Cycling - confused about NH3,NO2,NO3 levels at day 12

[EricL.]

Hey, it‘s me again with another question

We are at Day 12 of cycling our new 250l tank. It is equipped with live sand, but dead rock. It is a used tank that we bought on eBay. We cleaned it very tidy before starting to cycle. We used a dead shrimp to start the cycle. It is heavily decomposed already.
At this point, we are a little bit confused about the levels of NH3,NO2 and NO3 we measure. Here are our graphs of those:

Based on these graphs, what do you think? Where are we standing? I also fail to understand the Nitrate-graph? We did not change any water and yet it dropped?

Thanks for your help!
Eric

 

[Quietman]

At some point soon you should take the shrimp out. It's still going to produce ammonia so readings are going to be a bit harder to interpret. Just add some food every now and then and it'll decay just fine (if you're not added fish right away).

Hobby grade test readings aren't that accurate, it's more trend monitoring and level of magnitude. Variations are normal.

I'd say your very close if not cycled. Remove the source of ammonia - if it drops to 0 in a day - you're good. Nitrites aren't a toxic issue in saltwater.

 

[EricL.]

Thanks for your reply! We are now experiencing cyano /diatoms.