The GH was up to 180 in my old tank today. Everything is still great in my new 5 gallon planted tank, though!What is the new hardness?
Pure baking soda should not affect GH. If you're worried about using off-the-shelf baking soda, you could pick up something like Seachem alkaline buffer to use instead, which will list the exact dosing to reach the desired KH. But wonder shells will have a negligible effect on KH, so I wouldn't expect much change there with continued use.
Thanks! When I added the baking soda the pH was 8+, and I couldn't get it down. KH and GH were also off the charts.