I just used carbon as my normal routine. The carbonated filter cartridges I use in my HOBs are cheap and I was buying them 48 at a time. For a really long time things were going well and I saw no reason not to use carbon, I use it in all my other tanks also. Everything was going along fine in the discus tank so you know the old saying "if its not broke, don't fix it" Fast forward to 6 months ago (ish) and I started noticing the pits, started researching and reaching out to Al. My first step was to up my waterchanges, I never missed a day, did two daily water changes some times on the weekend, then I decided why not remove the carbon it cant hurt. That's when I started noticing the pits looking better on a few fish, then they spawned so I am pretty sure its helping. Now I have ordered the calcium per Al's suggestion to replenish the water with what the fish may need to fully recover.