Not familiar with Gimp but if you're converting your picture to jpeg and then processing it with Gimp then you're loosing he advantage of raw. You want to do your white balance and exposure correction at least, while pic is still in raw. Raw allows you to better correct colors hints than jpeg allows, instead of relying on camera to make choices for you ots best to make those choices yourself in a raw editor . This is more critical in aquarium photography than it is in other types of photography as we shoot jnder high kelvin rating and the camera is easily fooled by that , as well as camera not really knowing what effect or final color unwant in your picture. For other steps of editing like cropping, cleaning imperfections or deleting parts of thenkmage like microtubules or algae.... its basically the same whether you do those in a raw or a jpeg editor. If u find a raw editor that does everything for you then that's one step less in your postproceddung workflow.
I use Adobe camera raw to correct exposure and white balance of my raw pictures and do needed cropping then convert to jpeg and delete the raw files. Then if picture is to be printed or posted online I open it in photoshop to do some cloning or other steps to cleanup the image then fine tune colors or exposure if needed, add some sharpening, resize if needed and save. Adobe light room I believe will allow more of both editors in one go but am not familiar with it.
