The only burrowers I've got here are MTS. Other than the shrimp, all other inhabitants of this tank are snails.
I seriously doubt that CO2 was the culprit here. I've only got a single Hagen unit on this tank, and the CO2 levels never get high.
29g Eheim Classic 2213, community, heavily planted, 65W CF, 2x Hagen CO2
20g Fluval 3 Plus, nothin' but shrimp & snails, 65W CF, Hagen CO2