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Re: PMDD dosing

> Date: Sat, 23 Feb 2002 14:34:03 -0600
> From: Douglas Guynn <dguynn at nwol_net>
> Subject: PMDD dosing

> For my 70 gallon tank, that translates to slightly more that 1 ml/day (2
> mls/day since I use 2 solutions). I am dosing more than 11 mls\day of each
> solution (20 mls total), and still showing no iron residuals. My nitrate
> test is either contaminated or old, so I'm not sure what that concentration
> is.
> Other tank parameters are
> pH ~7.0
> GH = 14
> KH = 6
> NO2 < 0.3
> 160 watts standard fluorescent lighting
> CO2 - 15 to 20 ppm (from chart)
> Douglas Guynn
> dguynn at nwol_net
> 915.368.5411


Hi Douglas,

    This sounds like a lot of PMDD to me. My first suggestion (and personal
pet peeve!) is that your test kits might not be accurate. What are you
using? Anybody you can double check your results with. If not make up a
known concentration and test your kits against this. You can find the into
you need to do this at the Krib at
http://www.thekrib.com/Plants/Fertilizer/pmdd-tim.html  Scroll down to the
subhead "Nerd Stuff...".

    As a basis of comparison, I have a 100 gallon, heavily planted tank
running at about 3.5 watts/gallon, and am currently dosing at 4ml/day. I
have a REALLY heavy fish load in that tank, and change 25% of the water
weekly. I can't imagine what sort of plant growth/density you would have in
your tank that could be making use of that level of nutrients. Again for
comparison, you can see a photo of my 100 in the last AGA showcase at
It's a pretty heavily planted tank.

Hope this helps,

Ron Barter
Perth, Ontario