I had that happen with Tatanka relatively frequently but my overflow box in that tank is shallow and I have a screen on the bulkheads . The one in the link is threaded for an internally threaded bulkhead but there is also a slip screen if yours are smooth. In another tank (currently with Shiitake), I keep a light over the overflow box because there is only one bulkhead and any type of restrictor will cause a tank overflow. If she has found this nice dark place once, she will find it again ...