Controlling PH using CO2 for planted tanks

[AtodaJ]

I've been thinking about converting my 55 gallon into a heavily planted tank. I realize that I will require heavy lighting and a co2 system. My question concerns how you can control the PH level using co2.

Specifically, my tap water has a very high PH at 8.2. The KH and GH are also rather high. Its my understanding that co2 will lower the PH and that I can actually use co2 to control the PH.... by rigging up the system to maintain a 7.0 PH. Is that actually possible?

If the answer is yes... then what happens when I perform a 20% water change? Won't that create a temporary spike that will be a problem every time I do a water change?

 

[Guest]

Are those parameters taken after the water has rested for a few hours or right out of the tap? Also to really answer your question we will need to know the kH of the water. Without the kH it's impossible to answer most of your question. If your kH is very high you might not be able to use CO2 to lower your pH all the way to 7.0 without overdosing CO2.

A 20% water change will cause a short spike but it's nothing to be concerned about.

 

[AtodaJ]

When I let my tap water sit out overnight the PH rises a bit from 8 - 8.2.

As for KH... it is around 6-8 dh.

 

[Guest]

You will be able to bring your water down to 7.0 with no problems. In fact you might even want to go a bit lower, you could go to 6.8 with no problems.

 

[TankGirl]

I have a similar situation, and my CO2 has lowered my pH to 7 in my 55 planted (see my gallery), and my KH has dropped but just a tiny bit. Here is a great article for measuring CO2: http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm