[defdac]

You dose 5 ppm NO3 (and *everything else*, KH2PO4, Micros, GH) after wc and keep up with CO2.

You don't dose the next fulldoseofeverything until the pearling from plants are noticable less, not nil, just less.

Then you can be totally sure the plants need everything again and nothing is building up. If some nutrient should be building up anyway, however very unlikely, the large wc will keep it down.

 

[defdac]

It do work.

Up the KH2PO4-dose and you will rock bottom your NO3-levels in notime - if the CO2-levels are good.

You will probably now say something like "But my PO4-test says 2 ppm already!".

My response will be: That is probably DOP, not DIP. Add DIP in the form of KH2PO4 that the plants can utilize instead of DOP that can't be used until it is mineralized in the substrate (which takes a lot more time than the growth rate)

And you measured NO3 is probably DON. Add som DIN in the form of KNO3 and it will probably be taken up faster. In fact adding KNO3 despite high NO3-readings will probably plummet your NO3-levels. Try it.

 

[defdac]

it could be anything. And if po4 is @ 1.5ppm and you thought it's 0 and you add 1.5 ppm? then you have 3 ppm....

See my edited post.

You have to know if you measured organic bound PO4 or inorganic. Plants doesn't use organic bound PO4 (fish poo) until it is mineralized in the substrate. KH2PO4 is inorganic and can be utilized directly by the plants.

When they get a lot of inorganic PO4 the NO3-levels dive. I promise you. If you're on target with CO2 that is.