Bulkhead washers allow you to really tighten up the bulkhead on a broader base, and apply glue under these washers to create a diehard seal. Okay, bulheads are nice, but what if you wanted to silicone them? What if there was a slight irregularity in the side of the pond or tank which needed to be accomodated, or glued, or both? What if you wanted a much larger "grab" on the bulkhead? Simple. Use these bulkhead washers when you want a wider "grab" on the liner, and when you want to silicone glue your bulkheads in place. It's an extra level of insurance. When deploying our bulkheads through glass, there's no need for these washers.
How do you size them? Well, it's confusing because at SuburbanPonds, you buy the actual bulkhead based on the INTERNAL diameter you want. But the bulkhead washers are simply sized to the bulkhead you've ordered. If you've bought our two inch bulkhead, you need the two inch washer. Three inch bulkhead takes the three inch bulkhead washers. The washers are sold in, and supplied in pairs.