I see some posts where people are told that they tape over their heat tape too much with foil tape, covering too much, and that the foil tape reflects the heat down, so that more heats up the tape itself and less gets to the tub.

So I was thinking. What if I lay down a layer of foil tape ON THE SHELF first, before putting the heat tape on top of the foil? That way, more heat will be reflected UPWARDS towards the tubs, and the heat tape won't have to run as hot to achieve the same temperature?

I got this idea because I saw some heat mats available where they include a special bag to put over it, the top being transparent material, and the bottom being aluminium, so as to direct the heat upwards towards the tank/tub.

What are your thoughts?

Also, for those of you who put the tub directly on the heat tape, when you guys say you have your tubs "touching" the flexwatt, do your tubs have raised edges or little bumps on the corners? Is the tub really "Sandwiching" the flexwatt onto the shelf with no air space? I have these tubs that have a tiny little raised edge that goes all around (not bumps or legs, like a ridge that goes around the whole bottom side), that is probably half a mm thick. Since there will be water bowls etc. in the middle weighing down I bet the middle will have some parts touching the tape too. Is this OK?