Not that familiar with the TL450 however, with most skimmers there is a valve for letting the air in, do you have anything like that. For my RSM130 we do, this way you can adjust how much skimming you want done.
Interms of NO3, what levels are we talking? Also, I'd like to mention the strip test kits are very reliable. Ideally use Salifert's or API.
It's worth bearing in mind that you'll get very little skimate out of a brand new setup in the early days, so don't pull your hair out if you're not getting much performance out of your skimmer.
Make sure it's positioned correctly so that any bubbles produced are coming roughly half way up the collection cup neck.
See how you go in the short term, mid to long term you will probably want to replace the stock skimmer as to be honest it's quite poor.
I'd suggest buying a better water quality test kit, the 5 in 1 test strips are notoriously inaccurate and marine keeping is all about the detail. Salifert test kits for each individual compound are a good investment (start off with NH4, NO2, NO3, PO4, pH, further down the line you'll want to invest in some additional test kits which cover KH and Ca, Mg etc it you're thinking about keeping corals).