I've read that disturbing a DSB can be a toxic event. However fish such as jawfish are total earth movers. I have a 4" bed in my tank and have failed 2x with jawfish. I'm wondering if the fish is digging and poisoning itself. I've noticed high NO3 in the tank.

So how do I reconcile not disturbing the DSB with owning a digging fish that it's reccomended having a DSB for?

Having enough LR and and a decent skimmer to take care of any wastes thrown up by them, and to convert nitrogenous watses quickly. A large macro algea refugium probably wouldn't hurt eaither.

FWIW, check out my thread. 20g tank, 4 - 6" DSB, 2 jawfish. NO Nitrates and SPS growing nicely. I have no ieda how much LR I have (probably in the hood of 40lbs) and a refugium about 5g filled with chaeto, and fed pretty heavily. Coming up to one year in 1 month

the problem isnt detritus.
its the anoxic pockets that form in the sand. these are basically large concentrations of sulfuric gas which when released will mess up your water parameters. you quite frankly cannot do anything about a digging fish with a DSB. you should have researched what a DSB would do before you setup your tank. you also should have researched what a good environment for a jawfish is.

also you could build your own house for the jawfish so that it wont mess round with the sand.

hopefully. these don't always work as they sometime decide to just go make one of their own. on another note they do like barnacle shells as potential homes too