Bunbuku

Dear Seachem

I noticed that on-line Dose calculator for Nitrogen has mEq/L as the unit while the other components are expressed in ppm (mg/L). What is the conversion to ppm of NO3? Divide the answer you get by 5?

It would also be nice to include a recommended range for the final concentrations of different the NPK products.

Seachem

Thank you for pointing that out. That is actually a typo and should be mg/L. We will fix that right away! We do recommend a level for phosphorus on the dose calculator, but the nitrogen and potassium are such circumstantial factors (ie: dependent upon type of plants) that it is sometimes better to let the hobbyists research their specific plants to determine requirements for their tanks. I think most would agree that anywhere from 10-20 ppm of potassium is an acceptable range and about 5-10ppm (nitrate amount) of nitrogen is sufficient.

Bunbuku

I guess part of the confusion is Nitrogen vs Nitrate as I understand that Fluorish Nitrogen is not just NO3. Second the on-line calculator requires that "current" nitrogen to be entered. How would I determine this? I have the API Nitrate kit but that only measures part of the total nitrogen - which was zero BTW in my tank

I also noted that if you cross check the required dose with this http://www.seachem.com/support/PlantDoseChart.pdf you get very different results.

Seachem

I understand your confusion I will try to explain as clearly as possible, so here goes:

You are correct: Flourish Nitrogen provides nitrogen in both the nitrate form and the plant-preferred ammonium form. Therefore if you have been dosing Flourish Nitrogen, because one-half of the nitrogen in Flourish Nitrogen is from nitrate, you can get a reasonable estimate of nitrogen levels by doubling a nitrate reading.

However, if you have not been dosing Flourish Nitrogen and you are trying to figure out how to do so, you can take a nitrate reading and divide it by 4.4 to obtain the nitrogen level in your tank. That number (4.4) represents the nitrogen portion of nitrate, figured out by the following:
Nitrate = NO3 --> Molecular weight: 1 Nitrogen (14) + 3 Oxygen (3 x 16) = 62
Nitrogen in Nitrate = 62 / 14 = 4.4

To target a specific nitrogen increase, dose according to the following formula: 0.25vn=m, where v= volume of tank in gallons, n=desired nitrogen increase (if using a “nitrate equivalent” value for “n,” then use a factor of 0.05 instead of 0.25 in the formula) and m=volume of product to use in mL. So for example, say you have a 20 gallon tank, you have a 0 nitrogen level, and want to increase it by 2:
(0.25)(20)(2) = m
10mL = m

Or, say you want to raise your nitrate level by 10:
(0.05)(20)(10) = m
10mL = m

This required dose does not match the Plant Dose Chart because the required dose that you can calculate allows you to target a specific nitrogen increase. The Plant Dose Chart is merely a suggestion (i.e., general schedule) to dose all of the Flourish products and maintain levels. Your dosing regimen will depend greatly on a variety of factors, including lighting, initial water quality, how heavily stocked your aquarium is, substrate selection, and types of plants.

Bunbuku

Thanks Seachem! That makes more sense now!

I have not measured the NO3 concentration right after adding Fluorish Nitrogen in the mornings. However, I do know that at night several hrs after the photoperiod is over the NO3 levels are undetectable. Are there any adverse consequences of allowing the NO3 levels to go to 0 when the lights are out?

Seachem

No, this should not cause any problems whatsoever.