The 1 1/2" coarse thread is one of the most commonly used threads (for example Pleatco PWW50P3) for hot tub filter
It occurs, for example, with the following filter types: Unicel 6CH-940, Pleatco PWW50P3, PWW50-P3, Filbur FC-0359, Waterway Plastics 817-0050, 25252, 378902, 03FIL1400
It is used by many small to medium hot tub manufacturers. The very large manufacturers have all switched to 2" connections or fine threads.
Why is that?
Due to the small diameter (approx. 46mm) and the filter diameter (most are about 150mm), a very high torque is generated on the thread. This can cause it to be tightened very firmly without realizing it. The high feed of the coarse thread creates a strong pull on the thread. This makes these small diameters very susceptible to breaking off. This can happen with cartridge filters just as it can with Ego3 filters.
Sometimes it is enough that the material becomes a bit more brittle over time due to too much chlorine, causing it to tear because it was previously tightened too much and/or the temperature is lowered, the plastic contracts, the tension increases even more, and the thread breaks off.
hot tub Guru Tip: DreTighten the thread firmly and then turn it back 1-2 cm. This way, the thread can never break off.
The Ego3 Set 2 replaces your old cartridge filter with 1 1/2" coarse thread and, for example, the following cartridge filters: Unicel 6CH-940,
Pleatco PWW50P3, PWW50-P3, Filbur FC-0359, Waterway Plastics 817-0050, 25252, 378902, 03FIL1400,
Magnum WY45