"Graham Broadbridge" graham at peachy dot org wrote in message . au...

I'm no chemist, which is why I posted all the relevant water chemistry.

Regards
Graham

Think of it like a balance, see saw etc. The CO2 is the acid and the
HCO3(KH) is the base. The pH is a ratio of both of these.
The CO2 is a gas and has an atmospheric component. The KH(HCO3) does
not. Therefore the CO2 can leak(be driven off if in excess) out or
leak into the tank(If the CO2 level is understaturated or you add CO2
to enrich your tank). The KH stays the same pretty much unless you
have a relatively few number of plants that can rip the CO2 out of
HCO3= CO2+OH.

You can get confused by the chemistry and theory or you can just
follwo the pH/KH/CO2 table.

Step one:
Measure KH, make sure it's around 3 degrees(~50ppm) or higher.

Step two:

Find the KH you measured and then find the right pH range for a CO2
level of 20-30ppm range on the pH/KH/CO2 chart

Step three add enough CO2 gas ONLY to achieve this pH.

That's it. Try and maintain the pH in that range while the lights are
on.

Maybe someone can explain how I can increase the kH without the pH going
through the roof and killing all the fish. I'm acceptable to all
suggestions.

Well fish live in nature seem to do fine with good sized swings in
areas with high plant denisities. They are not sudden and take most of
the day to slowly ebb and flow diurnally. Most productive systems do
this, some up to 2 full pH units and some shallow lakes with lots of
plants will go from pH 6 to a pH of 10 daily.

But keeping a certain pH locked in is just to supply the right amount
of CO2 for the plants. This is the name of the game, we don't add CO2
to adjust the pH, just supply the plants with CO2. Some seem to think
plants like a certain pH or KH, which is generally not true. All the
plants want is CO2/nutrients etc.

Regards,
Tom Barr