I honestly can not explain the enduring nature of a premise which is so obviously counterintuitive. Let's look at it from yet another perspective. Let's say I have a 200 gallon tank and the nitrate concentration is 80 ppm (mg/liter). Let's say that I remove 100 gallons. So, I'm left with 100 gallons (380 liters) at 80 mg/liter.
80 mg/liter x 380 liter = 30,400 mg of nitrate.
If I now add back the missing 100 gallons, I now have:
30,400 mg nitrate
760 liters
= 40 mg/liter (ppm)
So, a 50% wc has reduced the nitrate concentration by 50%...as anticipated.
Every water change is a snapshot isolated in time from any performed previously. You are dealing ONLY with the nitrate concentration at that specific moment in time. The wc regimen that you adopt is designed to maintain nitrates within a certain tolerable RANGE over that period of time between wcs. Within that period of time, the nitrates are, of course, increasing from one minute to the next.[/QU
Any intelligent person understands these facts and this is exactly why water changes are important. Why do people waste more effort trying to avoid needed maintenance rather than getting it done? People should not keep living things if they are too lazy to take excellent care of them. I say this after seeing so many idiots who have oscars with HLLE who think a WC once every month or two is sufficient. Snapshots that maintain pollution to a minimum are far better than the bare minimum.