The large hole or small hole rba makes no real difference in the Toptank. Both work fine and the tank can be drained with the small hole one just fine.
The 1/2 ML difference in fill is more than made up for with the ability to fill from the top vs the stm. The bubble glass available that fits makes the Toptank hold more than an STM if that is an issue.
The 1/2 ML difference in fill is more than made up for with the ability to fill from the top vs the stm. The bubble glass available that fits makes the Toptank hold more than an STM if that is an issue.