Re: Muriatic Acid - HCL 34% and TDS/conductivity

[LeeH920226 at aol_com]

RJ,
    I am a retired chemist and I have used muriatic acid in aquariums. I 
diluted the commercial strength stuff to a nominal 1% solution and then used 
it dropwise at that 1% concentration. It moves the pH very quickly with a few 
drops even at that concentration. I stopped using it when my water supply 
started coming in at a lower pH and also because I started using peat 
filtration to lower the pH.
    I must also caution you about handling the 34% material. Keep it from 
your eyes, protect your hands and don't breath the fumes. Also you should add 
one ml of the 34% stuff to 33 ml of DI or RO water to dilute it. DO NOT add 
water to it -- it heats up and can be dangerous.

    As far as TDS and conductivity. They are related and different. Any 
conductivity is induced in water by dissolved ionic materials - mostly 
solids, but gases like hydrochloric acid (muriatic acid 100%) can also cause 
increased conductivity. Most commercial TDS meters are simply conductivity 
meters with a different scale. The conversion from conductivity to TDS is 
normally done for the meters by using potassium chloride and a 2/1 conversion 
factor. However, most water doesn't contain potassium chloride, but a 
combination of other salts, so the conversion is more like 1.7. So a 
conductivity of 200 microsiemens/cm is converted by the meter scale to 100 
ppm but in actuality it really is about 120 ppm. The absolute number is less 
important than the approximate number. The most important thing is the sudden 
changes which can kill fish, especially when going from higher to lower 
numbers.

Lee Harper
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