Well, the 40 lb would fit under the stand, yet we have long drapes right beside the tand to conceal it. The 20 lb would probably fit I would think, and I really do not mind filling a couple times a year. The more I hide, the happier the wife. Plus the cost is much cheaper. I think I might go with the 20, I was just worried about how long it would last. Glad to hear info from someone with a fairly large tank. Thanks.