Custom Masters/Flo King
Phone: 407-331-4634
Fax: 407-331-0575



• Filter cartridges that are too tight for the application (too low of a micron rating) can cause pump cavitation, aeration and foaming. Low-micron cartridges can starve the pump intake and clog prematurely. In these cases, try a coarser filter cartridge (higher micron rating).

• Make sure solution is sufficiently above the "Weep Hole" on the pump body. Solution must be at least 0.5 inch (1.27 cm) above the weep hole on the Lab Series, 1 inch (2.54 cm) above the weep hole on the BX650 and BX1200, 3 inches (7.62 cm) above the weep hole on the BX3000 and BXL2500, and 4 inches (10 cm) above the weep hole on the BX5000 and BXL5000.

As depicted in the illustration below, the impeller is spinning just beneath the Weep Hole and must be submerged in solution for proper priming and to prevent aeration and turbulence at the solution surface.


• If this is not a new pump and has operated satisfactorily for a while, the internal Super Slinger may have moved or become distorted over time. The purpose of the Super Slinger is to keep solution flowing out the pump Discharge Port instead of up the pump body. See these links for photos of the Super Slinger and other parts for all Flo King pump models.

slinger on bx3000

• Some solutions are extremely air sensitive, containing wetting agents or other ingredients that are more likely to foam. In these cases, solution movement should be mild, rather than moderate or aggressive.

• It may be desirable to install a smaller pump with a lower flow rate in air-sensitive foaming solutions.

It may be necessary to isolate the problem by trying each of the following to see if the aeration is reduced or abated:

• Run the pump with new, clean filter cartridges attached.

• Run the pump without any filter cartridges attached.

• Run the pump with coarser filter cartridges attached (higher micron rating).

• If you are using the pump with the Slide-In Filter Cartridge Adapter (SIFCA) accessory, read section below.

The Slide-In Filter Cartridge Adapter (SIFCA) is an accessory that allows you to change filter cartridges without moving the pump from the tank.

sifca drawing

The most common cause of foaming when using this accessory is failure to lift the O-ring to bleed air from the SIFCA.

Each time you install the SIFCA and filter cartridges onto the pump and before you turn on the pump motor, use your thumb to pull the O-Ring toward you. This will reveal a small hole from which air will escape. You will hear a hissing sound as the air leaves the SIFCA piping.

Once the air has been purged from the SIFCA, turn on the pump motor.

See this link for SIFCA Operating Instructions.

If you are correctly using the O-ring but still experiencing foaming, try using the pump with filter cartridges attached but without SIFCA. If the pump continues to aerate the solution, you may have a pump problem or a filter cartridge problem, rather than a SIFCA problem.

In these cases, refer to section above entitled "Troubleshooting Steps for Foaming."