Ok. So I tested my KH and GH in my 60. I recently lost two cardinals ( had for 8 months) 1 neon (6mo) and two new neons. All the rest of the fish are fine. (Zebras, yoyos, guppies, white clouds, cherry barbs and rummynose).
My KH is a 4.5. Which is great for my plants and tropical community...