How to dose these plant thingy chemicals stuff

[Thomas Barr <tcbiii at earthlink_net>]

Folks seem to ask many of the same questions every few months in waves.
So for dosing and why:

http://www.aquatic-plants.org/fert/est_index/est_index1.html

This method side steps testing except for CO2 determinations.

You do water changes to make sure nothing gets built up too much and add
enough nutrients to nothing runs out. This way you maintain a good even
stable level of nutrients.

Water changes are easy and part of the basic maintenance and can be used to
your advantage.

Regards, 
Tom Barr