Is "dissolvability" cumulative

Bill Stock wrote:
"Elaine T" wrote in message
...

Bill Stock wrote:

I decided to add Potassium and Magnesium to the last batch of "PMDD" I
mixed up to save me the trouble of adding it separately. But the amounts
I needed to add to my stock solution to reach Chuck Gadd's recommended
dosages were above the amount of each compound that would dissolve in my
stock solution. So I reduced the amounts to levels that should dissolve
in my stock solution, but they still did not stay in solution.

I gather these "dissolvability" numbers are cumulative and not specific
to each chemical? Is the cumulative effect straight line or does it
depend on the chemicals being dissolved.

Just curious.




Yes, the amount of solids you can add to a solution is cumulative. The
effect depends on the chemicals being dissolved and some even precipitate
out in combination, like calcium and phosphate.


Thanks Elaine, makes sense based on what I'm seeing.

I was hoping to increase K and Mg above the standard PMDD strength to avoid
adding extra doses separately. I guess I could increase the size of my stock
container and just add more solution each week to accomplish the same thing,
but a 10 gallon stock container might be a little impractical.



ROFL! I was stirring forever trying to get a Plantex and potash mix to
dissolve this afternoon. I kept adding more and more water - it's half
the strength that I wanted. *sigh* Is it just me or does it seem like
you have to add incredible volumes of PMDD to get decent amounts of
ferts in the water? I'm looking at 1.5 ml per 10 gal per day of my brew
to try Tom Barr's Estimative Index dosing.

--
Elaine T __
http://eethomp.com/fish.html '__
rec.aquaria.* FAQ http://faq.thekrib.com

Elaine T wrote:

ROFL! I was stirring forever trying to get a Plantex and potash mix to
dissolve this afternoon. I kept adding more and more water - it's half
the strength that I wanted. *sigh* Is it just me or does it seem like
you have to add incredible volumes of PMDD to get decent amounts of
ferts in the water? I'm looking at 1.5 ml per 10 gal per day of my brew
to try Tom Barr's Estimative Index dosing.


Elaine, I made up two potions to solve this problem. My "tea" is
Plantex and magnesium together. I think it is 1 tablespoon each to
500ml water. My "pink stuff" is KNO3, KCI and a touch of KH2P04. I've
been talking to Greg Watson and at his suggestion I mix separate
batches to solve the solubility issue.

For what it's worth, I add 15ml of tea every other day and 20 ml pink
stuff every other day. The pink stuff is (I think) 4 TBL KCI, 1 TBL
KN03 and 1 tsp KH2P04 in 500 ml water. 55 gallon tank with C02 @ 30ppm
and full of plants.

steve

steve wrote:
Elaine T wrote:


ROFL! I was stirring forever trying to get a Plantex and potash mix to
dissolve this afternoon. I kept adding more and more water - it's half
the strength that I wanted. *sigh* Is it just me or does it seem like
you have to add incredible volumes of PMDD to get decent amounts of
ferts in the water? I'm looking at 1.5 ml per 10 gal per day of my brew
to try Tom Barr's Estimative Index dosing.



Elaine, I made up two potions to solve this problem. My "tea" is
Plantex and magnesium together. I think it is 1 tablespoon each to
500ml water. My "pink stuff" is KNO3, KCI and a touch of KH2P04. I've
been talking to Greg Watson and at his suggestion I mix separate
batches to solve the solubility issue.

For what it's worth, I add 15ml of tea every other day and 20 ml pink
stuff every other day. The pink stuff is (I think) 4 TBL KCI, 1 TBL
KN03 and 1 tsp KH2P04 in 500 ml water. 55 gallon tank with C02 @ 30ppm
and full of plants.

steve

Thanks! I'm not too far off your ranges then. I did something similar,
but I made a brew with Plantex and K, and a second with everything
because some of my tanks don't need extra N and P.

Dissolving K2SO4 surprised me because I was expecting solubility similar
to KCl. It took me a liter to dissolve 5 tbsp of K2S04 and 1 tbsp
Plantex. Since I had trouble with that one, I made up the full PMDD
formula (minus epsoms) in a liter rather than 500 ml.

--
Elaine T __
http://eethomp.com/fish.html '__
rec.aquaria.* FAQ http://faq.thekrib.com

On 2005-08-22, Elaine T wrote:
ROFL! I was stirring forever trying to get a Plantex and potash mix to
dissolve this afternoon. I kept adding more and more water - it's half
the strength that I wanted. *sigh* Is it just me or does it seem like
you have to add incredible volumes of PMDD to get decent amounts of
ferts in the water? I'm looking at 1.5 ml per 10 gal per day of my brew
to try Tom Barr's Estimative Index dosing.

Interesting - I've experienced the opposite. I've had to turn down my
concentration because it was too rich. I suspect it actually has to do
with the water in my current area. It's very rich in nitrate, and so
I've cut that out of my PMDD concoction. As a result, everything
dissolves easily ::-)

--
Ross Vandegrift

"The good Christian should beware of mathematicians, and all those who
make empty prophecies. The danger already exists that the mathematicians
have made a covenant with the devil to darken the spirit and to confine
man in the bonds of Hell."
--St. Augustine, De Genesi ad Litteram, Book II, xviii, 37