nappies used as water crystals.

Yep. Cheap nappies are on my shopping list! I watched the you tube video and was well impressed.

What an excellent idea!  I shall have to try this with the potting mix for my tomato plants. 

any of the disposable nappies. I bought 20 economy ones size 5  from T***o today. £1.40.

you can also buy adult ones which will give you a greater quantity of gell.

Don't know the truth about this but one comment on the video states:

The polymer used in diapers is generally an acrylic polymer that is not safe in soil or in soil water and some reports note that the compound is carcinogenic. The main problem however is that these polymers absorb water but do not release it to the plant. The plants in the photo are ok because they are living off the overflow water in the jar however as the plant grows, that water will dry up and the water in the polymer will stay in the polymer. Most plants need specifically engineered polymers that release the water to plants under osmotic pressure . They work long term but have to be applied correctly.

 
http://dif1-31.diply.com/videosworthsharing/he-pours-this-blue-liquid-on-a-diaper-reason/94755

Pip pip,
Balders

If they are carcinogenic, how come they can be used for babies. It does not sound as if they will hydrate the plants unless that is something that the plant gel makers have dreamed up to put us off.