The fluid pH can be controlled with caustic soda, KOH, soda ash or magnesium oxide. The pH is generally maintained around 9.Fluids have been used with and without bridging agents. The presence of bridging agents increases pump pressure and therefore limits the length and diameter of coiled tubing that can be used on a well. Short coils with adequate diameter can use bridging agents in the fluid. However, when the measured depths are great and the diameter is small, bridging agents can not be used. For example, tubing with a 2-in. diameter and a length of 15,000 ft, could not stand the pressure created with the use of bridging agents.