Yeap I'm minning cryptonight heavy... that is why only 20 H/s... the others give over 40 H/s.

Weird enough I could find any fixed difficult to give me more than 20% acceptable share with XMR-Stak... so I changed the program... I'm using now XMRig and 99% of my shares are being acceptable with 600 fixed difficult (I did not tried other).

Seems like this XMR-Stak was causing the issue... XMRig 2.6 Beta (to support the algo) is working pretty well all day long.

Here my stats:

Pending Balance: 77.1172294 SOLACE
Total Paid: 0.0000000 SOLACE
Next payment: 1.507373408
Last Share Submitted: less than a minute ago
Hash Rate: 22.00 H/sec
Total Hashes Submitted: 546717

Even the pool site (where the hashrate only counts the accepted shares) is giving me ~20 H/s.