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Re: PMDD/stalled growth

> I am trying to make a batch of PMDD according to the recipe. I have
> everything except the chelated trace mix. Does anybody know if i can use
> the Seachem's "Flouish Trace" for the trace elements part of it. The
> Guarantied analysis shows different percentages and other elements than
> whats on the PMDD recipe. And if yes, how much to use as opposed to the
> recipe. My plants are growing well but they seemed to have slowed down.
> Algea is under control.Tank is 80g,  lights are 3 110watt VHO, Co2 is by
> Carbo-Plus(Co2 by electrolysis), substrate is Flourite with medium fish
> load. I am hoping to get to the next level of the plants with
> faster/lusher growth. I appreciate some advice on this. Or where to get
> CTEM in LA?
> Hans S

Well recall it is a TRACE. Not that much is really needed. The
recommendations always tend towards the conservative side both from the
makers and the recipes. Also consider that lighting has gotten much stronger
since much of this has been written about and studied.
Most folks' common issue when trying to optimize a tank seem to lie in two
areas. 
1) CO2 (like I have not said anything about that one prior:-) (KH)
2) Macro nutrients NPK and sometimes Ca (GH issues).

So if your confident of CO2 levels being at 20-30ppm(even low lighting tanks
seem to benefit greatly from this level) and you think that the traces are
fine all that's left is the macro's. K doesn't need to tested really but
simply added to excess(K from KNO3, K2SO4, KH2PO4 or KCL etc) and then it's
a matter of ratios with N and P.

Perhaps a few plants benefit from a high N to low P ratio. Most seem to show
a preference to lower NO3 and higher PO4 ration IME. You will get high
growth rates on some plants like Eusteralis/swords etc with the higher
NO3's. But you'll get better crypt growth with high PO4 and low NO3 along
with nice red colors. I don't care for Sword plants as they get totally out
of hand and turn into trees but this does slow them down a great deal. Some
such as chain swords and the smaller ones are fine though.

In higher lighted tanks I found that the P is used up very fast and
maintaining a high level of either N or P seems to be much easier using the
N rather than the P. I can get a few days out of a dosing of NO3 compared to
trying to keep a low residual level of PO4. I've watched my tanks go from
1.0ppm in a steady linear line right down to zero in multiple runs with a
.2ppm average a day.

I'm not sure what optimal level of P is, perhaps .1 to .3 or so for a P
limited tank. It doesn't not seem to be an issue what it is in a NO3 limited
tank. 1.5ppm 1.0ppm or even 2.0ppm is some non conservative people(s). I
doubt anyone needs more than 1.0ppm for a week's worth of P.

It's okay to run at 0.00ppm for a day. *I don't want to run low for more
than day with these two. P is preferred if you do but get to it within 3
days.

I would suggest to add some PO4 source and watch what happens then you tell
me if I'm nuts or not. I know I am and admit it:)
Try adding enough KNO3 to get a reading of about 5ppm and a PO4 of about
.5ppm. Add more traces. Everything is going to be used faster as you add all
of this and growth will also increase. Not necessarily more mass but deeper
greens/different difficult plants will grow as easily as the easy plants
etc.
You have great light/substrate hopefully CO2 and you may wish to have some
current push the CO2 off that bar of the carbo plus unit to mix the CO2 in
your tank well if you don't already. If you use a pH probe turn the
CO2/lights off before taking a reading. They can often effect the reading
greatly.  

Well it's probably more than you wanted to hear:) But your answer likely
lies in there. Try PO4 first. Add enough NO3 to 5ppm. Excess K. Check over
the CO2. If things look like they are doing well then add more of the
traces.
The Flourish trace does not contain iron! This makes ideal for non CO2
tanks/fish only but I still have not done much in that area with it. But you
will need  a source of iron to be added to your tank at that high level of
lighting. I use the SeaChem Flourish line or Tropica Master Grow for traces.
Lots easier, not to mention more consistent when comparing notes with others
and my own mixing errors so I can focus more on the macro nutrients which
are used in greater amounts.
Regards, 
Tom Barr