Thanks for the reply. I'm a little confused though rpadgett37 as to why you bottom out the ph first then bring it up? I looked at Seachem Alkaline and it seems it's really similar to baking soda, but baking soda would be cheaper, no?
First I'll say that when trying to adjust PH, you need to focus on changing the KH of the water. Wherever KH goes, PH will follow. Not the other way around. Sorry for the confusion there.
To answer your question, because my starting KH value was so low and had no buffering capacity, and since my target PH was 6.8 from 7.6, there wasn't any choice but the drop the KH down and let the PH plummet with it. Under these circumstances, the only way to get to PH 6.8 with a strong KH buffering capacity was to go down, then bring it up again. As I mentioned, I use the Seachem acid and alkaline buffers for the task, and it is a personal preference for me. Baking Soda will do fine for raising your KH, but you have to watch it. I am not sure what to use to lower the KH.
How long does the baking soda, or any calcium bicarbonate hold up in water before I'd need to add more? I assume once stable, adding a bit each week would maintain this?
Not sure but it doesn't matter. Regular water changes will keep your KH reasonably stable provided you are doing all you need to in the aquarium.
NOTE: Your replacement water should have the same water parameters as what is in the aquarium, matched as closely as possible. If you are going to continue using baking soda or anything else, be sure to do it in the replacement bucket and not in the aquarium.
Another thought I have, would a ph controller for my co2 work better for me or would that not provide enough co2?
CO2 is another ball of wax, and there is no such thing as a PH controller for CO2. Basically, CO2 will always want to lower KH because of some chemistry going on in the water that I understand a bit but can't explain very well. Remember that where KH goes, PH will follow. The only thing you can control here is the amount of CO2 you are infusing into the tank. Fewer bps lessen the pressure on KH, while more bps increase the pressure on KH. The higher your KH when you start introducing CO2, the more stable your PH will be.
Here's a link to a series of articles that explain water chemistry better than I can. Lots of good stuff in here.
Hope this helps, and FY, snails and TOO MUCH Co2 don't mix. Snails do just fine with CO2 in the water. They aren't my specialty so I don't know if there are some snails more sensitive to it than others; however, I've never read anything that says CO2 is toxic to snails unless there is too much of it in the water. And finally, there is nothing wrong with adjusting your KH and PH values. Just don't do it in the aquarium with your critters. I always do mine in the replacement water prior to doing a water change.