Nick, I don't think anyone can express the loss in ppm, there are just
too many variables for any such calculation. The only way to really
know is to turn the wheel off and see what the resulting CO2 level
becomes over a period of 6-12 hours. Having said that, based on your
KH and PH it would appear that you have sufficient CO2 in the tank for
a medium-high light tank. It may just mean you'll need to refill the
DIY CO2 bottle more frequently to maintain a level in the 20ppm range.

Hope that helps
Giancarlo Podio
http://www.gpodio.com

(Nick D) wrote in message . com...
How much PPM do you reckon I would lose off the biowheel on my Penguin
filter?? I have DIY CO2 on a 29gal heavily planted...
PH 7
KH 7

thx
Nick