The formula used in pool source for reward calculation was incorrect. Check this link: https://play.golang.org/p/fTNEvm7jrh
WE FIXED THAT AND OUR POOL MAKE CORRECT REWARDS TO MINERS!
To check rewards that pools send to miners see value in "reward" field. It's should be "285000000", not "280401883" or "2850000000000000000"...
Our pool:
http://etp.altpool.pro/api/blocks
Other pools:
http://cryptopoolpond.com:8080/api/blocks
http://metaverse.farm/api/blocks
http://etp.dodopool.com/api/blocks
http://etp.sandpool.org/api/blocks
Note: for every 1000 blocks found, pool with wrong reward's calculation keep 1000*0.05 = 50 ETP and doesn't pay it to miners.
The extra zeroes are due to differences in precision... Derp