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nitrates, phosphates, algae and CO2 - Daphne - APD V4#1267
You are going in the right direction. Pearling is oxygen. The plants
are photosynthesizing well. In all probability, the water column is
oxygen saturated and is somewhere above 8 mg/L. This is happening
because of the added nutrients, especially the nitrogen, in the
presence of good light.
You might question the value of the UV sterilizer. It kills the
nitrogen cycle bacteria. Every healthy aquarium I've seen has some
valuable bacteria cultures. Although you have a low reading of
Nitrite, this is an indication that there isn't nitrifying bacteria
that will transform Nitrite to Nitrate.
Blaming Phosphate for algae proliferation is largely a mistaken
notion. You have PO4 of .07. I have had a tank with 3 mg/L Phosphate,
and had no algae. But, this tank had a full house of other nutrients:
20 mg/L of Nitrate and 0.25 mg/L of iron complex with Potassium
(somewhat equivalent to TMG). Having a good iron test kit is
important. The only one I use is made by HACH. Costs a bit more.
Haven't been comfortable with many of hobby level kits.
Algae thrive in poorer nutrient environments and higher plants don't
do well when there are limiting factors with the nutrients. This is
generally true. However, it is possible that algae can expand when
more nutrients are added. The addition of nutrients perk up the
higher plants, as seen with plants pearling (they are working 100%).
But, during this transitional phase, the algae can also get a boost,
and threaten to be the dominant species. To shift the emphasis away
from algae to higher plant dominance, one needs to physically remove
as much algae as possible. Take the driftwood out and scrape off the
algae and rinse well. With a single edged razer blade, remove algae
from the glass. As a transitional action, add a lot of fast growing
plants like Rotala and Hygrophila difformis or Wisteria. The shear
increase mass of higher plants, replacing the algae plants, may well
shift the balance, and eliminate the algae. I have used the
technique many times, with success. Works every time.
You said: On a related note, my CO2 is still dropping to 6.4 at night
yet it is set at
6.9 on controller.
I think you mean : the pH 6.4 / pH 6.9. Controllers are set to turn
on and off within a bracket. For instance: off at 6.8 and on at 6.9.
At night the pH in the water can go below the setting of 6.8 because
plants and algae respire and give off CO2 (lowering the pH) in dark
periods and use up Oxygen then. This night time CO2 from the plants,
could drop the pH below reach the controller. If this makes sense.