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Re: Bacteria, algae, and N:P

Tom Barr wrote:

> Also, I found compelling evidence for not letting your N:P ratio fall below
> 16:1 for aquatic plants. Neat stuff. So if you have a NO3 of 5ppm your P
> would/should not fall below 0.3ppm or so. The optimum seemed to be about
> 10:1 or so of the studies I looked at. So .5ppm for a NO3 of 5ppm. This
> might explain why at 1.2 ppm of P and my higher NO3(10-15ppm or so) that my
> plants did well. Steve Dixon did this lower NO3 at 2-5ppm with a pulse of P
> to about .2ppm or so. He had good results and so did I. We both had a
> similarly close ratio. I have been doing to the lower end ratios these
> days(pulses of P with lower NO3 2-5ppm or so) I want to find out how far
> this ratio can go. What is the upper limit with a set of CO2 levels/light
> values and excess Fe, K+ and trace elements without algae build up?

This is very interesting!

I have recently begun additions of K2HPO4 (lab grade). I mixed 6 grams in
300ml and have been adding 5ml to my 55 gal tank daily. I have measured the
tank PO4 immediately after additions and found the PO4 levels to rise to .4
ppm.  Without additional PO4, they had been at .1ppm.

My nitrate level is about 5ppm after addition of NO3 (KNO3). I had been
adding NO3 daily for quite awhile.

I did not know what to expect, but I feared an algae bloom. I tried this
after Tom Barr's comments in previous postings on phosphate additions. After
about a week of this my tank shows no signs of algae. But the stem plants
and Java fern are definitely responding.

Very interesting, given the long standing view on this digest that PO4
should be driven down to lowest levels possible.

Augustine Rodriguez
Rice Lake, WI USA