Hi,

John, glad to help. But if my post somehow incorrect, please guys who knows better to correct it, we are here to share and learn.

You don't have to have test kits to dose NPK, like RuslanJamil said, using EI fertilizing method, everything is estimative, no need to be accurate. If you overdose, you can always reset by do 50% water change. Some says it is an excess method, everything (NPK) is in excess. It is there where plants need it. It seems that under dose is the main problem for most people.

I have discussed this in length in my tank thread here about making KNO3, KH2PO4 and Epsom Salts solutions. You can also make your own solutions with different volume using this Aquatic Plant Central fertilator to determine how many x grams in y milliliters water to give a specific ppm of each NO3, PO4, K and Mg. It is important too, to know the maximum solubility of each loose ferts. Maximum solubility per 100ml of water for KNO3 is 35.7 grams, KH2PO4 is 22.0 grams, K2SO4 is 12.0 grams and Epsom Salts is 35.6 grams. You can't completely (100%) dissolved 100 grams KNO3 into 250ml of water for example. But, 100 grams KNO3 mix into 500ml of water will completely dissolved KNO3.

Recommended ppm for NO3 is 10ppm per dose, PO4 1-2ppm per dose, K 10 ppm per dose. Dose that 3 times a week. For Mg, if you have soft water, or have some Mg deficiency like curling leaves, dose 2-5ppm Mg either weekly after water change or daily around 0.5ppm Mg. You don't need K from K2SO4, if you dose enough KNO3 and KH2PO4, because K from these two is enough. But if you think you need to dose more K, then by all means, use K2SO4. Anyway, some people like to dose dry, easier, using a teaspoon. If you want to dose dry, take a look at the link provided by RuslanJamil.

After all that, I must say this thread is dedicated to micros, to determine which brand of micro nutrients product used the most in Malaysia and why.

Best Regards