Hey BigJoe....if your tank's been cycling since the 8th, it's not done cycling. Your parameters will go up and down during your cycling. I would give it at least 6 to 8 weeks. The Penguin filters should be fine now, but I would suggest getting a canister filter, specially if you're going to be running carbon, it's much much cheaper to use media bags and buy carbon by the bucket/bottle. As for the Koralia, it should be fine, but you'll need more than one, remember that you have to take care of those "dead spots" so debris, fish waste, etc etc can be pushed up and picked up by your filter.
As for using tap water...it all depends...have you ever tested your water for total dissolved solids? a TDS meter? that should tell you a lot. In my case, I also used tap water, only to have a horrible case of "green water" a month after my tank cycled. I had to buy a UV sterelizer and I've been running it since.
Once your tank has cycled, you don't need to make such a big water change...10-15 percent should be enough. You don't want to take everything out of balance in such a new tank.
I don't have a sump or refuge and I'm doin' fine.
You can pm me anytime, I went through all of this recently and I could tell you how to save some cash so you don't go buying stuff you won't need. I know where you're coming from, I had a fresh water tank too and I thought a lot of the steps used/applied into a FW tank would easily migrate to SW tanks...a big no no.
Ah, don't forget about lighting....you need different lights for SW tanks.
Anyway, I hope this helps.
Patience is the key. Don't rush and you'll be fine. | 
