So quite a while ago I had a pH crash due to low kH. I added crushed shells to my filter and floated cuttlefish bone in the tank and things were better. Then I got lazy testing kH... Recently re-checked it and it had dropped again to 4 drops with my API test kit. Added 2 new large handfuls of crushed shells to the filter and 10-14 days (with 1 or 2 water changes) later my kH is at 6 drops! Hooray! Just wanted to let you all know that it is possible to see improvement! There is hope! I feel like this has been coming up a lot recently... so I wanted to share. @AllieSten - I know this was an issue for you, but whom else?