Just a few clarifications...
badflash wrote:From my experience (limited I admit) if you add soft acidic water to hard basic water you get.....Hard basic water.
Well, it all depends on how much soft, acidic water you add. Either way, the "hardness" (I prefer to use conductivity) of the water will be reduced. The ph might or might not be reduced depending on how acidic the new water was. The ph will be buffered by the *carbonates* and will resist change. So, you might actually end up with soft or medium hard alkaline water. Alkaline does not always indicate hard water. I, for example, have very soft, neutral to alkaline water coming out of the tap, but I make it more alkaline for my Neocaridinas and various other shrimp.
If you water is soft naturally, it tends to be acidic.
Yes, but only if your water is coming directly from the soft, acidic river to your tap.

In all other cases, your city adds something like sodium hydroxide to raise the ph above 7.
If your water is buffered with calcium, when the acid tries to work it just reacts and fizzes out some co2. Nothing much else happens.
Calcium has nothing to do with ph buffering. It's the carbonates and bicarbonates (and a few less important alkaline builders). Calcium only contributes to gh, whereas carbonates contribute to kh. You probably got confused because crushed coral is calcium carbonate and you thought it's the calcium that causes the ph increase. It's the carbonate.
Once I acclimate the bacteria to a certain pH it seems to hold on its own. I guess this is bacterial selective breeding, but it works for me.
Nah...the bacteria have nothing to do with the fact that your ph stabilizes to a certain value after some time of adding acid. The reason your ph goes down a lot in the beginning and keeps coming back is because the initial addition of acid produces a lot of hydrogen ions, which push the ph down right away. The alkalinity builders in your water (carbonates, hydroxide etc.) take some time to counteract and cancel out the ph change (hence they "buffer"). However, ever time you add more acid, the less the alkalinity builders are able to do that. So, every time the ph bounces back to a slightly lower value. The bacteria are not affected by this and have nothing to do with ph or conductivity.
Hope this clarifies things.