Is Using Calgon Expensive?

Good afternoon all. This is my first post and I was moved to join this forum having read an article about the pros and cons of adding limescale prevention powders or tablets to a machine. There seems to be some debate as to the benefits or not of adding these products so I did a little research and a bit of maths and, for me, concluded that adding limescale prevention was simply not worth it. The figures are as follows and are based on the current costs from Asda and on my living in an area with very hard water (according to my water company Anglia Water) I've chosen Calgon since it's all that Asda sell.

With Calgon: Calgon tablets: 32p each, Asda wash gel amount recommended for soft water: 8p per wash So total per wash: 40p

Without Calgon: Using amount of gel recommended for very hard water: 14p per wash.

Saving per wash: 26p

We are a family of 5 and do, on average, 15x5kg washes per week. That's 1560 washes during the life of my current machine (2yrs) With calgon that is 1560x40p= £624 Without Calgon that's 1560x14p=£218.40

This means a saving of £405.60 in two years (or £202.80 a year) if Calgon not used.

That saving means I could buy a new washing machine every year and spend the same amount if I chose to. In reality, my machine has lasted two years so far and shows no signs of faltering. If I felt strongly about the ecological aspects of replacing a machine every year, I can have a new element fitted annually for £75 or fit it myself for £16.25.

The stark conclusion is limescale prevention is a complete waste of money! So thank you Washerhelp for waking me from my ignorance and saving me a packet.