Basic Aquarium Fertilizer Dosing
Why your 10 gallon tank needs more light than the WPG rule states.
Note that these are guidelines and this is NOT a comprehensive dosing guide. There most likely are rounding errors. To check the numbers your self you can do a Google search for Chuck Gadd. He has a on-line calculator on his web site and a Windows calculator that you can download. You can also go to Aquatic Plant Central, (requires registration).
I highly suggest that you invest in a digital gram scale with at least 0.1 gram accuracy. Weighing powders is MUCH more accurate than volume measurements. And many people seem to get the tablespoon and teaspoon mixed up. And fractional teaspoon sets, the infamous smidgen, pinch, dash, are highly suspect and inaccurate. The same markings have been used on fractional tablespoon sets and fractional teaspoon sets.
You can pretty much dose everything at once with one exception. Don't dose KH2PO4 at the same time as iron containing ferts. If you want more info on dosing see my dosing guide. Or do a Google search for Estimative Index.
Plantex CSM+B:
- Mix 2 tablespoons (30 grams) with 2 cups (473 ml) of water.
- 1 ml of this solution will add 0.1 ppm of iron to 10 gallons of water.
- 0.1 gram dosed dry in 20 gallons of water will add 0.09 ppm of iron.
- Suggested iron levels are 0.1-0.5 ppm
KH2PO4
- Mix 1½ teaspoon (7.2 grams) with 250 ml of water.
- 1 ml of this solution will add 0.53 ppm of phosphates to 10 gallons of water.
- ¼ teaspoon (1.2 grams) will add 12.86 ppm of phosphates to 20 gallons of water.
- Suggested phosphate levels are 1-2 ppm or 10% of your nitrate levels.
KNO3
- Mix 1 tablespoon (16.8 grams) with 250 ml of water.
- 1 ml of this solution will give you 1.08 ppm of nitrates and 0.54 ppm of potassium in 10 gallons of water.
- ¼ teaspoon (1.4 grams) will add 22.5 ppm of nitrates and 14.26 ppm of potassium to 10 gallons of water.
- Suggested nitrate levels are 10-20 ppm. Suggested potassium levels are 20 ppm.
- NOTE: These values are correct (there will be rounding errors). If your test kit doesn't reflect these numbers then suspect the test kit.
- There is NO such thing as weak KNO3. Click here to see how to make reference solutions to test your test kit.
K2SO4
- No directions on how to make a solution. Best dosed dry.
- ¼ teaspoon (1.5 grams) will add 16.5 ppm to 10 gallons of water.
- Suggested Potassium levels are 20 ppm.
Chelated Iron
- Mix 35 grams of powder with 2 cups (473 ml of water).
- 1 ml of this solution will raise the iron level in 10 gallons of water by 0.2 ppm.
- Suggested range for iron is 0.1-0.5 ppm.
CaCl2
- 5 grams will raise the calcium levels of 10 gallons of water by 47.7 ppm.
- Recommended range is 10-30 ppm.
Grumpy's GH Booster
- 5 grams will add the following to 10 gallons of water:
- 25 ppm K+
- 39 ppm CaCO3 hardness equivalent (just over 2 dGH) (breaks out as 26.6 ppm Ca as CaCO3 and 12 pppm Mg as CaCO3)
- 12 ppm Mg
- 0.15 ppm Fe
- 0.07 ppm Mn
- And will raise the GH just over 2 dGH.
Mg2SO4*7H2O
- ½ teaspoon (2.7 grams) will add 7.03 ppm of Magnesium to 10 gallons of water.
- Suggested Mg levels are 5-10 ppm
CaSO4
- 1 gram will add 7.29 ppm of Calcium to 10 gallons of water.
- Suggested Ca levels are 10-30 ppm
Dosing suggestion:
- 20-40 gallon tank:
- 50% water change each week
- ¼ teaspoon KNO3 three times a week
- 1/16th teaspoon KH2PO4 three times a week*
- 1/8th teaspoon K2SO4 three times a week
- 5 ml Plantex CSM+B three times a week (do not dose with KH2PO4)
- 1-2 ml Iron three times a week (do not dose with KH2PO4)
40-60 gallon tank:
- 50% water change each week
- ½ teaspoon KNO3 three times a week
- 1/8th teaspoon KH2PO4 three times a week*
- ¼ teaspoon K2SO4 three times a week
- 10 ml Plantex CSM+B three times a week (do not dose with KH2PO4)
- 2-4 ml Iron three times a week (do not dose with KH2PO4)
*Note: If you dose KH2PO4 at the same time as Plantex CSM+B or iron you may get the formation of iron phosphate which is almost impossible to dissolve in water.