Hmm... One thought would be that the plants were utilizing ammonia as a
nitrogen source while the tank was getting cycled and until the levels of
nitrates rose to some point, the plants were not trying to utilize nitrates
for nitrogen. Not sure. But unless your fish load is going to be large
enough to provide the nitrates your plants desire you will need to provide
some additional nitrates for optimum plant growth.

Ron

"jduprie" wrote in message
news
yep, tanks are pretty much identical. the only difference (other than
size)
is that I've still got a bunch of "starter" (read disposable, expected to
die off) fishin teh new tank - they're a locally available generic feeder
fish - a kind of whitish minnow, sot sure of what they really are.....

Other than that, the tanks are the same...

thanks

--JD


"Ron Nelson" wrote in message
...
Do you have the same plants in all of the tanks? Maybe you added a plant
that loves nitrates? Is the fish load similar between these tanks? What
about lighting?

Ron

"jduprie" wrote in message
news:z3Qpa.602410$L1.171543@sccrnsc02...
I've got somethign I've never seen before. I havea "new" (about 2
months
old) 125 lightly planted tank, witha variety of fish in it. After the
initial cycling, the chemistry had setteld down to a pretty "normal"
ballance, and was staying nice and constant (light presence of
nitrates,
no
ammonia, teeny bit of nitrite).
Then, overnight, *everything* went to zero - none of the test kits
show
the
presence of any nitrate, ammonia, or nitrite. I've never had to add
any
suplements to any of my other tanks, (similar set ups), and I've
always
(and
still do, so the test kits are OK) had traces showing up......

any ideas?

thansk
--JD