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Re: NutriFlex CO2/Reconstituting RO water

Jeff Malmquist wrote:

> I've just recently started working with planted aquariums in the past month.
> I have a 20 gallon tank.  I was talking with the folks at Albany Aquarium
> (which I have the luck to live near), and they suggested something called a
> Nutriflex CO2 system (They just got them in, and haven't tried them yet).

I guess my main comment is, don't take the advice of people who haven't
tried what they're advising you to do.

Aside from that, the system you describe sounds like a bigger maintenance
hassle than yeast CO2.  I hope the performance of this system outweighs
its burden of cost and maintenance compared to yeast+sugar water.


James Purchase wrote re reconstituting RO water:
> According to a chemist who works for a major aquarium products company (and
> who shall remain nameless), Kent's RO Right is merely a repackaged form of
> Aquarium System's "Instant Ocean" salt mix.

Gaak!  If that's right, then RO Right would give you water with
the composition of dilute sea water, which isn't much at all like normal
fresh water.  There's a big variation in the composition of fresh
water, but compared to "normal" fresh water, dilute sea water would
have a high sodium content relative to calcium, magnesium and
potassium and chloride would be high relative to bicarbonate and

We can do better than that.  Here's a recipe

Chemical 		dose/		dose/		measurement
			100 liters	50 gallons	unit

epson's salt		3.5		6.5		quarter teaspoons
calcium carbonate	6		11		600 mg tablets
baking soda		4		8		quarter teaspoons
potassium chloride	1.5		3		quarter teaspoons

IMPORTANT:  I don't use reconstituted RO water and I haven't tried this
recipe in my tanks.  Please refer to my first comment to Mr. Malmquist,
above.  I do or have before used all of these chemicals for dosing my
tanks.  If I go through with my plans to build a solar still, then I'll
probably use something like this to reconstitute the water.

The two recipes are very similar, and designed to produce 3 degrees
of general hardness, 3 degrees of carbonate hardness, about 10 mg/l of
potassium (per recommendation by Dr. Dave some time back), and proportions
of calcium, magnesium, sodium and potassium that I think are reasonably
balanced for growing plants; Ca:Mg = 3:1 and Na:(Ca+Mg+K)<1.

If you reconstitute your water in 50 liter batches (for instance) you
would use half the dosage for 100 liters.  If you resconstitute it in 20
gallon batches, you would use 40% of the dosage for 50 gallons, and so on.
The recipes should be used for water that originally fills the tank and on
replacement water used for water changes.  It shouldn't be used on water
added to make up for evaporation and it should definitely never be used as
a regular treatment to the water in the tank.

A couple years ago Neil Frank, with help from Paul Krombholz and Paul
Sears, posted a wonderful letter on how to dose different chemicals to get
different concentrations of important nutrients.  I'm pretty sure that
Erik has that letter at thekrib.com.  The recipe above is based partly on
the information in that letter.  It should give the following water

			dose/		dose/		measurement
			100 liters	50 gallons 	units

calcium			14.4		13.95		mg/l
magnesium		4.73		4.64		mg/l
sodium			14.24		15.05		mg/l
potassium		11.78		12.45		mg/l
bicarbonate		74.36		75.35		mg/l
sulfate			18.43		18.08		mg/l
chloride 		10.72		11.33		mg/l

general hardness	3.13		3.04		degrees
			55.7		54.2		ppm as CaCO3			
alkalinity		3.42		3.47		degrees
			61.0		61.8		ppm as CaCO3
Na/(Ca+Mg+K)		0.44		0.47		molar ratio
total dissolved solids	82.22		83.55		mg/l

The proportion of water in epsons salts varies (see discussion on this
list just a few weeks ago) so the amount of magnesium in this dose will
also vary.  If you want to get picky about the details, you could adjust
the epson salt part of the recipe till the GH comes out right, or you
could get an expensive hardness kit that measures calcium and magnesium
hardness separately and adjust the epson salt dose until the magnesium
hardness comes out to 20 ppm as CaCO3.

Also, the recipe calls for using 600 mg calcium tablets as the source of
CaCO3.  These are dietary supplement tablets, and they need to be as
nearly pure as you can find - as little color, flavor and binders as you
can get.  That probably means the cheapest product on the market.  The
tablets should be ground finely.  I use a mortar and pestle that my
sister-in-law gave us a few years ago for (I think) crushing spices. It's
kitchen ware, not lab ware.  The CaCO3 will dissolve slowly.

Potassium chloride is most readily available as a no-sodium salt
substitute.  In that form it isn't quite pure.  I use Morton's "Salt
Substitute" in my tanks.  It's about 97% potassium chloride.  The
remaining 3% is fumaric acid (harmless, I think) and phosphates.  I refuse
to fuss about the phosphates.  You can probably get potassium chloride
from a pharmacy or from a nursery, where is might be called "muriate of
potash".  The agricultural grade product would probably be impure.

There are some omissions and oddities in the recipe that might give some

There's no silica in the mixture, and silica is usually present in typical
fresh water at around 10 mg/l.  Silica is used by diatoms and some
grasses, but I don't know if any of our ornamental plants need it.  If you
want silica you can probably get it by adding a little sodium silicate
(water glass).  Check for it at your local pharmacy, or maybe even auto
parts store (it used to be used to plug small cracks in engine blocks).

There's no iron, other metals or trace elements of any kind - those
elements will be present as contaminants in the chemicals used for mixing
up the recipe, but not in any known quantities.  If you want to add them
you should probably get them from a hydroponics trace element mix.  There
are dosing instructions in Neil's letter and (I think) elsewhere.

Potassium at about 12 mg/l is higher than is usually found in water as
fresh as this.  I can't think of anything wrong with that, and potassium
should be good for the plants, but still it is a little odd.

There's also no nitrate.  If you want to add a little then you can
substitute potassium nitrate for some of the potassium chloride.  The
information needed to do that substitution is in Neil's letter.

There's no phosphate (unless it comes with the potassium chloride).
That might be a good thing, but remember that your plants must have a
source of phosphate. It's essential.

The pH of the mix will depend on it's CO2 content.  You might want to
check that the pH is reasonably balanced before you dump it in your tank.

As always, I'd much appreciate a careful review of these recipes.

Roger Miller