Hi team, weekly test day. our established 250L fantasy bowfront still seems to have less than 5ppm nitrate. all other parameters are fine... except gH. (don't worry, we're cycled) so, pH is about 7.3 (slightly bluer than 7.2 but not as blue as 7.4). the kH turns light yellow at 3 drops so i'm calling that 3. I lost count on the gH after 10 drops. that's the highest our gH has been. we have oyster grit in the filter and a cuttlefishbone in the tank. i don't mind that level of mineral hardness, but it's just gone up a bit since last week and i'm curious as to what's causing it. I know it's "general hardness" for minerals, but our sources for an increase in this are limited. we have 0kH, 0gH rainwater. so we use equilibrium and buffers on new water. but we haven't done a pwc in a few weeks because the nitrates have been so low and the fish are happy as larry. (oops, i better not say that because we had a fish named larry that died...) but we have fine silica sand as about 40% of the substrate and smooth black gravel as the rest. all of our decorations are fake, and our plants are silk. our filter is sunsun 304B UV.