Salinity 1.025
Ammonia 0
nitrite 0
ph 8.2
nitrate (barely register able...but lets call it .1)
phosphate 0
I dont have a skimmer.
I have a 125DT/55sump, a foam wall background(probably the most significant filtration), 12x19 scrubber station, 100lbs of LR and GFO/Carbon reactor.
The only water change is when I have evaporation and need to top off, about 3-5g per week. This will be changing soon, since I want to improve the clarity of the rocks and the debris that is collecting.
I have a med-heavy bio load(depends on whos assessing it).
My point....consider a scrubber,a cheap reactor, and maybe a foam wall build, to help reduce your undesirable params.
Dont get me wrong, skimmers and LR for filtration are great. In fact, I'm shopping for a skimmer right now, since I believe it will improve my clarity on my rocks. They have a tiny peach fuzz grime buildup, and I relate this directly to not having a skimmer. But since your concerned about water quality...check into the other things I mentioned.
Hope this help.