Does it matter if my laterite and gravel is mixed together or does it have
to sit under a layer of sand?

Laterite IMO works best when mixed with a little gravel or sand. It is
not necesary to put sand over it, but it may help keep the cloudiness
down a bit initially if you do. Sand is not the best substrate
material for planted aquariums though unless it is a coarse sand of
arounf 2-3 mm.

In article alttf.17189$6K2.950@edtnps90, GS wrote:
Does it matter if my laterite and gravel is mixed together or does it have
to sit under a layer of sand?

It says right on the bag you can mix it and even a little bit goes a long way.

Or it used to anyway.

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