I just finished installing my new sump. After 30 min. of tweaking the flow rate from my pump to the main tank, my wife and kids asked what's the purpose of this extra tank. after steping back and looking at it I could not give them a good answer. I started out with a 55 gal tank with two 280 Emperor filters, Super Skimmer by Coralife, 200 watt heater, three Koralia power heads in the tank. Now I have a sump with 20 lbs. of live sand a skimmer, heater and Quietone 3000 pump and three power heads in the tank. So what was the point of all this work (I hard plumb my overflow box and return pump)?

You did nothing, if I were you I'd change back everything.. Just kidding. Sumps has so many functions. First and the best is that you add some extra water to your existing system. More water, more oxygen, more trace elements, healthier and happier livestock. You also installed an overflow box in the main tank, which drains the water to the sump. This overflow box will give you a perfect surface skimming and agitation ( faster gas exchange, more oxygen), You'll never have to deal with films on the top of your water again .

Sumps are also great for hiding equipments, such as heater or a protein skimmer. Later on you can easily switch the whiole sump to a refugium.

You'll never have to deal with water evaporation in your main tank again ( more stabilized salinity and temperature), you just have to top off the sump, that's all.
Water changes will be easier. Instead of plug in and out the Emperors, you just have to turn of the pump in your sump, and stop the overflow.
You don't have to clean the sump nearly as much as a HOB powerfilter.

Sumps are great. I hope this answer satisfied you, and your wife as well:-)

Yea fuges help alot and you can also hook up a UV sterilizer if you wanted to. The extra water really does help and makes it a more stable system. Another idea is you can grow and house shrimp in the fuge for fish food. Wish i had a big enough tank for a sump...

you should use a micron bag to catch the detritus and bubbles

Actually Sg is perfect at 1.026. Are you using a refractometer or a swing arm hydrometer?

You might to have it checked against a calibrated refractometer at your LFS. My deep six hydro was .004 off when I had it checked. I went ahead and got a refractometer.