Re: Carpeting algae

[Thomas Barr <tcbiii at earthlink_net>]

> 
> Therefore i need your help to:
> 1) understand what are the conditions for the algea to appear and grow
> 2) find a way to eradicate the algea
> The tank is a display tank containing: heckel and alenquer wild discus,
> various varieties of apistogramma, corydoras sterbai, hypancistrus zebra,
> tetra cardinals, caridina japonica, otocinclus. plant species include: java
> moss, anubia barteri and nana, nomaphila stricta, tiger lotus, echinodorus
> amazon.
> Temp = 26-27 deg Celcius  (78-80 F)
> pH = 6.9
> conductivity = 170 uS

A measure that will help for determination is carbonate harness(KH).
You likely have water that's too pure and not enough HCO3- and or GH(as
CaCO3). Conductivity doesn't tell which ions, but is a good measure for
water purity and many very soft water /RO test use this measure. Not much
use for planted tanks generally.

> filter is magnum 350 containing lava rocks and white coton type of filter
> (don't know the general name for it).
> Watter changes are done ones a week (20%) except when discus fry are
> present.

That's not much water to change weekly for Discus.
You have BGA or cyanobacteria. Oscillitoria.

Try turning off the lights for 3-4 days and dropping a blanket over the
tank. Do a 50% water change before and try to remove as much as you can,
BEFORE you do this.
I assume your feeding a lot of food. If you continue without doing more
water changes(Volume and or frequency) you'll likely get BGA again. If not
that type, something else will take its place.
You'll need a KH/GH of at least 3 on the German scale(about 50ppm). Lower is
going to cause problems for plants.
You can look at the pH/KH/CO2 table for seeing how much CO2 your water has.
Try to get about 20ppm-30ppm. Do you use CO2?

Causes for algae typically, low CO2, low/too high NO3, NH4. Most folks don't
have many issues if these are dealt with. CO2 relates to KH/pH.
Poor plant growth=> algae growth of some type or form. Good plant growth=>
lack of/less algae.
Nothing eats BGA, some snails will nibble old half dead BGA.

Someone will chime in and tell you to use Erythromycin. I don't think it's
needed since you can use lights off and that's free. BGA is easy to kill
with that method.
Just be sure to help the plants grow so it doesn't come back. You will not
limit it with chemical removers etc.


Regards, 
Tom Barr