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Re: Seachem Flourish and KH question

on 01:48 AM 9/8/99 , Aquatic Plants Digest wrote:

 >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.

I believe he was talking about *the* Tap Water Purifier, a product from 
Aquarium Pharmaceuticals. If I'm not mistaken, it's a DI resin thing and 
not an ion-exchange system, and thus doesn't add NaCl. Its output should 
basically be the equivalent of distilled water with zero KH and GH.

 >Your water is in all likelyhood already salty enough, or even too 
salty.  Get
 >a copy of the water quality report from the local water authority.  See what
 >you have.

This is a good idea, as is paying close attention to what any "purifier" 
does before you use it.

 >Because most water purifiers (and I am out on a limb making this
 >generalization) replace CaCO3, MgCO3, and a host of less common compounds of
 >phosphate and the like with salt.  Yea, NaCl.

See above.

 >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.

I'm sure this is true in theory, but doesn't a higher KH make the pH change 
due to CO2 smaller? I'm bubbling quite a bit of CO2 into my 29G tank. My 
tap water is 40% well water and has 7 dKH. I am unable to detect any change 
in pH at all when turning on the CO2, turning it off, after a day's usage, 
after turning on an airstone, ad infinitum.

I am, fortunately, able to detect a dramatic increase in plant growth, so 
apparently the pH change isn't everything.

 >  You ran
 >the water through a purifier, and whether it was your intent or not, the
 >majority of what the purifier did was to take out CaCO3.  Now you want to
 >increase the level of CaCO3.  Stop using the purifier.  It will save you
 >money, and effort.  Confirm with your water utility or your own tests what
 >phosphate levels are.

Here I agree. The mere presence of phosphates shouldn't force you to go to 
such extremes.

 >You've already increased the salinity by running it through a purifier.  The
 >amount of salinity you will boost it by (130ppm) is pretty high, on top of
 >that.  This is probably not very good for plants at all.

See above.

(On a related topic, Neil Frank writes, later in the digest...)
 >some trace elements or may need more light to generate enough O2 or...). If
 >you have visible algae, then your tank is probably not low in N. I
 >discovered a long time ago (pre-PMDD) that I had to add nitrates when the
 >plant groth slowed. When a tank is limited, there will be other signs --
 >like languishing duckweed. Duckweed is a good indicator plant and is
 >cheaper than a test kit.

My tank, FWIW, was growing huge colonies of algae while being utterly 
N-limited, no detectable amounts on any test kit. The alga were apparently 
happy with my tap water's ample phosphates. Adding a daily regimen of KNO3 
has reduced algae to manageable levels. I have some rather dramatic 
before-and-after pictures on my in-progress Web page:


My duckweed did disappear completely, so I'm sure you're right about that.

michael moncur   mgm at starlingtech_com   http://www.starlingtech.com/
"If we don't change direction soon, we'll end up where we're going."
                 -- Professor Irwin Corey