pamd

I recently went on a three-week trip to Florida. When I left, the ammonia and nitrites were both at 0 for my cycled tank, and the nitrates were at 10 ppm. Since I had to impose on a friend to care for the tank and fish, I only asked him to do a 30% water change one time at the halfway point through my trip. I figured that was pushing it, but to my surprise upon my return the ammonia and nitrites were still 0, and the nitrates had gone down, according to my test kit, to 5 ppm.

Is this possible with only one water change during this time period? Can nitrates actually go down practically on their own?

The tank is six gallons and houses one female betta and a pygmy (Habrosus) Cory cat. I use the API master test kit, and know to shake the heck out of Bottle #2 for the nitrate test.

The aquarium has a couple of live plants and lots and lots of green algae plus diatoms (so much that the algae practically covered the inside of the tank by the time I got home). As far as I know, the plants use nitrates for fertilizer, but I still would have thought the fish waste would have overcome this and expected the nitrates to be higher.

Thanks in advance for any help and insight!

Cody

i hate test for nitrate there so many steps, its a pain.. and yes a simple water change can freshen things up pretty quick