a good welllll established pod population would have helped, which could be had in a dsb or with plenty of lr, an da detrivore kit, but now is not a good time to add them, chances are tthey would get eaten before they could do a thing, and yes, lawnmowers only eat algae, no tdetritus, maybe some crabs and or shrimp, but they too may have a prob with the puffer being in there
best i can reccomend off the top of my head, is add some lr(well cured), the pods on it may survive, being as tehy would hav cover and shelter from the start, but adding them any other way, they would probably get eaten before they could get shelter
HTH