If you’re looking to buy a custom aquarium, there are lots of little things here and there that could seriously add to the cost of the setup. Things like black silicone, low lead glass, and other features certainly add to the bottom line, but there is one aspect that has a more significant cost impact. The size of the aquarium is the single biggest contributing factor to the price, and while it’s obvious that a 20 gallon tank will cost significantly less than a 100 gallon setup, the cost differences can still be drastically different between two similarly sized aquariums. And that cost factor is based heavily on the tank’s dimensions. Depending on the size and shape of an aquarium, the glass thickness could be 3/8″, which is pretty typical, or it might have to be bumped up to 1/2″ or 3/4″. If this occurs, you can expect the price to skyrocket. So, when planning that custom tank, get with the manufacturer to see what layout and configuration is the most cost effective.