Unfortunately, we can't permit very low pool share difficulty orders because they make mining inefficient and put a serious load on our servers. Keep in mind that we usually send a very high amount of hashrate toward the targeting pool and, therefore, low share difficulty is putting an excessive load on miners, especially on today's fast ASIC miners. These low share difficulties were left in the pools due to historical reasons, but are really inefficient with today's miners.
If you are using your own custom pool, you can easily adjust the higher share difficulty setting in your pool's software (usually just one setting in the software configuration).
If you are using a third party pool, it usually gives you a choice to set worker difficulty under your account page. If not, we really encourage you to contact the pool operator to make this choice available or even better: ask them to increase the global minimum/starting pool share difficulty. If the pool is using vardiff, the initial/starting difficulty for calculating vardiff should be set at our minimum accepted share difficulty. Furthermore, our system only accepts connections to pools with correct and standard extranonce sizes. If the pool uses a non-standard extranonce size, you will have to contact the pool's operator to fix extranonce sizes to standard ones.
Keep in mind: lower difficulties were left in the pools due to historical reasons, but are really inefficient with today's miners. That said - if your orders are disconnected with "Pool difficulty too low" or invalid extranonce sizes, we encourage you to contact the pool operator to ensure that the pool is using a minimum/starting pool share difficulty, which is compatible with our service (and thus compatible with today's miners).
The required minimum initial and running pool difficulty is displayed on the pool operators page. Each algorithm has its own initial and running difficulty, displayed in the field called "minimum pool difficulty". The initial pool difficulty is evaluated while the order is on standby without miners (but still Alive) while running pool difficulty is evaluated when the order starts accepting miners - hashrate is assigned to the order. If the pool operator can't set this for you and setting worker difficulty isn't properly evaluated by the pool, you will, unfortunately, be forced to use another pool that uses higher difficulty.
Keep in mind: pool share difficulty is not the same as network difficulty.
Network difficulty is set by the coin's current difficulty, adjusted according to the aggregated hashrate of all the active miners on the coin's network (more hashrate -> higher difficulty, less hashrate -> lower difficulty). The coin's network difficulty is regulated by the coin's algorithm. Lower network difficulty puts more stress on fast ASIC miners.
The pool's share difficulty is controlled by the coin's pool operator - that is the target end-user pool, not our stratum server proxy pool. It can be fixed or variable - so-called vardiff. Lower difficulty puts more stress on fast ASIC miners since the miner has to process an excessive number of shares in a short period of time. If the miner were to work only on a few shares with higher difficulty, the efficiency of the miner would be higher. Moreover, low difficulty shares affect our system since our proxy has to process an excessive number of shares in a small period of time.