Is a W3T-CELL-15 the same cell as a T-CELL-15?
On the listings here, yes. Each original Hayward cell gives its older name beside the current one: W3T-CELL-15 is also shown as T-CELL-15, W3T-CELL-3 as T-CELL-3, and W3GLX-CELL-5 as GLX-CELL-5, the cell that takes over from the Goldline T-CELL-5. So search by either form and you reach the same product. What decides the fit is the number at the end, which is the size: 15 for pools up to 40,000 gallons, 9 for 25,000, 5 for 20,000 and 3 for 15,000.
Will a CompuPool or CaliMar cell run on a Hayward AquaRite?
They are built to, and each one says which Hayward cell it stands in for: T-Cell-15, T-Cell-9, T-Cell-5 or T-Cell-3. Their system rows list AquaRite, AquaRite Pro, AquaLogic and ProLogic. The CompuPool cells come with the cord and a clear housing, so the plates can be looked at without unplumbing anything. One row deserves a careful read: several of these cells state the age of system they suit, some after 2009 and one before, so check that against your power center before you choose.
Does a Hayward TurboCell come with unions?
Not the originals on this page. The T-Cell-3 is described as the cell only with union nuts not included, and the T-Cell-9 says the same about unions, so the usual plan is to keep the pair already on the pipe. What the original does bring is its cord: the T-Cell-15, T-Cell-9 and T-Cell-3 each list a 15 ft cell cord. If the old unions are cracked or the o-rings have gone flat, replace those separately at the same time rather than finding out on the day.
Which Hayward cell is for an above ground pool?
The AquaTrol cell. AquaTrol is Hayward's above ground system and its cell is the GLX-CELL-5, sold here as W3GLX-CELL-5 with a 15 ft cord and a 20,000 gallon rating. Its listing says it replaces the Goldline T-CELL-5 and also the Mineral Springs MS-20 and MS-21 cells, and notes that it is used on inground pools as well. The T-Cell-15, T-Cell-9 and T-Cell-3 are the AquaRite cells.