If you don't want algae then you need to monitor your tank parameters,
especially phospate and nitrate.

Read about the redfield ratio...
http://www.xs4all.nl/~buddendo/aquar...dfield_eng.htm


You can estimate CO2 based on pH and KH...

http://www.thekrib.com/Plants/CO2/kh-ph-co2-chart.html

If you tap water has lots of nitrate then either use RO water or use a
nitrate sponge such as NitraZorb
http://www.aquariumpharm.com/en_gb/p...ame=Filtration

This stuff will soak up pretty much all your nitrate which won't do your
plants any good but you can use it 24hours before a water change to reduce
nitrate to zero, then when you add your new water you will add nitrate but
it will be diluted into the existing tank water.

--
Best regards
Mark

"Koi-Lo" None wrote in message ...
*Note: There are two "Koi-Lo's" on the pond and aquaria groups.

"Mark Baldwin" wrote in message
...
The best way to avoid algae is to make sure your plants have everything
they need to grow, then they will simple outcompete the algae for
nutrients.

I'm using Excel and Flourish micronutrients plus extra Potash and still
have an algae problem. :-( The black sooty algae has been replaced by a
black wiry, very ugly algae now. Neither the goldfish, the otos nor the 2
plecos will eat it.

This isn't an easy thing to do since if your missing just one nutrient
then the plants will slow down and the algae increase.

How can anyone possibly know without extensive expensive testing what that
nutrient can be?

Generally...

Phospate - 0.1ppm

No test for that one.

Nitrate - 5ppm

Mine stays around 15 to 20ppm, as it comes from the tap.

CO2 - 20-35ppm

No test kit for this one either.

GH - 3 ( calcium/potassium/magnesium )

Over 300 and alkaline - 7.5 and above.

You say you have no phospate - this will limit plant growth and you will
probably see green algae on the glass and leaves.

We get the red-black sooty or wiry algae.

If you have algae on the water surface it's a sure sign of overfeeding.

pH of 6.8 and KH of 3 means approx 14ppm of CO2 - the plants will grow
better if the CO2 is above 20ppm (just change your KH to 4)

Don't use any pH buffers!

--
Best regards
Mark
--
Koi-Lo....
My Pond & Aquarium Pages:
http://tinyurl.com/9do58
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