Huge spike in nitrates after 5 days of cycle

Day 1 - ammonia between 1-2
Day 2 - Ammona 2, Nitrite 5
Day 3 - Ammona 2, Nitrite 5
Day 5 - Ammona .5, Nitrite 5, Nitrate 10
Day 5 - Ammonia .25-.5, Nitrite 2.0? Nitrate 160

Added Dr Tims one and only one days 1 and 4. 15 pounds live ultra fiji rock with 15 pounds live carib sand. 14 gallon biocube. Purigen in chamber.

What is going on with this huge spike in nitrate? Is an order of magnitude increase overnight normal?

Seems like there has been some algae growing on the glass which I have scraped off. Don't know if it is algae or if it contributes.

Any ideas as to what caused this huge change in nitrates? I didn't add any livestock or anything other than the Dr Tims between the two days.