I was under the impression white vinegar & warm water every week (depending on your area/hard, soft water) is the recommendation?
I buy a big 5 litre bottle of white vinegar from Amazon and tip a capful of that with some warm water and run a cycle , then give it a clean and wipe. I do this once a week xx
But when it had some build up I just used a bit more white vinegar then I normally do and it got rid of it straight away xx
I use vinegar for descaling and it works super well
The Tommee Tippee Steam Steriliser doesn’t need descaling tablets.