the tank is fairly heavily stocked with both plants and fish. Its a
community tank - guppies, swordatils, zebra danios, tiger barbs, croy cats,
an algae eater, and a fairly dense plant population - java ferns, some
assorted swords, and some random talling plants (LFS can't tell them apart,
and I don't bother)

Lightly fed on standard flake food twice daily (the food gets eaten up
within a couple of minutes, so I pretty sure I'm not overfeeding).

I do a 50% - 60% water change every week. Well water, run through an ion
exchangeer to remove excess iron.

Whats mystifying is that this tanks has been set up for a good while, and
has been stable. I haven't changed anything, but the nitrates suddenly
spiked, so something in the tank obviously changed.

--JD

"Marco Schwarz" wrote in message
...
Hi..

my nitrate levels in a 120 are pretty high (for fish
anyway - around 40-50)

Hmm.., I suppose 10-20 mg/l (ppm) were enough..!

But how is the nitrate level of your tap(?) water..?

What's about water changes..?

And how is this tank stocked and fed..?

--
cu
Marco