"Dave Millman" wrote in message
...
Sherry Michael Weller wrote:

I have found myself in the posession of a small DI unit. I know a bit
about DI water and I'm really excited to use it to process my 'liquid
rock' tap water.

I know that they sell additives to replace trace minerals and salts to
DI water. Can I simply mix DI water and tap to get the right GH?

Yes, this works fine.

I'm worried that the wrong PH buffers in any of these additives may
increase
algae blooms.

Using buffers to adjust pH is seldom good solution.


I know you can't measure the pH of DI water. My goal is to try to get
soft and slightly acidic water (peat treating if neccessary). If I mix
DI and tap, can I check the PH?

Yes. pH tests fail when chemical buffers have been added. Since you are
wisely avoiding that path, you should be fine.

I beg to differ..... pH test don't fail when using buffers......
All tanks with any kH or gH are buffered. Buffering is what
controls/stabilizes the pH at any given value. That is the reason you need
some kH, if the kH falls too low the slightest addition of acidic or
alkaline material can cause major pH swings and really mess up fish.

The kind and nature of the buffering controls the pH. Typically the
aquarium is buffered by bicarbonate, the higher the kH (all other things
being equal) the higher the pH. The reason you can't easily drop the pH in
a tank with a limestone block by adding acid is that the carbonate helps
maintain the bicarbonate level.

Many of the cheaper buffering compounds are phosphate compounds and can
cause trouble in a planted tank. They also can cause algal blooms in some
circumstances. There is no real reason why you can't use pH buffers to
adjust the pH in water that doesn't suit your fish. That said, I'd agree
that "natural" methods are certainly probably better. My tap water has too
high a gH/pH for angels to say nothing of the gH. I use RO water to get the
gH into the a better range and CO2 knocks the pH down below 7.0. RO water
is expensive, if I didn't have the gH problem and wasn't using CO2, I'd use
something like Seachem's, acid buffer to control the pH. As it is
because I use RO water I have to do occasional water changes with tap water
to maintain a reasonable gH for the plants and add baking soda to maintain a
kH around 4-5.

What fails when you use a phosphate buffer is the relationship between kH
and pH than can be used to calculate the CO2 concentration. Chuck Gadd's
calculator doesn't work if the buffering is due to something other than
bicarbonate.

Bob