With a range of voltages this can become a little confusing when selecting your tank.
The 12v and 24v pumps tend to be used when mains power isn't available - an example of this will be farmers filling remotely in fields oppose to having to come back to the farm.
A 230v which is the most popular choice with our customers is a mains powered option and will work on a standard 3 pin UK plug. This option is mainly chosen with people who have constant access to power sockets.
The 400v option goes more into 3 phase which we suggest speaking to a qualified electrician to see if this is the voltage you require.