EI relies more on water changes and estimating the ppm levels of nutrients: simple, not test kits needed.
PPS relies more on test kits/calibration of said test kits, generally fewwer water changes.
But both methods can use more or less water changes and both methods can use less more testing.
For new folks or folks with many tanks, EI is far simpler and effective when trying to solve algae or plant health problems.
I do EI and don't change the water on some tanks for 2-3 or more weeks.
If water changes are really and issue and if you really want to balance the tank, go non CO2.
No test kits and no testing and no water changes.
That is, if you really want to "balance" a tank.
I do all three but don't need the test kits unless I have a specific question that needs answered.
Why do all that testing and expense for a maintenance routine? It's a lot of work and it's more complicated to explain to new folks.
I'm not sure what is "new" about testing and adding nutrients as they are used up.
That's something I still don't understand nor have recieved and straight answer ever from anyone to date.
Regards,
Tom Barr
www.BarrReport.com