Yes Raul,
Adding PO4, more NO3, K, traces, CO2 are needed when you add more light.
The __loading rate__ is what is important.
How fast are these being used up. When the plant needs are low, there's going to be a lot more play.
This was one reason I played around with high light tanks long before many did. With faster growing, high light systems, you are forced to be more critical about CO2, NO3 etc.
But you also discover the rates of uptake of PO4, NO3, and what are the optimal CO2 saturation points(30ppm is what has been found in the research FYI).
Now if take these same parameters and apply them to low light CO2 tank, the results are nothing less than stunning and easy to control.
By driving the light higher, we have be able to go back and fully optimize the lower light tanks also.
Without high light, we would have never found out these more optimal ranges.
With water changes, 50% water changes will level off any over dosing provided the levels in the tap are constant/low etc.
The levels start approaching asymtotically to a maximum level but it is a log curve, not linear, eg the levels don't continue to increase.
Anyway, do a large water change if you are worried.
Most folks that problems with plants generally have something limiting growth, not an excess.
The other good thing about large water changes, removes the Dissolved organic PO4 and NO3/NH4 forms which select for various algae and that plants will not be able to use.
Plants prefer the inorganic labile forms, so doing large frequent water changes and dosing afterwards will provide the lower algae growth with excellent plant growth.
It also makes testing for NO3/PO4 etc easier(all inorganic forms) and many don't test at all since they can eastimate their NO3/PO4 etc just fine using that method.
Regards,
Tom Barr