Drilling tank

[pmcadams]

I have an external return pump so I need to buy a tank for a sump and drill a hole for a bulkhead on the end of the tank for my return pump pickup. Are most tanks with tempered glass tempered on the bottom only or all the way around?

[WhoDat?]

Most small tanks (less than 20 gallons) are not tempered at all.... the larger ones are mostly tempered on the bottom only.... however some are temered all the way around big and small... I've seen a few different ways of knowing if its tempered.... one way is looking through polarized sunglass at the tank while its outside .... if its tempered it will be many colors..... When I got my 20 gallon I just called the manufacturer to see if it was tempered before I drilled it.... It had no glass on the tank that was tempered....