[cS]

I don't see a lot of discussion about the use of specific ratios for the different growth stages of aquatic plants. This is a major premise in ADA's Green Brighty series but they are the only ones that use it.

Are we not already doing this, even though we don't explicitly say so? The way that I see it: with the exception for those who follow the Estimative Index to the letter, we all adjust our nutrients (N, P, K, and to some extent micronutrients & C) according to plant growth...ESPECIALLY those who are testkit users. In the early stages of a tank or after major prunings, less nutrients are dosed to maintain X ppm while more is needed to maintain the same concentration as plant mass increases. Even those who don't partake in testkits dose accordingly. Estimative Index users are the only exceptions in that they dose a fixed concentration weekly regardless of plant mass/etc. and flush the left overs at the week's end.

I take "ratio" to mean an approach to dosing as to avoid "waste of nutrients"; and in the cases of "just-enough" dosers (I'll ignore Edward's PPS here because I'm still trying to understand the system. ), to prolong the period between water changes. Within a certain range (and it is broad as HeyPK noted and the Estimative Index suggests), plants do not really care what ratio of nutrients are in the water column/substrate, as long as there are some for them to uptake. Up to some maximum, the rate of uptake increases as the [X] increases, assuming maximum light of course. Toxicity is a complex issue that I rather not approach at this moment. Speaking of which, what are some of the known/suspected toxicities in the hobby...beside potassium?

So I don't really understand the difference between ADA and US fertilization methods in this respect.

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One thing I am confused over is the 10:1:10 NPK ratio. Does this mean that for every mol N taken up, one mol of P and one mol of K are taken up as well? Or does this ratio only apply to healthy established plants? What about a K-deficient plant that is being placed in a K-rich environment? Would it temporarily take up more K than N and P? If so, then that may explain the rationale behind ADA's reccomendation of more K during the early stages, as the plants uses up more K to produce the roots relative to N and P.

I am very surprised that no one has taken ADA products to a lab for analysis.

I am very surprised that after all these years and discussions, no one has taken Flourish Excel to the lab. There has to be professional chemists among our ranks no? :mrgreen: