Angela_96

Okay so I am a Resp theraipist.. literally a pH geru...

Now... we draw abgs and the normal human ph is 7.35... anything above is alkiline and below is acid....

When we check our tanks... we look for certain levels also and for my african cichlids they like the water 7.8 +. which is alkiline water. For SAmerican fish they like Acidic water... below 7.0.
Why do they have a sep test for alkilinity as well as the ph? its the same thing, right? I am just not understanding why they have the sep test.

Butterfly

alkalinity is not the same as pH because water does not have to be strongly basic (high pH) to have high alkalinity.
Alkalinity is related to the amount of dissolved calcium, magnesium, and other compounds in the water and as such, alkalinity tends to be higher in "harder" water. Alkalinity is naturally decreased over time through bacterial action which produces acidic compounds that combine with and reduce the alkalinity components. quoted from http://www.koiscapes.com/subcat328.html

I would guess that you need the separate alkalinity test to see how high the Ca, Mg, and other compound concentrations are in your water.

Hope that helps.
Carol

sirdarksol

See, here's what happened: Three different scientists decided at different times that they wanted to use the term alkaline.
One decided that it would involve pH (acidity vs alkalinity).
Another decided it would involve the layer of minerals that buffer pH (what we talk about in aquaria. A high alkalinity usually means a higher pH, but not always, and it protects the water against sudden pH drop due to waste/plant breakdown).
Yet a third decided it would be used to refer to certain extremely heavy metals and salts (some of which are involved in the second alkalinity).

The end result is that we use the term for three different yet related concepts, which is utterly confusing unless you have a degree in chemistry, apparently.