pH/KH/GH chaos. Advice needed.

[aquatik]

I have a 55gal. planted community tank.

10 Cories (melini,julii,green,panda)
7 Pristellas
4 Black phantom tetras
12 Zebra/leopard Danios
1 Clown Pleco

10-12 plants: mainly low to moderate light plants. (amazon & brazilian swords, anubias 'barteri, etc.)

260watt Coralife

-NO CO2- yet. CO2 level appears to be around 5ppm though.

Eheim 2026 (added it 5 days ago.)
H.O.T. Magnum 250 (running until the eheim has estab. bacteria colony)
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Now for my problem: water chemistry.

In-Tank:

pH: 7.3-7.4
GH: 3.36dH (soft)
KH: 2.80dH (low buffer)
Ammonia: 0
Nitrite: 0.1-0.2ppm
Nitrate: 10-20ppm

Tap water (water changes):

pH: 7.4
GH: 3.36dh
KH: 1.68 (very low buffer)
Ammonia: 0
Nitrite: 0
Nitrate: 0
(I find my tap to be quite odd. Considering the low GH/KH with a high pH.)
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OK. Now you have the details, here comes the request for some advice. =)

I'm thinking of adding C02 for my plants because of the amount of light I'm using. 130watts for 8hrs 260watts for 4hrs.

Should I gradually raise the GH/KH/pH values in my tank before adding CO2 to prevent a pH crash? I have hardly any buffering capacity in my tank or tap. For the past month I've slowly increased the tank KH using baking soda. As you can see, it's only raised about 1dH from the water I use for changes.

I'm worried adding co2 will cause my pH/KH/GH to swing out of control. And ultimately a total imbalance. Are my water parameters unsuitable for a planted tank?

Is my water more suited for a non-planted cichlid tank? Or will I have to do water changes weekly to combat a low buffering capacity and the addition of Co2 for my plants?

In a perfect setting, I would like to use my water as is without altering it's paramters, except with the occaisional de-chlor of coarse.

Any advice or knowledge is greatly needed.

 

[travis simonson]

You're on the right path. I have somewhat similar circumstances and use baking soda to buffer my water too. Just use enough baking soda to get your tank water to the 3-5 dKH range which is where you'll need it to be if you're going to supplement with CO2. Any lower and you can run into some wild pH fluctuations. Plants will do great at 3-5 dKH and your fish won't mind it all. You'll have to buffer the water at every water change, but I've found that this isn't really much of a chore. Good luck and let us know if you've got any other questions

 

[hashbaz]

Chuck Gadd (a respected name in planted tanks) says that the idea that CO2 and low KH will cause PH swings is wrong. In which case you have nothing to worry about. http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm

Can anyone confirm or deny this claim?