New tank nitrates have spiked ! cycle almost complete ?

[Acipenser]

specs :
26 G Bowfront
at least 30lbs of live rock
2 inches of caribe sugar "live" sand
2 450 gph power heads
100 w fluval heater

ph 8.0
ammonia < 0.25 ppm
nitrites 0.0 ppm
nitrates spiked to 40 ppm
salinity 1.0245
temp 78 deg f

Tank has been running for 1 week, I just did a 4 gallon change and will retest tonight
I am having a hard time being patient and REALLY want to add somthing to my tank .