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RE: New PMDD Confusion

Mark Fisher posted:
> Pat Bowerman posted:
>> The last e-mail that I received from Kevin Conlin listed the
>> "new" formula as follows:  <snip>
2 Tablespoons KNO3 + other dry ingredients into 300ml water
>> And Tim Mullins posted:
>> Conlin and Sears' latest PMDD formula:
>> mix with water to make a 1/2 liter solution, <snip>
1 tablespoon KNO3  (more or less, depends on nitrate) + other
dry ingredients.
> I can already hear someone wanting to try PMDD asking
> "do you make a 300 ml solution or a 500 ml solution?"

On Strength:
   -  I agree, one standard strength would sure be less confusing!
   -  Ratios of ingredients are key, strength just impacts dosages.
   -  Pat and I both referred to posts by the "Canadian Authorities"
      Conlin and Sears. I bow north and defer to them.  :-)
   -  Given KNO3 is not easily soluble, does not the higher
      300ml concentration have more settling?
   -  With the 300ml concentration form, are not small aquaria
      more difficult to dose since dosages become even smaller?

On KNO3:
   -  NO3 additions can't really be standardized since conditions
      vary: mains water can have NO3, fish result in NO3 (sometimes
      a lot of it), degree of planting impacts NO3 utilization, amount
      and regularity of water changes effects NO3.
   -  I tried to gear my post towards a novice. Not knowing a given
      user's aquarium profile, I thought initial conservatism was
      warranted. Plus, I assumed a novice is more likely to start
      with a natural excess of NO3.
   -  I agree, more KNO3 will often be necessary to get to 5mG/l NO3.

On Dosing:
   - I hadn't seen much on dosing so I resorted to calculation and
     empirical results. Thanks for sharing your results.
   - I only suggested a 1/12 ml to 1/6 ml dose of the 1 tbsp KNO3
     brew as a reasonable starting point. You're quite right,
     adjustments may well need to follow.
   - For the remainder of this post, I'll approximate dosage impacts
     using the following assumptions:
       -- Doses, in ml, are made into a 10 gallon tank.
       -- Daily dose for seven days, 25% water change, repeat.
       -- For simplicity, no depletion other than water change (a
          bad assumption, but useful for ballpark estimates)

> Also, the "old" recommended dosage was 3 ml/100 liters, or
> 1.1 ml/10 gallons, which resulted in a 3 ppm NO3 concentration
> for me.

I think the "old" formula included 1 teaspoon KNO3 and 1 of trace. So,
      -    Single 1.1 ml dose     Daily 1.1 ml dose  Comment
      - NO3   .31 mG/l                  9  mG/l     ok, high end
      - Fe    .02 mG/l                 .64  mG/l    quite high

> Using the new formula (one tbsp KNO3 in a 300 ml solution),
> I should be dosing at 1 ml/100 liters to give me the same
> NO3 concentration.

Yes, three teaspoons in a tablespoon.

> but a 500 ml solution would require 1.67 ml/100 liters. Yes,
> it's the same amount of KNO3, but tough for someone 
> starting out.

I see, you hope to tailor the strength so every ten gallons
requires an integer number of ml. Good thought!

> The new recommended dosage of 1/12 ml/10 gallons (from a 500 ml
> soultion, 1 tbsp KNO3) would be about 1/8 of the original dosage
> recommendation, and would result in 0.4 ppm NO3 for me.

Let's see, 1 tbsp of KNO3 in the 500 ml brew provides
      -    Single 1/12 ml dose   Daily 1/12 ml dose  Comment
      - NO3   .04 mG/l                  1.2 mG/l   ok, low end
      - Fe    .003 mG/l                .08  mG/l   ok, low end

Using 2 tbsps of KNO3 in the 500 ml brew provides:
      -    Single 1/12 ml dose   Daily 1/12 ml dose  Comment
      - NO3   .08 mG/l                  2.3  mG/l   ok, depends
      - Fe    .003 mG/l                 .08  mG/l   ok, low end

As you might recall from my post, I said doubling the dose may be
in order for a heavily planted tank. So, 1 tbsp of KNO3 in the 500
ml brew provides:
      -    Single 1/6  ml dose    Daily 1/6 ml dose  Comment
      - NO3   .08 mG/l                   2.3  mG/l  ok, depends
      - Fe    .006 mG/l                 .16  mG/l   reasonable

Using 2 tbsps of KNO3 in the 500 ml brew provides:
      -    Single 1/6 ml dose     Daily 1/6 ml dose   Comment
      - NO3   .17 mG/l                   4.6  mG/l   ok, depends
      - Fe    .006 mG/l                 .16  mG/l    reasonable

> Shouldn't it [dose] be 0.63 ml per 10 gallons,
> or 1.67 ml/100 liters?

If you did, 1 tbsp of KNO3 in the 500 ml brew provides
      -    Single .63 ml dose     Daily .63 ml dose    Comment
      - NO3   .31 mG/l                  9  mG/l      ok, high end
      - Fe    .02 mG/l                 .64  mG/l     quite high

> I thought the purpose of the new formula was to increase
> the macronutrients, not decrease them.

Yes, that's my impression too. I think it arose when Kevin
Conlin stopped using a UV sterilizer that was reducing 
his Fe chelates.

> Is my math off?  Am I off?  I understand we each need to
> tailor PMDD for our aquariums, but these new dosage
> recommendations seems to be low.  Anybody else want to
> give it a shot?

Admittedly I'm a little light on the NO3 after you consider
my approximations assumed no depletion; but, I thought it 
best in the interest of not steering novices wrong. 
I also have found these dosing levels to be effective in
my own tanks. Oh, as I've pointed out,your level 
of Fe dosing does seem high. Where have your actual Fe
readings come in?

Thanks,
Tim - Pittsburgh