Does plant take up phosphate as fast as nitrate?

[MikeKoh]

Does plant take up phosphate as fast as nitrate? And what about potassium?

[Plantbrain]

Aquatic plants take up P to N at the ratio of about 10 N's for each P, so 10x as fast uptake of N(Either NH4 or NO3 forms or both).

K+ is harder to measure but we can estimate it fairly closely.
See Epstein 1972's analysis.

Generally, I add about 10X as much KNO3 as KH2PO4.
I over dose K+ and PO4 to some degree.

As long as thwere's enough of each nutrient, it really is a non issue what the ratio is at any given moment, the lebvels change through time and it's extremely unpractical to attempt to maintain and constand level, and more importantly, it's just not needed for any reason I can think of for a nice planted tank(Eg Amano's etc).

Regards,
Tom Barr