The PVC X cross "arms" are a very good idea when using a bucket to hold a diffuser. Buckets even with additional ballast weight often tend to tip over due to uneven pond bottom, sloping bottom contours, unevenness of overlying organic sediments AND the tugging or resistence of the incoming airline.
Sometimes the "fluffy" loose unconsolidated organic sediments on a mature pond bottom are 18" to 3 ft thick.
