is this the BEST filter setup possible for 50-75g tank?

You are way overkill in any of the 2 configurations.

Having more filtering is good, but this excess will only harm your wallet.

For a 50-75 gallon tank, a single 300+ gph canister filter will do an excellent work. I run my planted 50 gallont with a Penplax Cascade 1000 (350gph) and it's doing an impressive job there.

If what you want if filtration backup (not relying in 1 only filter), get two smaller canisters or two large HOB filters.

I've read UV sterilizers can be harmful if not set properly. If the flow rate is higher than specified, it may contribute to bacteria proliferation (sp¿?). Not sure about this. I just read it in a discussion forum somewhere else. I just read thei nfo on your links about UV and it says "At the correct flow rates, they kill over 99% of waterborne, disease-causing microorganisms in the water", so this seems to be correct.

Of course, if you want to set up your filtration system with those devices, ity should work great, but IMHO it's not needed. Water changes and good fishkeeping habits should keep your tank disease free with and ordinary filter.

To obtain the result, get the recommended size tank for each filter and add it up. This will give your the "standard" combined capacity of the whole filter set up.

Most people say ehiem is the best filter but pricey.

Tank size is just one important parameter in choosing the best filter option. What kind of tank do you plan on?

Fish: species, number, etc.
Planted vs. non-planted.
Substrate type
Frequency of PWC and cleaning you intend to do.

As stated previously, your references to 2-3 Emperor 400's on a 50-75 gal. tank are way over the top. For example, I run a single Emperor 400 on a planted 55 gal. community tank. I do a 20-30% PWC change every week with glass cleaning. The substrate is a 2" base of Shultz's aquatic soil topped with Estes river gravel. My tank is very clean and the plants/fish are thriving. Would adding one or two additional Emperors to mt set up significantly improve the quality of my tank environment....not likely. The kicker is that I would have the pleasure of cleaning and additional 4-8 filter cartidges every week.

Here are 2 links of some filters I prefer. The filter depnds on fish size and population such as if you have oscars, then I would get a canaster filter and I would use a power filter for a smaller fish and smaller population.

http://www.petsmart.com/global/prod...<>ast_id=2534374302023693&bmUID=1137900549652

http://www.petsmart.com/global/prod...<>ast_id=2534374302023693&bmUID=1137900549891

I have 2 Emperor 400's and one Emperor 280 on my 75 gallon which houses 1 adult Oscar, a 5" firemouth, a 5" Jack Dempsey, a bristlenost plecostamus, and 8 giant danios.

By far, this is my cleanest and easiest to manage aquarium. I have never had any water quality issues, algae problems, etc etc. I do a simple 50% water change each week and this aquarium looks perfect all the time.