Cycle progress.. complete?

[mkoop]

Hello everyone :wave:

First off a bit of info into the cycle:

Fishless cycle began 9.26.13
180DT
75 Sump
180# dry rock
40# live rock (couple nice hitchhikers, small feather dusters and some pods all seem to be doing well... think I have a few small vermetid snails also, not sure about them yet)
200# aragonite special grade sand
SRO2000INT - Running duration of cycle
2x Tunze 6100.1
1200gph return

My Log (I'll just depict the highlights rather than the entire log):

10.5.13 pH 8.2 NH 0 NO2 0 NO3 0
10.10.13 pH 8.2 NH .5 NO2 0 NO3 0 - first ammonia reading
10.13.13 pH 8.0 NH 1 NO2 0 NO3 0
10.17.13 pH 8.0 NH 2-4 NO2 0 NO3 0
10.19.13 pH 8.0 NH 4 NO2 .25-.5 NO3 0
10.22.13 pH 8.0 NH 1-2 NO2 3-5 NO3 20-40
10.24.13 pH 8.0 NH 0 NO2 5+ NO3 40
10.27.13 pH 8.0 NH 0 NO2 5+ NO3 40-80
10.29.13 pH 8.0 NH 0 NO2 5+ NO3 40
10.31.13 pH 7.8-8.0 NH 0 NO2 0 NO3 0-20 (looks like my cycle is complete?)

(** I'm confused, where did all my nitrates go? I have not done a 50% water change yet, is my skimmer removing them all?)

(double check from other side of tank)

skimmer running, I emptied it once a week and changed filter socks once a week during cycle.

overall view

Now, if my cycle is complete, can I go ahead and add a CUC? My 40gB QT tank is only about 10 days into cycle (hindsight should have done the QT first, oh well whats a few more weeks its already been 7 months) so it will be awhile before I have any fish but do you need to QT the CUC also?

 

[hollister]

Cycle over when ammonia is zero could take 2 weeks could take 6 . Also think water flow might be a little low and why do you want to do a 50% water change . Try to never do more then 25 or 30 % per month and I would wait until cycle is over for the water change.

 

[mkoop]

Cycle over when ammonia is zero could take 2 weeks could take 6 . Also think water flow might be a little low and why do you want to do a 50% water change . Try to never do more then 25 or 30 % per month and I would wait until cycle is over for the water change.

The Ammonia is 0, also after head loss my turn over is 6x volume per hour and my total flow is 7500gph consider I have no corals yet this should be more than sufficient from everything I have read.

In addition I read you should do a 50% water change when your cycle is complete, if my cycle is complete as I suspect, I am curious if I should still be doing a 50% water change even though I have no nitrates currently for some reason.

 

[NHATRANG]

I guess there are probably denitrifying bacteria present. I would slowly add some livestocks now (starting with the easiest one first). 50% water change won't hurt, remember there is always margin of error in test kit, so 50% water change would reduce the margin of error.