Greenish color tank water?!?

[Thomas Ngo]

My brother needs help with his GF tank. The tank water keeps turning
green/yellow color and very cloudy within 3-4 days after he does 50%
water change. During the last 4 weeks, he's performed 50% water change
for his tank at least 4 times but no sign of improvement. What's going
here?!? I live in the same area with him and I do not have any problem
with my tank. Furthermore, my 75G tank is even much more crowded than
his. I have 10 large fancy GF and 3 small ones.

Here is some info about his tank:

o 58G Oceanic Show Tank
o 4 large (about 3.5") orandas and 1 small calico oranda
o Emperor 400 powerfilter
o 5 plastic plants
o 2" coated gravel
o hard water with pH 7.6
o No heater but the house temp is very much around 70F deg

The tank was completely cycled 5 months ago. The last fish was added
about 2 months ago. The tank water was crystal clear when I came to see
his new fish.

Any info would be greatly apreciated before he gives up this wonderful
fish keeping hobby :-( . Well, it's all started from me...

Thomas

[GTong]

In article <338469B6...@atsmail.lucent.com>, Thomas Ngo
<tn...@atsmail.lucent.com> wrote:

>My brother needs help with his GF tank. The tank water keeps turning
>green/yellow color and very cloudy within 3-4 days after he does 50%
>water change. During the last 4 weeks, he's performed 50% water change
>for his tank at least 4 times but no sign of improvement. What's going
>here?!?

First, clear water is not a sign of a clean or healthy tank. Ammonia is
clear after all.

Second, some tint to the water--yellowish, greenish--is good and indicates
that the water is supporting algae.

Third, if the algae gets out of control, you might want to take steps for
aesthetic reasons. Here are some suggestions:

1. Keep lighting to no more than 11 hours a day. No direct sunlight.

2. Keep nitrates and phosphates as close to zero as you can. Has your
brother tested his water for these? Four 50% water changes in four weeks
really isn't a lot ... The water changes have to stay ahead of nitrate and
phosphate accumulation in the tank.

3. Don't overfeed the fish or overfertilize the plants. Both affect #2
above. How do your brother's feeding habits compare to yours ... ?

Finally, he can try attaching a diatom filter to his system. These can
often remove small, suspended algae from the water. Otherwise, I wouldn't
worry about it.

--
"Every infinity is composed of only two halves."