones, but these will be fine just cut them down.
The lamp clips are also included with the reflector!!
Just get some with the normal push on lamp connectors: look at this page and look where is says in a yellow box: IP64...u want that connection not Ip67!
I can`t find an arcadia 15W twin controller but i`m sure if u do a bigger search than me! This is the same thing / what you want: VisiLux Twin 18/20w T8 (1in.) Light Unit £19.99 on:
http/www.aquatics-online.co.uk/Z044151.asp BUT i`d go with arcadia if you can find one!!
THATS all the hardware for lighting. Then u just need 4 small nut and bolts from B&Q, and drill your hood in 2 places for each light unit and fix in the reflectors! REALLY SIMPLE! i didnt do a cowboy job with mine, but the hood was so soft, that i used a bradhall to mark where i wanted to drill and ended up pushing my way through with that! I didnt even need to drill. So just put 2 holes in the hood for each reflector and bolt it in. Then use £2.99 black model paint, just a dab on each bolt head so that it matches your hood! But tbh, they don`t look bad chrome/steel.
Once your reflectors are in you just clip in your lights, into the clips in the reflectors (that as i said, are supplied with the reflectors) then put your controller behind the tank or mine is in the cabinet underneath since there is a decent amount of wire!
That updates your lighting situation. The CO2 unit you got looks ok!
NOW AFTER ALL THAT: you have thrown what i think is a spanner in the works...i`ve just read u want a puffer, but dont puffers need brackish water
....i.e crap for plants!!
Hope that helps
Chris
PS> Post away guys if i have said anything wrong!