Re: nutrients

[Thomas Barr <tcbiii at earthlink_net>]

> I was hoping that I could get some help with the nutrient levels suggested
> by Tom Barr.

You just cain't trust him:-)
 
> DFWAPC - Fe .2 or higher(?) / PO4 .4 -1.0ppm / NO3 5-10ppm / K+ 20-30ppm
> sfbaaps   -  Fe .2 -.7 ppm      / PO4 .2 -.5ppm   / NO3 5-10ppm / K+ 20-30ppm


These are slightly different due to the DFW stuff being more up to date.
What is an Fe measurement? What does it mean regarding plants? I don't think
we have the tools to really address a measurement that will directly
correlate with good plant growth.
There are indirect methods.......but it's the art, the eye and the
experience with plants. Some close approximations are all that's need but
fine tuning is up to the user(generally not needed).
You get all the other's within a "good" range then manipulate the variable
of interest, in this case Fe.

I use volume of traces/tank volume/time as my unit.
You can convert this into micrograms of Fe uptake per day(or some unit of
time) for the tank or weight of plant material and also do a dry weight % of
Fe to see how much is actually taken into the plant vs how much total you
added. There will be some loss of Fe to the water/precipitated etc.

But this is not necessarily the plant's "need". Plants take in extra
nutrients like Fe/NO3/PO4 etc. More than they need to grow, this is often
called "luxury uptake". Plant cells can store a fair amount of NO3 in their
vacuoles for example.
 
> The first question is, are these levels just for CO2 tanks? I have a 125g
> tank with approx. 2.5 watts per gal. PC which I use Seachems Excel in, so I
> was 
> wanting to know if it would be safe to target these levels.

Yes, this should work ........provided......you are getting enough carbon to
the plants this way.

Now here's a question for you.

How do you know if you have enough Carbon or not?
Yea, I know there are directions etc but the plants are the best gauge.
If you have not done well with CO2 gas, seen a number of well run planted
tank in person, then it's likely you have a reference point. Excel etc will
help but it is not going to have the same effect as CO2 when you have this
much light.   

Carbon is the main issue, then NO3.
If these two are messed up/limited, run out etc, generally here's trouble.

Non carbon enriched tanks are another matter.

2.5 watts of PC lighting is not the same as 2w of NO lighting. It's like
3-3.5w of NO lighting.

You are pushing with the Excel, (expecting) too much I would think at this
light level. If you have less plant mass etc if might be different, but
generally speaking, I would not try this and with a 125 gallon tank I would
find this very impractical although Greg from SeaChem will like you:)
 
> I see different growth rates in my plants sometimes and I would have to
> believe that the nutrient levels being low would have to be the cause for
> this.
> For example: I have some Rotala rotundifolia which grows very fast most of
> the time and then every once in a while the growth seems to slow way down.

So back to the main issue, carbon.
How will you test for it?

The run down is Light=> CO2/carbon => NO3/NH4 => K+ => Traces => PO4.
The traces/PO4 status is not clear which is "more" important for aquatic
plants.

But I tell folks to work from the light on down like this. Get each one in a
good range, then, progress to the next nutrient down.

> The nutrient levels in my tank are as follows PO4  .4 ppm / NO3 5ppm / Fe
> .1ppm 
> I really would like to up the NO3 and Fe but as stated above are the
> recommended levels for non CO2 tanks?

The levels for a non CO2 tank are extremely wide.
Substrate plays a larger role etc
Don't jump between Carbon enriched and non carbon enriched methods.

If you plan on going this route(no Carbon enrichment), then let us know.
I will adjust the advice to a large degree should you choose this path.

> The next question is about the difference between the Fe and the PO4 on the
> suggested levels. I am assuming that your current recommendation is the
> levels 
> suggested on the DFWAPC site, would this be correct?

Make sure you have some every 2-3 days etc.
Precise control over these levels is not something that will make/break a
tank. Some every 2-3 days even if the levels are zero hours later will
suffice.

Precise control over having enough CO2 and enough but not too much NO3 is
much more important in routine day to day plant tank keeping.

Test kits vary in $, quality and accuracy.
People and laziness varies.

I like a simple non testing method except for CO2(pH/KH).
One hell of lot less work. Then I can be lazier:-)
 
Regards, 
Tom Barr

> Thanks for your help,
> Bill