Is it ok to use an aquarium tank as a vivarium? I ask because Petco is having the dollar a gallon sale Sunday and this would be a good opportunity to upgrade Rex to a 40 gallon tank and make room for a future new addition. Only downside I see is that the top is not slide off or a nice front panel. But the price is a steal and appears to accomplish the same thing really. 40 bucks for a 40 gallon tank.....yea. So give me your thoughts on this please, always good advice goin around here.