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Re: Time to Dose PMDD, Get Rid of Green Water...

>Date: Mon, 06 Oct 1997 16:40:14 -0400
>From: Ryan Murray <rmm at acpub_duke.edu>
>Subject: When to dose PMDD?
>Hi all-
>Does it make a difference at what time of day one doses PMDD or other
>oxidizable trace elements?  In other words, is morning dosing inferior
>because of 12 hourse exposure to bright light?  Do plants use more trace
>nutrients at night or during the day.  I suspect that since growth
>occurs at night this would be the optimum time for dosing.  Any thoughts
>would be much appreciated.

Ryan... It shouldn't make any difference if you are consistent in your
dosing of PMDD.  The idea is to keep some base levels of certain
nutrients (Fe, NO3, etc.).  With this base level of nutrients always
present, the plants can always get some despite when their optimum
uptake time is.

In other words... the base level of nutrients is high enought that even
when the plants uptake as much as possible, there are still more
available.  So ultimately I don't think it matters.  Dose when it's most
convinient for you.

> Date: Sun, 16 Nov 1997 19:10:36 -0500 (EST)
> From: Christopher Clubine <cclubine at yorku_ca>
> Subject: Re: Green Water...
> Interesting post Mark!  But how do _you_ get rid of green water?


A nice water change to cut the phosphate level down a bit, and increased
dosing of Nitrates in my tank should do the trick.  I determined my tank
to be Nitrate limited... here's what happened (and my line of thought):

I decided to adjust my PMDD further on my tank (after having moved, and
never really having time to adjust it properly).  So I established my
iron level, and then checked my nitrates.  The nitrates were very high,
and so I started adding some potassium (in K2SO4) to drop the nitrates. 
Well, I started getting lazy and didn't check my nitrates often enough. 
Anyhow, this beautiful green water developed.  So I then checked my
nitrates and they were zero.  Here's my thinking:

Since iron was never really changed, the nitrates were of concern.  When
dosing largely with potassium, I allowed the plants to use up all the
nitrates and phosphates for a short time... until high nitrates
disappeared, and then there was excess K and P.  Now with the plants
limited by N, and K present by dosing... P was allowed to build up to a
high level.  And then *BOOM* green water.

So, I've done a water change and have stopped dosing the K, and
increased the N.  Plants are bubbling like crazy.  I also just bought a
Hach Nitrate test kit for the readjust, but am going to buy a Phosphate
test kit (hobby grade) today to check out if my ideas are correct.  I
predict that the Phosphate levels are still pretty high, but that the
green water will be gone in about a week.  Will keep you all posted for
those who are interested.  Thanks for your interest Chris.


pearlsco at u_washington.edu
How much does a fish need a bicycle like a man needs... ?