On Sat, 26 Feb 2005 19:23:17 -0600, "MP"
wrote:

Hi everyone ... we bought an aquarium for our school about 6 months ago and
everything's been going swimmingly until this last couple weeks. There were
duckweed growing crazy ... I kept thinning it out with a net ... and several
leafy plants growing anchored to the substrate. Then 2 weeks ago I noticed
the duckweed dying off ... and now they're virtually gone. One leafy plant
has died completely ... and the other has leaves that look like they're
rotting.

I did some water tests today ... pH was 7.2 ... nitrates, nitrites, hardness
were all "healthy" ... but the phosphates were off the colour chart. I did
a major water change ...

My question is: would extremely high phosphates be responsible for the
plant's deaths? What would cause the phosphates to get so high in the first
place? Is there anything to do besides changing water?

Thanks!

Mike

Hi Mike,

How much light do you have and how many gallons. Plants have
preferred light ranges. If you have a 20 gallon tank and 40 watts of
light your ratio is 2 watts per gallon. "Low Light" plants are best
if the ratio is 1.5 watts/gallon or less. Also consider that new
bulbs put out their rated light only for a few months.

All of my plants are "low light" so I don't worry about aging lights
until the go out completely.

I don't trust my ability to interpret chemistry tests. I have 5 tanks
of different sizes. Only problem since I got the right plants was due
to under feeding my fish in an experiment. My tanks depend on fish
waste for food, too little waste and the plants were starving. Upped
the food and the plants recovered.

Good luck, I hope someone has an answer for you.

dick