buffering

[Briarmoor]

Why is my new tap water Total Alkalinity (KH) higher than my old tank water when both originally come from the same place? I tested both when I saw the old tank water was going down from about 100 to about 60. New tap water measured out 100. What is causing this? Should I be concerned? Can I raise it? Should I? I am doing 10% partial changes a couple of times a week.

Other levels in tank are:
Nitrate 40 (holding steady, but not coming down)
Nitrite 0
GH 100
pH 7.4-7.6

I have one live plant, flourescent lighting, colored rocks (heard this could affect a tank), resin tank decorations, artificial plants and a bubble wand.

P

 

[WILDER]

This article might answer some of your questions.
http/faq.thekrib.com/begin-chem.html

 

[sinistral]

I just have a minute to reply, but I would suggest that as long as the pH is remaining stable you not worry about it. kH is a measure of the buffering capacity of your tank, and is composed of carbon dioxide and carbonate ions. The natural trend of an aquarium because of the metabolic processes of fish is to become acidic over time. This "uses up" the buffering capacity of the water.

I'd have to look up and see how much CO2 diffusion out of the water can affect the kH in your specific case, and if one live plant (depending on plant species) could also contribute.

HTH~