Nitrate dropped to zero

[martinmcnally]

Anyone know what causes Nitrate to suddenly drop to zero, other than a complete water change? I was at about 10ppm just a week ago and now reading zero. Tested it twice thinking i screwed up the first time.

Tank has only been running for a month so far. Getting some green algae growth on the sand bed but not on the rock, perhaps that is what is sucking the nitrate out?

On the same note my Ammonnia is still reading 0.25 but at this point I think the test kit is not giving accurate results, i have never been able to get it to read lower than 0.25.

Some other paramters:
Salanity: 1.0025
pH: 8.2
Nitrite: 0
Nitrate: 0
Ammonia: 0.25 (or so it claims)
Alk: Normal
Capacity: 75g
Waterchange: 7g weekly