That is dissapointing that you did not have either the right size Chlorine generator or incorrect instructions on how to use it.
Firstly there should be no shortcuts on using the filtration pump, you need to get 2~3 changes of water a day through the filter which is a lot of water and takes time to get it through the system.
The water is hard in Spain but maintaining the pH between 7.2~7.4 will virtually illiminate the effect of calcium build-up in the pool and would have made the saltwater system 3 times as effective.
Using multi-chemical tablets is really not that easy, you see they contain chemicals that saturate the pool and slow down the action of any Chlorine in the pool you need to test for Chlorine Stabiliser – Cyanuric Acid –
This should be at a level around 40ppm, at 100 ppm in the USA a public pool would be considered unsanitary and closed until the water was emptied and refillled. In Spain not many people bother about swimming pools and sanitising them correctly – with your saltwater system you would have known exactly what chemicals are in your pool and only need to add a couple of bags of salt a year and maintain the pH + a cupful of stabiliser if needed.
If you need any help or advice we are pleased to help.