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Re: Nitrate additions

On Fri, 17 Sep 1999, Michael Moncur wrote:

>  >I have tested the water, and it shows no nitrate (Aqua Pharm test kit).  I
>  >am debating adding nitrate to shift the system to phosphate limited, and
>  >wanted your input (I have sodium nitrate in granular form).  My fears are as
>  >folows:
>  >
>  >- -Will the initial high phosphate AND high nitrate state cause a bloom of
>  >algae?
> I don't think so. When my tank was N-limited and high in phosphate, I had
> every algae imaginable. I've been adding KNO3 over the last month or so,
> and the algae has only decreased. I haven't seen any type of algae increase
> at any time. (They aren't all gone, but it's much better than it was.)

Actually, by definition if nitrogen is growth limiting and you add a
usable nitrogen source (e.g. nitrate) then you will get a burst of growth
- usually from the algae. The only time you won't see this is if there is
something else in there that is very nearly as limiting as the nitrogen.

If you add nitrate and you don't see a sudden increase in growth then in
all probability nitrogen wasn't the limiting factor to start with.  If
you do get a big increase in growth then you can expect this to continue
until some other factor becomes limiting.  That can take a while.

As I think Michael pointed out, if you want phosphorus to be limiting,
then you MUST stop using the phosphorus-based buffers.

Roger Miller