Re: NO3 and NH4 and algae

[Thomas Barr <tcbiii at earthlink_net>]

Well _you know_ I'd bite on this one.

> Although I need to add 0.2 ppm PO4 every day to keep the level between 0.5
> and 1.0 ppm, I only need to add 2 or 3 ppm NO3 twice or three times a week
> to keep the level between 5 and 10 ppm.  The fish and their food evidently
> account for the difference.

That's about right with a low fish load. I've gotten more uptake than that
but for most systems this is in line with uptake rates using fish and KNO3
alone.
You'll also notice something interesting here as well. A 10:1 ratio of NO3
to PO4 uptake. This is close the Redfield type ratio found in aquatic
plants, while algae are at 15-16:1 N to P.

> Nevertheless, I couldn't help wondering if the small amount of guanidine
> in FN might have contributed to my current algae-free situation.  Perhaps
> it gives some advantage to plants over algae.  I wrote to Dr. Greg Morin
> of Seachem, and this is his response (used with his permission):

No. The only thing this added NH4 form would do is add a small non visibly
kick to increase plant growth a little. Would that little kick be enough to
knock out the algae? Not in my opinion.

Would keeping careful track of dosing your N&P and CO2 levels help?

Most certainly.

Would neglect cause algae? I'll let you fill in and answer your own
questions....
My guess is that you have simply kept up on things, I can do the same thing
if I neglect and then get back on track and keep those N, P, CO2 ranges in
good order. When things get lean, the algae come out to play.

But being about to gauge how much you add of KNO3/KH2PO4 is the important
thing here. It's easier to add a product like SeaChem's stuff and get
results than wading through chemical ratios etc.

Glad to hear it's working for you, I have been saying it(N&P) does for some
time.
 
> "No direct evidence however many people reported either reductions in
> algae or lack of appearance of algae. This can be interpreted several
> different ways, (a) a component being added inhibits algae growth
> directly or 

Component or.......environment? Or a by product of good plant growth?
Elevated CO2, high DO levels and low BOD levels seem to correlate well with
low algae presence. There's a way to test for this and I will get to it
sometime. Humm, maybe sooner than I think.

(b) the algae growth is inhibited indirectly due to the
> plants out competing the algae because the component added increase
> growth response of plants or

I've said this many times, there's not competition because the nutrients in
the water column have an equal opportunity to interact with the algae or the
plants. Everything is there for for the algae and the plants. The algae are
not "limited" by lack of nutrients, there's plenty to be had for the algae
and the plants. When plant production drops off, then you get algae.

The key is keeping plant production going at a good rate.

 The fact of the matter is that plants need more nutrients than algae. So
this out competing notion is a very weak argument. If plants have the
nutrient available to them in the water column and these levels are
maintained, then the algae as well have the same availability to the
nutrients. How can something be out competed if they are in excess for both
the algae and the plants? They can't be. It doesn't occur. It might occur in
nature where someone is not adding nutrients all the time etc on a
consistent basis, but not here in the aquarium where you are maintaining N
level and P levels. It's always there for the algae just like for the
plants. 

If a nutrient is allowed to become limiting then nutrient limiting
competition can occur. Algae win this game every time. If you let the plant
by products build up like in a non CO2 tank, this is chemical inhibition
competition. Not nutrient competition. In a small space with lots of plants,
this can/does occur. Slow growth rate allows the plants to grow(much less
uptake of nutrients) but without the algae getting a foothold.

If some one wanted to look into a good idea for an algaecide etc, they might
look here. But it would take some time to work and there's nothing like
fresh plants that make these chemicals anyway. I also think at faster growth
rates like in the CO2 tanks with higher light you will find it more
difficult to achieve any degree of usefulness out of such a product.


> (c) the algae is out competed for
> nutrients because it is incapable of using the component added.

Well possibly with the complexed NH4.
But why would a plant be able but not an algae to use this? It is possible
but is this occurring? That is an interesting question IMO. I doubt it is
happening such that the algae cannot but the plant can use it but it might
be possible. Bio availability is something quite different.

> " My feeling is that (b) is the most likely here, with (a) a runner up
> and (c) the least likely. Further studies should be able to easily
> rule out (c) fairly easily (i.e. no plants in the tank and see if any
> algae grows under "ideal" algae conditions)."

Well you have no control nor have used it long enough to say too much just
yet. But I'd pick "a" and maybe if lucky "c".

I think the distinction between adding a little amount of NH4 and adding via
the fish is going to be slim at best. I think adding only NO3 as the only
source of NO3 vs adding NO3 plus a little bit of NH4 as a better is going to
be a rough argument from a practical standpoint. Still that being
said........I would add the same thing as Greg did here. The idea of binding
the NH4 into a non toxic form is a good idea and of interest. Whether the
algae have the same availability as the plants remains to be seen.

Regards, 
Tom Barr


> 
> I would be interested in other people's opinions.  Thanks.
> 
> John T. Fitch