| | Re: Soil Depletion?
You don't necessarily need to tear it down and start over. You could increase the number of fish and feed them generously. This puts nutrients back into the system. Although the nutrients in the soil may have been used up, the soil still has the capacity (CEC) to sequester nutrients and hold them until plant roots can use them.
If you can't increase fish/feeding, you can dose fertilizers in the water column, as you would in a non-soil tank. The same thing will happen to those nutrients. And you can use plant tabs or other substrate fertilizers to increase nutrients in the depleted soil.