Pictures look great. I am just returning to the hobby and I really can't give you any reef advice. My tank isn't setup but hope to have it ready in a week or so. I can offer some ideas on taking photos as this is my other interest. I am a Canon guy and currently use a Canon 1DMk3. First your images look great, color and composition are excellent. Shooting into a tank is new to me so I am going to have to experiment myself.
I did copy over one of your photos and looked at the EXIF and noticed you are shooting at ISO 400, F5.6 and 1/40 second. Here are some things I would do:
Use a tripod, a must to eliminate the camera shake and because you are going to have to balance between lower shutter speeds and depth of field. If you are using an image stabilizing lens on a tripod, turn it off, you don't need it on.
I would also increase the ISO to 800 and the corresponding shutter speed will be about 1/100 and the F/Stop will be F8.0. This gives a sharper image and increases the depth of field (more in focus front to back). You can try going to ISO 1600, two stop gain so your shutter speed is up to 1/250 and f/stop is F16. I don't think you need to go to f16 so keep it at f/8.0 and increase the shutter speed to 1/500 second.
Another thought is to stop the water motion when you take the photo, this way you don't need to go up to 1/500.
Going up in ISO will also increase the noise of the photo. You can't avoid this unless you want to spend more for your camera. Or, just wait, prices for the high end features are always coming down and will be available for everyone sooner or later.
To get around the noise, you can get a third party software like Noise Ninja, download it, try it and be amazed in how well it can reduce the amount of noise in the image. I use this all of the time in my post processing.
Sorry for the off topic response, I know this isn't about taking photos....
Ron