[Wet Thumb Forum]-Nitrate/Phosphate eating rate

[aviel]

Hi,

On the last 10 days or so I noticed that nitrate/phosphate levels in my tank wouldn't drop like it used to. I tended to relate that to the fact that my CO2 levels dropped to ~15 ppm during this period without me noticing that. There was(is) also a slight BBA problem just because of that co2 shortage. Anyway - I fixed that 4 days ago, targetted no3=15 ppm and po4=4 ppm and dosed 2 ppm nitrate daily through KNO3, and 0.35 ppm phsophate through KH2PO4. I was expecting the nitrate to drop down from 15 ppm. Yesterday I tested and was suprised to find out that my nitrate levels crossed the 20 ppm and the PO4 exceeds 2 ppm. I have 2.5 wpg, I add (more than) enough iron+trace, I even added 10 ppm K at water change through K2SO4 - So really I don't see a reason for this.

My guess is that during the low CO2 period there was excess of iron/nitrate in my water column which plants couldn't use. They stored it and now that CO2 is back, still they are not hungry yet, hence the high levels.

Makes sense? Or maybe other explanation for this rude behavior of my water chemistry?

Aviel.

[aviel]

Hi,

On the last 10 days or so I noticed that nitrate/phosphate levels in my tank wouldn't drop like it used to. I tended to relate that to the fact that my CO2 levels dropped to ~15 ppm during this period without me noticing that. There was(is) also a slight BBA problem just because of that co2 shortage. Anyway - I fixed that 4 days ago, targetted no3=15 ppm and po4=4 ppm and dosed 2 ppm nitrate daily through KNO3, and 0.35 ppm phsophate through KH2PO4. I was expecting the nitrate to drop down from 15 ppm. Yesterday I tested and was suprised to find out that my nitrate levels crossed the 20 ppm and the PO4 exceeds 2 ppm. I have 2.5 wpg, I add (more than) enough iron+trace, I even added 10 ppm K at water change through K2SO4 - So really I don't see a reason for this.

My guess is that during the low CO2 period there was excess of iron/nitrate in my water column which plants couldn't use. They stored it and now that CO2 is back, still they are not hungry yet, hence the high levels.

Makes sense? Or maybe other explanation for this rude behavior of my water chemistry?

Aviel.

[imported_BSS]

Though my plant growth seems pretty decent, I've pretty much always had this same problem. After a water change, I get my NO3 up to 5-10, my PO4 to 0.5-1.0 and add some trace. Throughout the week, the values don't change much. I likely overfeed, and I just started adding Flourish Iron (which might have been my limiting factor), but I'm very interested in what others might offer as a suggestion on this one.

Brian.