Just to warn those who might be considering the Seios as a means to induce lots of current with little power: I bought three 820s myself. All of them jammed with calcium build up in a matter of eight weeks. I cleaned them the first time without trouble, but they bound again (and worse) in a matter of a few weeks. Now in my tank I use a lot of kalkwasser for induced evaporative loss (3 gallons a day for a 120 to cool the tank), so I forgive all pumps and power heads for jamming to some degree (although these were far worse than the Maxijets they replaced in this regard). However, there is something far, far worse about the Seios than just jamming.
The problem is in the ceramic shaft and glide washers through which the shaft glides. Their shaft is made of ceramic and is therefore extremely easy to break during cleaning. Since cleaning a jammed powerhead or Seio almost always involves freeing the shaft with vinegar or muratic acid and using some degree of force, it is almost impossible to clean them without breaking the shaft. Furthermore the washers on which the ceramic shaft glides are also made of ceramic, and two ceramic surfaces very close can weld together very easily with calcium (calcium loves to bind to ceramic). The weld can become very strong too since the Seio CAN work with these two parts bound for days. What essentially happens is that the shaft and the magnet rotate as one, and then shaft ends rotate, with considerable friction, in the shaft end shoes. This is not a stable or efficient operating mode, though, and sooner or later, the pump will stop completely once the shoes also bind. With the shaft bound to its ceramic glide washers, there is no way to get acid to work in to the near microscopic gap filled with calcium between the ceramic washer and the shaft. Soaking it free is your only option (forget freeing it with force as that will just shatter the shaft), and even soaking might take days to work.
Essentially, these pumps are poorly designed since they cannot cleaned without breaking the ceramic shaft and are designed in such a way as to encourage jamming up. These pumps should be avoided at all costs if you have a high calcium tank, like those required for a high growth SPS tank.
The problem is in the ceramic shaft and glide washers through which the shaft glides. Their shaft is made of ceramic and is therefore extremely easy to break during cleaning. Since cleaning a jammed powerhead or Seio almost always involves freeing the shaft with vinegar or muratic acid and using some degree of force, it is almost impossible to clean them without breaking the shaft. Furthermore the washers on which the ceramic shaft glides are also made of ceramic, and two ceramic surfaces very close can weld together very easily with calcium (calcium loves to bind to ceramic). The weld can become very strong too since the Seio CAN work with these two parts bound for days. What essentially happens is that the shaft and the magnet rotate as one, and then shaft ends rotate, with considerable friction, in the shaft end shoes. This is not a stable or efficient operating mode, though, and sooner or later, the pump will stop completely once the shoes also bind. With the shaft bound to its ceramic glide washers, there is no way to get acid to work in to the near microscopic gap filled with calcium between the ceramic washer and the shaft. Soaking it free is your only option (forget freeing it with force as that will just shatter the shaft), and even soaking might take days to work.
Essentially, these pumps are poorly designed since they cannot cleaned without breaking the ceramic shaft and are designed in such a way as to encourage jamming up. These pumps should be avoided at all costs if you have a high calcium tank, like those required for a high growth SPS tank.
) but the volume that it cycles stayes within the tank. For a visual, It would be like sturring a glass of tea with a spoon.
