Cycling Question

Hello All,

Long time lurker, first time poster.

I set up my 40Breeder 10 days ago.

Here are my tank's measurements:
PH=7.6
GH=150ppm
KH=150ppm
Ammonia=0ppm
Nitrite=0ppm
Nitrate=5ppm (tap water is 5 after 24 hours also)

I have a Betta in a 1 gallon tank with U/G filter - he's been around
since March. I put the sponge from my new power filter (aquaclear 50 -
old 200) in with the betta for a couple of days and then put it into
my 40Breeder.

I added 5 zebra danios last saturday, and have been feeding them
sparingly the last 10 days.

Question: I have measured the ammonia and nitrites daily for the past
10 days and have seen no spikes or rising at all. Why it this?

1) The seeded sponge now in my power filter can process the amount of
waste the danios put out on a daily basis?
2) The danios don't put out enough waste to registeryet in a tank of
such large relative volume.

I am trying to be patient, but would like some guidance.

Should I continue to wait? Add a couple more danios to help with
increasing waste production?

Thanks in advance for the advice!

Regards,
David