Hi Xavier 55,
It is a fairly easy process more time consuming than anything. You didn't mention your tank size but for me with a 55g I went and purchased a large Rubbermaid tub w/ Lid. After making sure it was clean / all holes sealed I cut a appropriate holes in lid for the filter and heater and then added some additional holes for air (I had fish that would jump) I then used my siphon to transfer the tank the water to tub roughly 75% and added a little stress coat. I just put the plants in buckets with the additional tank water, I used a old plastic scoop to remove the old substrate although I have read of people using shop vacs to complete this step even faster. After I cleaned the tank I added the new eco complete substrate and added about 25% water and let settle it over night the next day I transferred plants, water, fish in that order with no problems. You may want to separate the shrimp but I am not positive as I have never had shrimp.