The problem of a DSB is once the anaerobic bacteria are released they instantly die off and pollute the tank with toxins. Release of the anaerobic happens when stirred up, or they reach an age or degree of becoming stagnated (the old tank syndrome). It’s not a nutrient release that creates the instant tank death although it can contribute to the ill effects of old tank syndrome as can any stagnated bacteria havens like the old wet/dry’s.
When your “in tank” DSB is stagnated you essentially have to replace (or somehow clean) it, or, suffer through the ongoing consequences.
Alternates to using a DSB:
1) Remote DSB so it can be replaced or cleaned without releasing toxins to the tank
2) Provide more, and/or more dense live rock to harbor the anaerobic bacteria.
3) Carbon dose, or now the use of Bio pellets to supplement the aerobic bacteria to increase population sizes to be able to consume the nitrates along with the supplemental carbon source (to me this is like bacteria on steroids)
4) Nitrate reactors
This is from DR.