Excess nutrients


Lifetime Members
Jan 23, 2005
Great job on the first report Tom!

The idea that I've always struggled to understand is that excess nutrients do not cause algae. Maybe I can work on a flash animation that would explain my confusion and help others understand. I was thinking of bar graph's on the left of the animation showing concentrations of micros and macros, and then bar graph's on the right showing algae and SAM's growth rates. We would start with a balanced tank, where the nutrient concentration favors the growth of SAM's rather than algae. Then overdose with say Iron. Plant growth/momentum would increase and some other nutrient would run out. When that nutrient ran out, the plant growth would stall and algae would start to grow. Do I understand this concept correctly? Is this how it works if you overdose any of the Macros or Micros?

Tom Barr

Staff member
Jan 23, 2005
Re: Excess nutrients

If you would like to do that with animation, that would be great.

I think line graphes are more useful. We made a DOS program at UCSB when we did an ecological modeling course. It might be a bit more involoved than you want to do. But it might be useful in modeling a prediction and testing it and seeing how well it matches up to a real tank.

But a bar grapgh like you suggest would be easier. still, I'm much more in favor a well done line graph over time. You can have several different lines on the same graph. One SAM's, algae, phytoplankton, zooplankton/herbivores even, light inoputs, NO3 inputs etc.

Sort of like a dosing calculator but that makes a prediction model based on plant growth with a certain number of innputs and assumptions.

Limitation occurs not from over dosing other nutrients, but rather, relative to the plant's need.

If we do not add anything to the system(A rather enormous assumption) and let it go, then adding an excess of everything else will drive one nutrient down to limiting levels. Then ratios may become more important.

But this is simply never done in aquariums. Reefs with no water changes etc, non CO2 tanks, they all have input and exports.

That changes things and the assumption.

Reefs have skimmers from hell, refugiums, one or both. That's a lot of export.

Pruning large amounts of plants, cleaning filters etc from a non CO2 exports........

I'll have another article that deals with enzymes and energy uptake next month.

But if you allow a nutrient to run out, then yes, you have a stall and then get algae. Thuis does not apply nearly as much to some nutrients as much as others. Plants are fairly tolerant of PO4 limiting conditions but not say, Nitrogen.

Not sure if this answers your question........


Tom Barr