What is the easiest way to convert substrate?

[BushFishRox]

thanks...

so I will need about 150lbs for around 2"s I have 150lbs of gravel in there now for about 4"

 

[fish head )'>]

Try to keep as much of the existing water to refill the tank. The last amount of the water left in the tank as you are emptying look nasty. -get rid of it. consider doing the change with a dirty filter. (Right before you would normally do maintenance.) Since you are getting rid of all the gunk in the substraight, which is part of the cycle chain, your dirty filter may help avoid any spikes.