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Re: Aquatic Plants Digest V2 #1098


>                                                           Will the water
> conditioners we use adversely affect the macro and trace elements we add
> at water changes?  Thanks in advance.
> Only 233 QYNGAs to go George! <g>

I don't know the answer to this, so I'll sit on the sideline and cheer for

> - ---------------------------------------------------------------------


>                             "100,000 times slower" diffusion rate in
> water sounds like we're going to need a mighty force indeed!<g>  Any
> practical advice here?

I don't know how practical this is, but...  As I understand it, breaking
down the Prandtl boundary requires that you have high enough water
velocity across the leaves that the water near and at the leaf surface is
flowing turbulently.  I went back to my old fluid mechanics text (stupid
thing to do) and calculated that for the ideal, smooth, rigid submersed
plat (model leaf) the transition from laminar to turbulent flow would be
at such a high velocity that you will probably never see it in your tank.
However, if the leaf actually moves, then I think you automatically get
turbulent conditions, and that happens at a much lower velocity.  So it
looks to me like you need to have enough water movement to actually move
the leaves.  Probably about any leaf movement is enough.

> - --------------------------------------------------------------------
> Since I'm on a roll, how about a 3rd question?  I've been practicing
> "patience" with a green water problem in my 3 mo. old rainbow tank.
> I've been testing to see if anything unusual is going on.  The biggest
> surprise is nitrates.  Despite the fish load and the addition of 4-8
> mg./l nitrate (from KNO3) at water changes, the nitrates drop to 0.0
> (LaMotte) within a few days.   Other tank parameters:
> 40 gal. reg; pH 7.2 (mornings) ~7.4 (afternoons); GH 5; dKH 10
> CO2 12-20 mg./l; phosphates - always 0.0 (Hach)
> fish load: 6 boesmani rainbows (~ 3"); 6 ottos
> plants: 85% planted with H. poly; E. tennellus; Limnophila;
> 	Java moss; R. macranda; R. magenta, E. bhleri
> filter: 2213 Eheim with surface extractor
> substrate: 3-4 in. of 2-3 mm sand; w/ dupla laterite (and
> 	the root starter included in one box) in lower 1/3rd
> water changes:  50% per week (recently 50% twice a week)
> fertilizer: 5ml Tropica Mastergrow; 1/4 tsp KNO3; 1/4 tsp
> 	Epsom salts (at each water change)
> lighting: 110 w compact fluorescent w/ 6700K bulbs--10-11 hrs/day
> tank condition: in addition to the green water, it's been cycling
> 	through various types of green algae with the H. poly and
> 	E. tennellus taking the brunt of it; growth has been fast
> 	after infested portions are removed
> Any ideas?  I've been wondering if the lighting isn't too bright.  But
> since several recent notes have commented that cf lighting doesn't
> produce more light per watt, I should be okay at 2.75w/gal? Right?  My
> LFS thought a "micron" filter pad would filter out the green algae (the
> label said it would filter down to 10 microns in a canister).  I added
> 4 layers to the Eheim with no effect on the green water.

Your LFS wants to sell you something.  It's their job.  They do it well.

I have seasonal green water problems with a couple sunlit tanks.  also, I
increased lighting on an established tank last winter and triggered a
round of green water and moderate fixed algae blooms.  Here's what I

   High light levels allow green water blooms, but can't be treated
as the sole cause.  Reducing light levels is probably not a great
solution, particulary if you want to keep high-light plants.

   Bigger and more frequent water changes treat the symptom, not the
cause, and don't work very well anyway.  In some cases if you stop the
water changes and let the tank stabilize the green water will go away
without any additional work.

   Green water blooms were related to iron fertilization.  I stopped using
it and the green water disappeared quickly.  I let the tank stabilize and
afterwords I was able to gradually worked the fertilizer back up to a
useful level.

    Filter feeders help.  I use clams.  Other people use daphnia.  I'd
like to find some other options.

    Planting more rooted plants might help.

> Thanks, Steve Dixon

Roger Miller