Hi all, so I'm maintaining one of those hang-on-the-wall AquaVista 500R aquariums, and recently the bulb burnt out. No big deal, I replace it with another. When I returned in two weeks, it was out again. Hmm... dud bulb? I replace with my second spare. Same result. If the ballast is dead would this be the result? The bulbs did work when I first put them in, but I'm not sure how long they stayed lit before they too died. Thanks all!