Salty Fishes said:
I'm pretty sure that the "pH Up" product is just sodium bicarbonate: or baking soda, just much more expensive because it has a fancy label, so yes, of course its safe.
The liquid pH Up products are not baking soda from what I can assume. But they are not good to use as they don't affect the buffer. Instead they just add acids or bases to your water which is just simply not a good thing to do. They also contain phosphates. That leads to algae.
If you are having a problem with pH (and by that I mean it's either frighteningly unstable or it's extremely high or low) then your best solutions are the sort that will be slow to act, but have long term effects.
To raise pH and keep it steady, you need to get more buffer into your water. There are many ways of doing this. One that I can think of offhand is to put a stocking full of crushed coral in your filter.
To lower it and keep it steady, you need to soften the water but also maintain a source of consistent stability. I do this with peat filtration on my blackwater tanks.
But I'm assuming that you're pretty much trying to bullseye a 7.0 pH. It's really not necessary, and in fact a good 70% of fish, in my estimation, actually prefer slightly acidic water anyway.