"Haywire" wrote in message
ble.rogers.com...
The laterite is an iron/aluminium rich clay. although granular it will
dissolve in water. I laid my laterite on the bottom of the tank then
covered it with 1/8" gravel.

Laterite will not dissolve in water. Anything than might dissolve would have
been leached out of the material long ago. Laterite is a highly weathered,
tropical soil which has had everything soluable leached out of it over
thousands of years due to natural weathering. Iron and aluminium are pretty
much all that is left.

It will mix with water, to form a "mud", but it doesn't dissolve.

James Purchase
Toronto