A third-minute goal from Nicholas Nelson directly from a corner kick gave Hydel the lead. Another strike, in the first minute of time added, from Rodari Edwards, sealed the win for the visiting team.
With the victory Hydel moved to 12 points, while Calabar remain on seven.
Donovan Hayles, the elated Hydel head coach, said his players held to the "team's first mission" of winning the group.
His counterpart Bradley Stewart fumed at the standard of the officiating, while saying his team "played well".
Calabar started the more attacking of the two teams on an uneven and patchy field at their Red Hills Road base.
But Hydel had an unlikely early lead through Nelson's right-footed corner kick.
The goal helped Hydel to settle, but by the end of the first half Calabar, fighting for the equaliser, regained their attacking thrust and at times pushed the visitors deep into their own half.
The second half, however, belonged to Hydel, who missed a few good opportunities in front of goal. But they made the three points safe when Edwards struck home sweetly with his left boot, as Calabar threw players forward in a quest for the equaliser.