Ei Questions

[silvery37]

I have read the thread on using fertilizers and EI. I understand how it works. When I plug the recommended amounts of potassium phosphate into a calculator them seem very high. For example, in a 10-20 gallon tank 1/32 of a teaspoon of KH2PO4 should be added three times a week. From chucks planted aquarium calculator this adds 1.47ppm of phosphate each time it is dosed. This works out 4.5ppm of phosphate a week and levels would eventually rise to around 9ppm not counting plant uptake. The recommended level of phosphate is 1-3ppm. Am I missing something? Is it because smaller amounts of potassium phosphate are difficult to measure?


When I calculate my dosing amounts should I add half of my required level per week or the entire required level each week? For example if I want to have 30ppm of nitrate in my tank should I add 15ppm per week or 30ppm. Doing the math by adding 15ppm per week I would reach a steady level of 30ppm in about a month by doing 50% water changes. Although I am only adding 15ppm per week half of the previous weeks fertilizer is still in the tank. This does not account for plant uptake.

 

[plantbrain]

I have read the thread on using fertilizers and EI. I understand how it works. When I plug the recommended amounts of potassium phosphate into a calculator them seem very high. For example, in a 10-20 gallon tank 1/32 of a teaspoon of KH2PO4 should be added three times a week. From chucks planted aquarium calculator this adds 1.47ppm of phosphate each time it is dosed. This works out 4.5ppm of phosphate a week and levels would eventually rise to around 9ppm not counting plant uptake. The recommended level of phosphate is 1-3ppm. Am I missing something? Is it because smaller amounts of potassium phosphate are difficult to measure?

Is 9ppm any worse, bad vs 3ppm?
would you think 9ppm cause algae but 3ppm not?
1/32 is a small amount and variations can occur, I generally add about 3ppm per week.
But adding more dose no harm.......

When I calculate my dosing amounts should I add half of my required level per week or the entire required level each week? For example if I want to have 30ppm of nitrate in my tank should I add 15ppm per week or 30ppm. Doing the math by adding 15ppm per week I would reach a steady level of 30ppm in about a month by doing 50% water changes. Although I am only adding 15ppm per week half of the previous weeks fertilizer is still in the tank. This does not account for plant uptake.

This is fine(using less) as most every tank should use less..........however, more is not bad in these ranges.
A method that is suggested in the EI article, start high and reduce the levels down slowly till you see a negative response, then bump back up to the next higher dosing level.

That method + EI adds "just enough".

If you start too low, then seeing a negative response is where you start off at(too little), that's a poor starting place to determine the just enough amount.

Look at the graph in the Article, the range of non limiting growth is large, while the upper range to toxicity is very high, PO4 has no known toxicity for fish or plants. NO3 is very high(well into the 100-200ppm ranges for NO3 derived from KNO3).
So taking the high road here and reducing down vs starting low and coming up makes far more.

Regards,
Tom Barr