If during descent the diver experiences repeated breathing resistance, and is forced to perform a by-pass because the bellows are at the bottom, the hydrostatic valve has probably malfunctioned. Diving can continue when the hydrostatic valve does not significantly affect diving safety. If the breathing bellows continue to move to the bottom, although no change in depth is made, this indicates leakage from the breathing circuit. The diver should then immediately abort the dive and return to the surface.