Re: Nutrient Ratios

In my experience, aquatic plants have a natural, intrinsic maximal growth 
rate. This intrinsic growth rate changes over time, even under constant, 
rigorously controlled conditions. The change occurs diurnally of course 
and also cyclically over longer time periods. When you supply nutrients 
to your plants the goal is to support this intrinsic growth rate, not to 
supply nutrients at some optimal ratio to one another. Aquatic plants 
have a great capacity to absorb and store mineral nutrients so as long as 
they are supplied in excess, the ratio of one nutrient to another is not 
critical (in terms of mineral nutrition). The rate of supply is the 
critical factor and will, of course, be different for each situation. 
Many studies exist in which a single nutrient was supplied at different 
rates and the resultant growth and tissue content was measured. For 
aquatic plants these types of experiments were popular in the 30's and 
40's, though I have spent about 4 years or research doing similar work 
... I think Paul K. has also spent some time on these types of experiments.

Dr. dave.