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- To: <Aquatic-Plants at actwin_com>
- Subject: Re: iron
- From: Thomas Barr <tcbiii at earthlink_net>
- Date: Wed, 01 Aug 2001 11:41:02 -0700
- In-Reply-To: <200108010748.f717m3w18987 at actwin_com>
- User-Agent: Microsoft-Outlook-Express-Macintosh-Edition/5.02.2022
> One simple conclusion seems unavoidable; the plants are *not* using the
> chelated iron that we diligently add and carefully measure. Rather,
> they are using the much lower levels of ionic iron that are released as
> the chelate breaks down.
I think you got it. Or they use the Fe3+ when they need it and convert it
themselves once they pull it in. Some let the bacteria do the work or the
It takes less energy to use the Fe2+ but it IS a trace element and does not
require a huge energy expenditure relative to the whole plant. Iron doesn't
evaporate either. I did not add any iron to the gravel of a number of tanks.
They did quite well. No laterite etc. Snail poop and traces add to the water
> Plants probably won't use the chelated iron
> directly unless they are already iron-stressed, which appears as a
> visible iron deficiency.
This could be plant species specific?
> Some of us avoid the visible symptoms of iron
> deficiency by adding very high concentrations of chelated iron to the
> water column. Ionic iron is only briefly available as the chelate
> breaks down, and keeping high levels of chelated iron makes sure that
> the ionic iron is always sufficient to meet the plants' needs.
Perhaps but the plants also get dosed 2-3 time a week so their Fe+2 needs
are being met based on the 20000 times or whatever excess we add.
> High iron levels could cause a number of different problems. The main
> problem is just that you apply way more fertilizer than your plants
> actually use. Also, many of us add iron in a trace mix and use iron
> measurements as an indicator for the adequacy of trace element
> concentrations. It is very possible that as iron levels are pushed
> higher and higher that some other trace element in the mix will reach
> toxic levels. Conceivably any of copper, zinc or boron (just to name
> three) could reach concentrations where plant growth is inhibited and/or
> invertebrates or fry are damaged.
Water change. Unless you get precipitates, copper etc or go plum wild and
overdose the heck out it. You types know who you are:) One guy added PO4
instead of KNO3 at 1/2 teaspoon levels instead of 1/2gram levels....
If I say 1.0ppm or so someone will add over 2ppm etc. More is better.
That's simply not true and will kill fish and not help the plants anymore.
At a certain point you simply just waste your fertilizers and traces.
There's a range that effective. More is wasteful and can cause problems, too
little stunts plants.
> Complicating matters even further, the level of chelated iron that's
> necessary to provide the desired concentration of ionic iron is going to
> depend on a number of poorly constrained variables. Commercial iron
> chelate mixes use at least three different chelating agents (EDTA, DTPA
> and gluconate), all with different decomposition rates. The
> decomposition rate of the chelate (and hence the supply of ionic iron)
> also depends on light intensity, light quality, temperature, and
> probably on bacterial activity. Further, some aquarists keep substrate
> conditions (generally, acidic) that might make it unnecessary to *ever*
> add iron.
Well not in higher lighted tanks. I've tried this now a few times. It does
depend on plant species to some degree. Lower lighted tanks in the 2 watt
range certainly I'd say yes to this. Maybe 3 watt a gallon. But the higher
lighted tanks need both unfortunately. I've tried to get around it but I
just don't think it's possible. To have good growth at higher lighting
levels, we need both sources(gravel and water column). But I get better
growth even on the lower lighting tanks with good high CO2 and nutrients but
less than the higher light tanks on the traces.
> If you need to add iron at levels that are pushing 20000 times the
> essential concentration then maybe it's time to look for be a better way
> to fertilize your tank.
Perhaps, but it works. Why? Why not do this also?
> Roger Miller