Pls. advise. Currently thinking of mixing Flourite w/ my plain old gravel (contains 55oz. of Laterite added a few months back). Is this a good idea? Or you I just add more Laterite since they can be mixed in w/ the gravel? Originally planning on taking out the old gravel & replacing w/ Flourite but afraid of the mess its going to make, not to mention all the good bacteria I will be taking out. Also don't have any clue how to do a gravel swap. Any advise will be greatly appreciated. Thanks.