can you post some of your pics so that we can assess what's not working for you. As your mentioning macro mose i presume you are duffering with macro shots. I do not own your camera however general guidelines apply to all cameras: use tripod, shoot vertical to glass, use external flash if your camera can have one and have it angulated down preferrable off camera. use aperture mode if yuor camera has it to achieve required depth of field. try to use camera timer to minimize blurr due to motion while pressing the shutter. Clean glass one day before shooting and stop water circulation inside the tank while taking your shots, try different white balance settings, most frequently automatic or cloudy will work best. after you master all the above you could experimment with custom white balance measurment...
correct any of the above that you are doing wrong and post some of your pictures.