Nick I dont see why things couldnt just be scaled down for any size tank. Some of the stuff I have is a little pricy but cheaper alturnatives are available. On the waterflow its all about the concept and not so much about the means. You want to remove the detritus /food and waste prior to it having to break down, if and when you do this you dont have to worry so much about nitrification/denitrification and a whole lots of other things, you simple remove it prior to it becoming a problem, this well help you in simplifing things and not having the need to have so many checks in your system (remember the house of cards, hehe).
My skimmer is big because it needs to process a lot of water, if you dont have as much water to process then just scale it down to your tank, but keep in mind that the skimmer is a very important part of your exportation, so make it a good one. The same would apply to a uv. its is not an absolutly needed item, but just one more thing to help you achieve the ultimate goal = great nutrient free water quality.
On the Ozone, to be honest the stuff scares the heck out of me. I do know alot of folks that use it very sucessfully and for alot of years. the use of Ozone is what we call active filtration (skimming would be passive) basically you are releasing a nasty little tazmanian molecule that goes out and activly seeks out stuff to kill, and it really will kill anything it comes in contact with (living or dead) so it can be used but I would suggest many controls be put in place to keep it honest.
Maybe Alberto could shed a little more light on it for us.
Michelle I know you love making me work, but I tell you after the 537 emails from the TOTM thing my one finger typing is getting real quick, lol
Ok on the top off. I have my ro/di unit plumbed right into the tank via a kent float valve. But not much actually goes in. I dose about 7 to 10 gallons a day of kalk so the majority of the toppoff is supplied that way.
Mike