After troubles with store brought backings, eg. dull taped on look, lifting Seaview product after a little over one month, I was a little disheartened but didn't want to paint either...
I came up with the idea of using Signwriters Vinyl. Cost $25 for 1.5 metres. If you choose this option, lift backing paper instore to ensure colour is on sticky side too, some vinyl's are white backed (colour won't be on sticky side which is what finally shows through the glass). Apply wet with water/dishwash solution, start in middle of tank and work out bubbles to the edges with credit card or similar. Easy! Is similar idea to the Seaview but actually sticks to glass and won't lift if water drips down back of tank or heater lifts big bubbles like mine did. It should last many years, or until change of mind, most vinyls are 5-10year rated for outdoor & vehicle use.
I wanted a blue background and chose the slightly more expensive metellic look. It changes colours depending on angle viewed at and available light reflections, pictures below (YES it IS the same tank). Please excuse third one, couldn't focus close without flash. I'm extremely happy with the final product! What do you think?