Re:Fe

[Thomas Barr <tcbiii at earthlink_net>]

> Right now I'm working on a high-light 15 gal, 55W 6400K PCF from AH
> Supply.  In order to prevent iron deficiency using (H. polysperma as an
> indicator), I'm dosing 1ml of Flourish and 1ml of Tetra FloraPride daily,
> weekly 5 gallon water changes.  This is an uncomfortable level of trace
> additions for me, I'd like to see my dosages around half of this.

Why is it "uncomfortable"? What's the reason there?

> I've been browsing around Dennerle's site and also referencing this with
> Scheurmann's text and have concluded that my lighting levels may be a
> little too high.  I've come up with three possible "mechanisms" for why my
> tank needs so much trace:

 I have 2x that much light on some tanks.
 
> 1) High light, high growth rates which causes high uptake rates

Some is likely from this, how much? Hell if I know from a quantitative point
of view. I think the best one can ask for is how do the plants look? If I
add more will they look Better? Worse? etc.
Get the rest of the tank in what you feel is a good range, then manipulate
one variable at time. Give it at least 3 weeks before passing judgement.

> 2) High light, high growth produces too much O2 which rapidly oxidizes Fe

Add right before the lights come on then when O2 is lowest.
I've not noticed a difference here. ButI've not found a big difference
between adding 5 vs 6 mls every 3 days either. Is it oxidized?

I don't think so. It's go to the gravel, reduced down there and plants/algae
will grab it up once a again.
It's not "disappearing", just complexed, or turned to rust etc.
You can add rust to your gravel for an iron source if you wish.

> 3) High light causes photo-oxidation

Still, goes back to the last comment. Might have some effect.
Unless you are really keeping close tabs on the NPK,CO2 etc is difficult to
say what's happening.
 
> Of these three I think #1 is out because my growth rates aren't
> exceptional. 

Look elsewhere for your growth problem. Macro and CO2 are the main issues
for folks. Not enough traces is possible and does happen but they are
traces.........they are also a pain to measure due to that also.
You are adding more than enough traces and they are not "disappering" or
being oxidized to the point your light is the main cause of your poor plant
growth.

> Both Dennerle and Scheurmann mention excessively high oxygen
> levels being detrimental (redox is too high to keep Fe available).  Does
> anyone have any evidence of this?

What's meant by "excessively high"? Beyond 100%, 150%?
Which form of iron addition are they speaking of? Chelated Iron, iron
gluconate etc?  

> Can there be too much O2 production and
> is this causing the huge trace demands in our ("American") tanks?

We tend to have more lighting than most folks it seems to me. Does this
cause more trace oxidation? I tend to doubt this.
You can get high O2 values with 2watts a gallon also.

>  I've 
> noticed the Germans and Dutch use lower lighting levels than us, might
> there be some benefit here?

Sure, go back and read the listing I gave of high light vs low light leaves
a few post ago.

  But Amano's lighting in Nature World #2 is off
> the map; he's using 80W over 15 gallons?

So is my 20 with 110 watts of PC's and killer reflector. I can also do well
with 1/2 that light. It takes some getting use to switching around light
levels but you can grow tanks at low or high light levels.
Maybe he wants a certain effect.

 My nitrate is 15ppm in the tank
> b/c of very high tap levels, can high nitrate levels increase trace demand
> (Scheurmann states this also)?

As a function of NO3 uptake, I'd say so. But 5-10ppm vs 15ppm is not going
to make much difference for you there.
> 
> Wondering if he should run out and buy an O2 test kit,

they are fun and interesting to play with. Get one that goes to 15-20ppm.
10ppm ain't enough sometimes.

There's been talk of water with low KH/GH values needing less traces for
similar result. But simply adding a bit more solves that issue.


Regards,
TomBarr

> Jeff Ludwig
> Philadelphia