It's a practice, practice, practice kinda thing. There's all kinds of stuff to be learned along the way.
One thing you can try is to place something white (piece of PVC) in the tank just out of the frame of where you want to shoot, take a picture of that, apply white balance settings to correct the color temp and then apply those settings to your actual images, course you can only do that if your software allows you to save the settings or at least view the kelvin temp.
I actually use a plastic 'gray card' and can set a custom white balance from inside the tank. It makes processing so much easier and cleaner, course I'm an old school film guy.
Look forward to seeing more of your images.