Setting up an old 4ft tank for winter in the sunniest corner of the yard.
Just to grow out plants (like Corkscrew Vallis, Amazon swords, maybe a few crypts and some natives from the pond ) under natural sun, with glass lids to keep the warmth in. Not going to be running any filters or air and will regularly fertilise with LeafZone or similar.
Wasn't really intending to put any fish in, but might catch a few of the guppies I put in the pond over summer that the frogs didn't get to see how they go.
Planning on using about ½ - 1 inch (that's 10-25mm) bentonite clay as the bottom layer and a thin layer of river sand then about 1-1½ inch of washed river gravel on top.
Should I be putting anything else between the bentonite and the gravel? Potting mix (tho' I'm struggling to find one without additives) or some sort of mulch for example?