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[APD] RE: PMDD



> > No, iron testing is difficult and does not realistically tell you what
you
> > need to know. How much iron the plant needs.
> > Test kits vary a good deal and the time of the test after you take the
> > sample and add the dose also matters a great deal as you have likely
> > figured out.

> Alright, I'm just confused why everywhere I look people keep saying to
> maintain a 0.1ppm iron level :-/  I guess I'll concentrate on the others
> you've suggested.

This was a level from the paper and is why it's so wide spread, similarly,
folks still seem to think that low PO4 limits algae and helps the plants
also, this is not true.
Can you limit two nutrients at the same time? No, not really. I can assure
you 0.1ppm is a great deal of iron that is also available to algae and that
0.1ppm of PO4 is plenty also. I know of no FW alga that would be anywhere
near being limited at those levels. If anyone does, please step forward. 

> > You should deal more with the CO2 and NO3.
> > Traces are best gauged by adding progreesively more till there is no
> > improvement in plant health when the CO2,NO3, K+, PO4 GH are in good
> shape.
> > Give each amount of trace that you try, about 3 weeks time.
> > Once you determine this amount, stick with it and remember the plant
> > biomass you had, if it doubles, you'll need to double the dosing for the
> > Trace mix. Dose at least 2-3x a week.

> Ok, I've been trying to dose about 1/day w/2tsp to keep a better level of
> nutrients available, if I do it less frequently I'll likely forget :-0 
Bad?

Try at least 2-3x a week, daily if you feel this is a better habit for you.
Just split the increments up by 7 instead of 2-3. So say you add 10mls 3x a
week, now you'd add 30mls/7 = 4-5mls a day etc. 
I used CMS at 500ml of water in 2 level tablespoons and add like I do
Flourish, roughly 5mls per 20-30gal 2-3x a week. 
So you can scale up and start with 5 mls daily.

Do this and the PO4 only ____after____ you have made certain the CO2 is
good, the K+, NO3 are good and the GH is good.  

> > How big is your tank and how much light for starters.
> 90G w/overflow (all-glass).  Two Smart Lite (Custom Sea), 48". 2x2x65W =
> 260W total.
>
> I also measured my nitrates tonight, they're just about 4-5ppm.  KH is
kept
> at 4 degrees, pH 6.8, GH 2 degrees. 

GH seems low, I'd add a touch of MgSO4 after the water change only, maybe
1/4 teaspoon and then some Ca++, either CaCO3 finely ground powder etc or
CaCL2(about 1 teaspoon)

 Compressed CO2, home-made reactor,
> home-made bio filter w/5g bio balls, about 500Gph (750gph pump).  Laterite
> (20lbs) in substrate (quartz), about 3" deep.  Anything else?

Double, triple check the KH/pH to make certain that the CO2 level is good,
check the am/pm pH changes and compare to the pH/KH/CO2 chart.
Be very critical of this part.
Shoot for a pH target of 6.6(30ppm of CO2), this wille error on the high
side and you should see better growth in the plants.  

> The plants look like they're defficient in something.  They're yellowing
> from the edge of the leaves toward the center stem.  

GH, low Mg unless you have been adding it with the PMDD mix.

I hope this is a
> potassium thing because I haven't been dosing that yet, hoping to see some
> results from the trace mix.  How long should I continue with the trace mix
> (it's been about a week) before I introduce the K2SO4? 

Add K2SO4 right away, but if you add KNO3, you already add enough K+ unless
you dose very little. Unl;ess you have a very trustworthy NO3 test kit, eg
a Lamott/Hach, I'd rather see you do a 50% water change, assume that the
NO3 is 4ppm and then add back 3/4 teaspoon of KNO3 teaspoon and assume the
NO3 is very close to 10ppm. 

Yellowing could be many things. 
Rather than trying to figuire what pasrticular nutrient it might be, cover
all your possible nutrients with doing regular large water changes. Add the
nutrients back and then the next weeks water change will remove any build
up. That way nothing runs out and nothing builds up. 
And the accuracy of this method is close, if not closer than most test
kits, all you do is keep a good eye on the pH/KH for CO2.

 Or should I really
> just mix them all back together and try to ramp up the ferts while holding
> the parameters you've mentioned steady?  Or...wait another two weeks doing
> the trace before introducing others.

Just give the routine about 3 weeks to pass judgement on a Trace dosage. So
try adding 5mls daily and see how plant health does.
You need to keep the K, NO3, Ca/Mg, PO4 up in a good range and everything
goes sour if the CO2 is low the last 1/2 of the day so make sure the CO2 is
good during this time and figure out a way to keep it steady around
20-30ppm or so, error on the high side. 

> Thanks so much!
> Dave T.
>
 Regards,
 Tom Barr



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