Take a look around and see if you can find 2-3mm coarse silica sand. That's an ideal inert substrate in my opinion and experience.
That used to be a reasonably easy find at dedicated aquarium shops. IMO not so easy to find nowadays. Pool filter sand is of similar size and it's uniform in dimension and a little easier to find at local hardware stores, pool supply places and garden centers. Smoother than BDBS for cories and such. Only potential drawback is that it is pretty white (but some like that)
I've used laterite in the past with good anecdotal results.
Hey Phil - hope all is well