There is no way to permanently remove metals from water unless you use a DI or RO unit. Any product that claims as such is spewing blargh.
KH is a measure of the carbonite hardness of your water. It's the KH that keeps your pH stable.
GH is the general hardness of your water. A high GH can reflect a high TDS content, so some people use GH as a measure of how "thick" their water is.
The only number you need to be concerned, insofar as your fish go, is the GH.
Seriously stop worrying and don't add chemicals to the water. Everytime you put something in the water you usually end up raising the GH. That's not what you want to do.
It is my understanding that GH and KH are both some measure of "dissolved solids." So it seems logical to me that the only way these dissolved solids could increase in aquarium water is if something was leaking minerals into your tank (bad substrate, rocks, etc).
No, not quite.
Is this correct? One thread had an aquarists TDS seemingly rising on it's own w/no offending aquarium decor. And it would go down when he did a water change.
TDS is a natural occurence in the aquarium. Everything gives off waste: your fish, the bacteria, dead plants, what have you -- everything adds to the TDS over time. As with nitrates, the only way to remove TDS is by doing regular water changes. Water changes aren't just for removing nitrates, it's for removing *all* that stuff.
Seriously, if you are that worried that your water is too hard for the fish, get a GH/KH kit and test it. Then we can make recommendations on what you can do from there. Otherwise you're just running in circles and getting dizzy
Roan
