"Pelvis Popcan" wrote in message
...

Water-holding polymer gel has received much attention, but its use is
controversial. In isolation, polymer gel crystals can absorb a lot of
moisture, expanding up to 100 times their weight in distilled water.
In soil, however, ions decrease the water-holding capacity of polymer
gel by as much as 85%. Research shows that at the low rates
recommended on product labels and offered in some potting mixes,
polymer gel is ineffective in increasing the water available to roots.
Organic matter is less expensive, so it can be used in potting mix in
much greater quantities than polymer gel to hold far more available
water. To be effective, polymer gel must be mixed into potting soil at
such high volumes that its expense and excessive shrinkage preclude
its use."

In searching the web, I can't find anything to corroborate these
statements.

As a chemist, I would tend to believe this. But, still holding up to 15X
their weight in water might be helpful.
I grow my tomatos in pots with mixtures of potting soil and top soil (cheap
stuff) and need to water like crazy.
Frank