While I readily admit I am no expert, my phosphates and nitrates are consistently very low despite being somewhat lazy with water changes, so I'll toss in my two cents.
I allow the back wall of my tank to remain covered in algae. It gives my pincushion urchin and foxface a large grazing surface, and acts like a super inefficient algae turf scrubber. I also have a refugium with DSB, Halimeda, Halymenia, Gracilliara, and Chaetomorpha. In my DT, I also have a Tridacna Derasa clam. All of these decrease Nitrates (though for some the change is somewhat negligible, I find the combined effect impressive), and all the Macros decrease phosphates as well.
While I appreciate the various technological solutions available to us, I always try to find natural solutions.
To give you an idea, I haven't actually done a water change in over a month (baaaaaaad John). I have a neon goby, clownfish, six line wrasse, yellowtail damsel, foxface rabbit fish, tons of corals and inverts, and my nitrates are consistently below 5 ppm, phosphates have yet to read over .5 ppm, usually read .25 ppm.
