Quote:
Originally Posted by helgymatt
Chucks calc seems to be very helpful, but I have one more question.
The calc tells me how much ppm I will dose for each ml. If I want to hit a target in my tank of 1ppm of phosphate and 10 ppm of nitrate, do I want to hit that target each time I dose (I will be dosing every other day). Or do I want to add less and let it accumulate by the end of the week?
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Without accurate testing, and a lot of it, there is no way to know how much accumulates by the end of the week. Remember, the plants are consuming those fertilizer elements all during the week, so you can't just add up what you dosed. As far as your target goes, only you know what you want. If you want to know you have, at one known time, 10 ppm or more NO3 in the water, then dose 10 ppm each dose. If you want to know you will never have more than 10 ppm during the week, and are doing 50% water changes each week, dose a total of no more than 5 ppm total during the week. (But, if you do that, look for your plant growth to slow down.)
This works so much better if we just follow the EI amounts, adjusting as needed based on plant growth and watching the plants carefully. I do mine in premixed solutions, by using the formula Tom showed above, adding that much of a fert to a bottles worth of doses. I use two bottles, one for micros and extra magnesium and one for the macros. I dose every day, both bottles.