Did a massive rebuild of this tank several months ago. The cobalts have been happy and healthy for months!
I know Im extremely late onto this particular scene but charcoal in the substrate like that which is provided through ABG mix would definitely help, if your running a water feature mKe sure you can access it readily, for me this is a false wall in an 18x18x24 exo, more to come, and I. No expert but have went through the "cycling" of fish tanks often and imagine its a similar bio process, with my tanks, fish lizard and now frog I insist on getting everything right BEFORE putting animals into it! Are you using springtails and isopods? unless you post pics of your setup and specs nobody can truly help you, if your new look on the help topics forums, i have multiple tanks and no frogs, would rather make sure the tanks are perfect now and succeed later with frogs, my trial tanks will help me establish a larger tank down the road, go big or go home, but make sure you do it right the first time! and my other tanks will serve as quarantines and supplemental tanks lolMy setup has a slight natural gas smell to it. the tank has a water feature that runs over some wood. Is this something that should concern me?