I am upgrading a 30 long to a 40 gal acrylic tank . The 30 has been going for a couple of years . It has BDBS for substrate and is heavily planted . Low tech with Java Ferns, Crypts, Water Sprite,Pogostemon Stellatus Octopus, and some stem plants I can't recall the name of . I am going to use the same BDBS and add some for the 40 . My question is , if I rinse the old BDBS to get some of the detritus and mulm out will it kill enough beneficial bacteria to cause a problem ? I run a Marinland Magnum 220 canister and am going to switch it to new tank as well . The filter is very well established so I think with that and all the plants I will be fine . Just wanted to see if anyone else has done this and what was the outcome . TIA .