Thank you for the numerous responses people!! You are all really really
helpful and I appreciate it.

Why do I measure my KH... I read on a persons site that had about 4 tanks
how they set them up and maintain them (plant tanks of course) that they
actually measure the KH (+GH) of the water before adding it to the tank and
they know exactly how much KH+ powder to put in every water change. They do
a 100lt water change once a week and they always put in the same amout of
KH+ powder to maintain a stable PH... Is this wrong?

I have since gone back to the stone age CO2 (no offence anyone) my regulator
and solenoid broke when I was trying to tighten it (I had a gas leak, 800gms
of gas was lasting 6 weeks, not 6 months and I got a head spin when I went
into my enclosed cabinet...) so I am now on DIY, which you really have
absolutely no control over!!!

I will take Nikki's advise and get a PH controler... I am opting in for the
Red Sea controler (availible in Australia in July, it will take that long to
save after buying a new car anyways) I did have a look at the Aqua Medic
controler Nikki recommended, but that is only for PH and not availible to us
Ozzy's. The Red Sea controler is for multiple sensors, the base model comes
with LCD display, sensor bank with PH and temperature probes and 1 power
controller unit which controls up to 4 power plugs. It can be programed for
moonlight etc. There is also optional software to download data stored on
the unit into your PC. I have cable heating and that is currently
controlled by a dupla T-control delta, so I will replace that with the Red
Sea controller and have an all in one solution...

wrote in message
ups.com...
pH controllers seem to be a waste of money for added complexity. Just
measure your pH with a cheap kit-the accuracy doesn't matter that
much-it's the change in ph before and after adding CO2 that matters!

You cannot intelligently use pressurized CO2 without knowing your KH
level and your pH change.

I also echo Nikki's question-what is the reason for changing KH? Also
her recommendation: read Chuck Gadd's excellent page on CO2 at
http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm