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I just learned something today after struggling and searching for a few days. I thought this info may help someone. I replaced my Pentair Mastertemp 250HD with a slightly used ($1500) Pentair Mastertemp 400HD model 461021 ASTM, an exact fit so it would be an easy install. However. I could not...

It seems as though, every time I replace our pool pump, I have to glue new couplings onto the fixed piping - because the old couplings are different from the new. Can anyone tell me: what different sizes are in common use, or being sold in the US? if there are other threads in common use, or...