06-14-2005, 09:02 PM
Join Date: Apr 2006
If your tank has been set up for 4 years, there may well be enough mulm (gunk) in between the gravel, to serve as the equivalent of a soil substrate. You might be better to stick to plants that take nutrients from the water column more than the roots.
However, if you still feel the need to put some sort of additional substrate under the gravel, be very careful.
Stirring up all the toxins that accumulate in a substrate over time can be LETHAL to fish. If you are going to do this, i would consider moving all your fish to a holding tank, drain and keep about half the water, before stirring up the gravel. Take the gravel out, add whatever you want to add, then put the gravel back.
Add the water you saved, fill the tank, add the plants or whatever and let it sit for a week or so. Only when things are settled (invisibly as well as visibly) you can add the fish. You would be well advised not to change the filter medium at this point, as it is full of vital bacteria which will help detoxify the toxins you stir up.
hope this helps.
ps.. i have killed fish stirring up the gravel to do this before, so i KNOW its real!!