Nitrate question

[reefworm]

The 29 rebuild has been on hiatus since Sept. '07 for a variety of frustrating reasons At that point, all the hardware was in place, although the skimmer wasn't running [powerheads, Mag 7 return]. About 2" of sand, and 15# of live rock added to existing dead rock from the old set up for a total of about 25-30# in the display. Sump is an old wet/dry with no bioballs, but around 5+# of liverock in its place.

No animals added. Some green hair algae and some green macro [not sure of type]. and brown patches on the sand and brown film in patches on glass [scrapes away in a film]. Diatoms?

Temp: 83.4 [normally around 80~81 - MH ran w/o fan for a few hours]
pH: 8.12 [pinpoint meter]
SG: 1.026 [refractometer]
Ca: 371 ppm [will resume 2-part additive and kalk drip] [LaMotte]
Alk: 3.12 meq/L [LaMotte]
Ammonia: 0 [Salifert]
Nitrite: 0 [Salifert]
Nitrate: 7.0! [LaMotte]

Is this a cycle on hold? Should it be waited out or handled directly? What would you suggest is the source, since the tank is not being fed and there are no animals in the tank? There was a sizeable chiton that hitchhiked in on the live rock that I'm not seeing now and am presuming has died. One tiny hitchhiker snail is working the glass. I am seeing a number of bubbles under the sand that rise to the surface from time to time. Has the substrate become a nitrate trap over the last weeks? Should it be stirred up? Any observations/suggestions much appreciated.

thanks!
-rw

[reefworm]

^

[landlord]

Have you been doing any water changes with water containing detectable Nitrates?

Dumb stretch here but: I have noticed that on my open top 29 gallon bowfront I had a swarm of house gnats decide to make a landing on the waters surface only to die and sink to the bottom (possible Nitrate source)
Just fishing with ya --landlord

[landlord]

It sounds like your sandbed is converting the Nitrate to Nitrogen gas so it is getting in there somehow. Perhaps just natural liverock die-off / decay.

[reefworm]

thanks - I'm planning on stirring up the sand a bit to release the bubbles, then do about a 20% water change.