You have two questions it seems like to me... the below is MHO and not a general consensus.
1st not performing water change and having a successful reef tank, sounds like either balling method or triton method noted below.
Exactly what is so difficult in producing equivalent water, similar to seawater, for a reef aquarium? Low phosphate and nitrate values are not decisive factors in the quality of aquarium water. A perfect magnesium or calcium content perhaps? Far from it – the challenge lies in imitating the parameters that prevail in the ocean to the greatest extent possible and keeping them at a constant level. One often finds aquaria with values that are significantly different than seawater, but nevertheless contain beautiful coral, due to the constancy factor alone. In this case, the coral has adapted to prevailing conditions; an animal environment that approximates the natural habitat, however, cannot be said to exist. Which water treatment methods were used in the past? Until now, weekly water changes have been required in order to add all materials to the water considered necessary for optimum coral maintenance and to eliminate any excessive doses. This approach quickly encountered limitations, since it failed to work especially in cases of high coral density. So devices such as calcium reactors were added or the balling method was used for basic supply of the major consumable elements – calcium, magnesium and bicarbonate. Since in these cases, however, the necessary trace elements and amino acids were missing, they were added according to the size of the aquarium. Why are the previous methods risky? Every aquarium is different in terms of the number and composition of animals. This is also true with respect to the need and consumption of materials found in the water. So it is not as simple as creating a standard mixture of elements deemed necessary purely on the basis of the liter capacity of the aquarium. The previous methods enumerated calculate possible excessive dosage from the start; the water changes are an attempt to restore balance. A high risk, that is not only complicated and tedious, but very prone to error. Excessive dosage residue remains despite water changes and results in fluctuating water values – a serious stress factor and danger for the animals. Exactly what is different about the TRITON method? The TRITON method takes a completely different approach. TRITON imitates the quality that best approximates saltwater and keeps it constant over the long term without the need for water changes.
the 2nd and more challenging is the relationship between doing water changes and a good skimmer.
It's good to have one to help remove dissolved organics for the times between water changes, however this is limited by trapped and decomposing organics in the nooks and crannies of both your substrate (if you have one) and rock. I have an external 3000ext (on the 390 gallon system) and up till recently was unimpressed, that's when I decided to increase the pump size feeding the skimmer and now I can't keep up with the foam it's making. Not stating that's what's going on with your system, just my personal observation. I don't have NO3 issue or PO4 issues, in fact they're IMHO too low to support organisms that require trace amount of either and is why I started dosing KNO3, still on the fence about additives for PO4.
I don't do water changes on my 170gallon system but, I do add trace elements via fauna marin Balling Light and have seen better growth since I starting, before that water changes did nothing to help my tank out but did wonders for growing GHA issue (gone over the course of a few months after I stop doing WC), assuming (as I have no proof) I was removing/killing good bacteria as my WC parameters might have not been matched 100% exactly.
In fact I'll post up another question... with the investment manufactures have made to improvements in new skimmer design and pumps on the market today, could they be pulling out too much? Like you noted "I looked up reeflife skimmers and heard good reviews on them" this is IMO a less efficient spray injection skimmer by today's standard but they work well and everyone that has one has nothing but high praise for them. Why is that, could it be that they're leaving behind just enough organics to be helpful?
Not to add even more confusion but, methods like zeovit also "recommends" not using pin-wheel type skimmers as they pull too much organics out of the water column.
I'm theorizing as I have no conclusive proof, standard WC in the area of 15%-25% destabilize our systems removing both good and bad, smaller WC are better and replace needed trace elements but, with the invent of systems like Fauna Marin Balling Light and TRITON might no longer be needed or required. They flipside to that is you need to really understand what's in your tank or it can go south on you quickly.
