Humid air/ mould in the house, what do you do?

[TickToc]

In our last house I had Hippo Damp Rid crystal things in all the rooms & under the kitchen sink - the idea is they absorb the moisture from the air & after a few months all the crystals have liquified so you can tip them down the sink & refill,

[bbr]

In our last house I had Hippo Damp Rid crystal things in all the rooms & under the kitchen sink - the idea is they absorb the moisture from the air & after a few months all the crystals have liquified so you can tip them down the sink & refill,

where do you buy this? is it effective?