Leigh
The tank is about 6-7 moths old.
Unfortunately I cannot afford compressed CO2 yet. My wife would kill me :-)
I already added more KNO3 to the PMDD but I'll try more.
How much is too much?
I have measured and still do the Ph right before the lights come on and it
is 6.8. During the day and before the lights are out is 7. In the past I had
some Ph crash due to low Kh but little baking soda took care of it.
I don't have any problem with algae. (yet?) The water is crystal clear, some
of the leafs have little green algae growth but the algae cleaning crew is
taking care of it.
What plants would you suggest?
Thanks
Laz

"LeighMo" wrote in message
...
How long has this tank been set up?

It's not necessary for the plants to pearl for them to be growing well.
However, you say they aren't growing well, so something's wrong.

Nitrates should not be zero. You need to get your nitrate level up to at
least
5 ppm. You might also need to add potassium or phosphate.

You have 4 wpg, a lot of light for a 55 gallon tank. That means you have
to be
very careful to keep up with fertilization and CO2 levels. In fact, with
a
tank this size, with this much light, I would recommend compressed CO2.
And it
might help to add more fertilizer. You don't seem to be adding much,
given the
tank size and lighting levels.

Also, try measuring your pH several times a day, just for a day. In the
morning, when the light goes on, in the middle of the "day," and when the
lights go out at night.

Your plant selection is wrong for your lighting levels, too. You need
more
fast growing stem plants, or your tank will be overrun with algae.



Leigh

http://www.fortunecity.com/lavender/halloween/881/