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Re: Seachem Florish and KH question

In Digest 3:1263  IDMiamiBob at aol_com said:

> Most "tap water purifiers" capapble of removing phosphate will not remove  
> sodium chloride (NaCl), indeed they tend to rais the levels of Na, and  
> usually also Cl.

"Most" is far too much of a generalization here.

Home water softeners replace Ca and Mg with Na, and you do indeed get
just as high a level of dissolved solids as you started with.  Do they
also replace CO3 with Cl?  I don't know.

But the most widely sold tap water purifier in the U.S. fish trade does
not do this.  (I'm referring to the thing called Tap Water Purifier from
Aquarium Pharmaceuticals; I don't know what's sold in Oz,) It replaces
the metal ions (cations) with H+ and the CO3 etc (anions) with OH-, which
neutralize each other. The output has 0 parts per million of dissolved
ionic solids when measured with a simple conductivity tester.

Of course, using this water directly would be very bad for the fish
population.  The 20-40 ppm level that you mention may be too low, but
that depends on how it was measured (conductivity test? GH test kit?)

With the species that you list, the hardness numbers that you're aiming
for are perfectly reasonable. Most common fish species, apart from discus
on one end and lake cichlids on the other, aren't very finicky about
total hardness.  (Oh, and down with cruelty to mollies! -- which don't
belong in soft water.)

It would be a good idea to find out the basis for the claim that there's
too much phosphate in the water, to avoid possibly wasting effort and
money on purification that's not needed.  Your municipal water supplier
ought to give you an analysis, which would save you buying a phosphate
test kit.

> >I thought I would try and raise both the hardness and 
> >  alkalinity.  I thought that raising the kH might stabilise the pH which is 
> >  normally about 6.8 but with CO2 can get down to under 6.00.   
> CO2 injection causes the formation of carbonic acid (H2CO3).  Because  
> alkalinity is primarily a measure of CO3, the CO2 injection will stimulate a  
> lowering of pH no matter what the kH is.  The pH will still go down.

Adding CO2 will always lower the pH.  Raising the KH _will_ allow you to
get more CO2 in the water (good for plants) without so much lowering of
the pH (which can be bad for fish).

You may end up taking stuff out of the water and putting some of the
same stuff (CO3) back in; but _if_ you have too much of the wrong stuff
(PO4) to begin with, it may be worth your trouble to just that.  Still,
maybe you should look into the various phosphate removers, which could
save you a good deal of expense and trouble if they do the job you need.
I've never used them (thank you, Marin Municipal Water District, for 0
ppm of PO4, NO3, Fe, and most other things) so I don't know if they'd

Dan Drake
dd at dandrake_com