Re: of nitrogen and phosphorous

>     * Subject: Of Phosphates and Nitrates 
>     * From: Calvin Chin <cfc at pacific_net.sg> 

..with snips...                                      

>Few questions:
>1. Nitrates and phosphates usually go hand in hand inducing heavy algal
>growth. Supposing we manage to get rid of phosphates in the aquarium but
>Nitrates are still present. Will Nitrates alone be sufficient for algae to
>grow? Which is a better nutrient for algal growth? Is it Phosphate, or
>Nitrate, or are both needed?

	It seems that all the algae need phosphate, but that the
	blue-greens (cyanobacteria) can do without nitrate.  See
	Dave's posting.  As numerous people have reported, you can
	have a fair bit of nitrate without algae problems

>3. Supposing the regime as prescribed by Paul and Kevin works, does it mean
>that I can do away with the bi-weekly water changes and just change water
>only when phosphates go out of control?

	I would not do this, and we recommended water changes in our
	article.  The water changes prevent the buildup of things other
	than phosphate - the phosphate is removed in plant material thrown
	out.  The whole point is to use the _plants_ to control phosphate.

>5. Instead of adding Nitrates, will it be just sufficient to increase the
>feeding of my fish (relying on the extra Nitrates produced.) But I also
>understand that phosphates will no doubt, increase. 

	I suspect that, in many cases, the ratio of N/P in fish food
	is low enough that the _nitrogen_ runs short, and the tank has
	too much free phosphate in it after a bit.  The result would
	be algae, and plants that do poorly.

>because Paul and Kevin's theory will really revolutionise
>things if it is indeed true (read no more water changes?).

	In my opinion, this is asking for trouble.

Paul Sears        Ottawa, Canada

Finger ap626 at freenet_carleton.ca for PGP public key.