IMO, anything you have to buy is a waste..... ;o) Big rocks within a basket
are the easiest way to go, though I would not do Lilies like that.... but
then I've also moved all most all lilies to a lily pond, as my koi ponds
are too shady. I do have 2 lilies that do fine in the shade and they will
stay put with the koi. For the most part they have sandy soil to dig their
roots into, but the hard round rhizome part has big rocks on it. ~ jan

See my ponds and filter design:
http://users.owt.com/jjspond/

~Keep 'em Wet!~
Tri-Cities WA Zone 7a
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