For instance, {TAIL ~ hot tubs} and {HEAD ~ swimming pools} often maintain a constant circulation of water through a filter and heater assembly to clean and heat the water passing there through 
For instance , { TAIL ~ hot tubs } and { HEAD ~ swimming pools } often maintain a constant circulation of water through a filter and heater assembly to clean and heat the water passing there through
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH