I'm going down to Balito area. And I do have 2 plastic drums with tight closing lids of 90 liters each. I'm thinking of collecting both drums full sea sand with enough water to cover the sand inside. Will be done either the morning before we drove back or the previous evening. Then all the way back to Pretoria. Should be enough for a 1.5m by 600mm tank. The substrate I have now is crushed coral stuff, very ruff and coarse. I want to take all of this out and replace it with the new, hopefully still fresh sea sand. Now my questions. Do I have to cycle the tank again, I will not replace the water? (maybe 20 to 40L) What about the current livestock I have in there? How much die-off can I expect, or should it be OK? Must I seed this sand? Put some of the old substrate in stockings and let it lie halve buried at the bottom. SO that the micro stuff can migrate, and I can get the ruff stuff out easily. I do not think I have to wash the new sand, as that will remove any life that is still around. Anybody else done this? Is it a worthwhile exorcize?