Growth inhibitor Options

[CP]

One of my idealistic aim when I started off this hobby is to design a system so perfect that water changes are eliminated or minimised.To date,it remains well......idealistic.

For bio tanks,we all know that the end product is nitrates.And nitrates above 50ppm is harmful over the long term and stunts the fish.Whereas there are many products in the market that reduces (or is it CLAIMS to reduce),does it mean that our problem is solved if we manage to get rid of nitrate?

I used to think that solving the nitrates issue means EUREKA!!!Till I came to know about this "growth inhibitor" issue.I have read about it somewhere in the website before but had never seriously give it a thought till recently when a fellow forumer (bro Goldrush) mentioned it in one of his topics.

The fact (or is it theory) is that fishes will continue to secrete "growth inhibitors"
to prevent themselves from growing in a cramped environment(our fish tanks),to boost their chances of survival.This occurs naturally,much like when DO is low (eg when you off the air pump),the fishes will lie low and become less active knowing that oxygen supply is limited.

So what does it tell us?It means that we still have to perform water changes to get rid of the growth inhibitors if we want our fishes to grow,irrespective of whether nitatres,nitrites,ammonia and whatsoever has been eliminated.
Unless,of course,there is this thing in the market called "growth inhibitor remover-add 5ml per 100l of water weekly".

Was wondering if growth inhibitors can be measured.Eg,if nitrates to be kept at less than 50ppm,growth inhibitors shd br kept at xppm.Best of all,if it can be eliminated.