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What you should not do is mix KH2PO4 and any Fe trace mix in a bottle in order to dose them together. The concentrations in the bottle will be such that the Fe and PO4 will combine (FePO4) and precipitate out.

However, adding each separately to a tank shouldn't be a problem as they will very quickly become very diluted. Using autodosing I dose both every day but just to be on the safe side they are dosed a couple of hours apart. I probably wouldn't have any problem dosing them within minutes of each other or even at the same time at different spots in the tank...
 

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2 notes
- CaCO3 has limited solubility so you may want to pre mix it in a little hot water, then add it in w/ replacement water during a pwc.

K2HPO3 (dibasic potassium phosphate) is more readily soluble than the monobasic variety and it adds twice the K per unit. Drawbacks - may not be as readily available to everyone, pH is higher than for the monobasic. There is a "tribasic" out there, but it's even less common in labs etc., pH would be higher still and it's no more soluble than dibasic (if memory serves).
 

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Well let me see if i understand everything :)

I'm used to liquid solution, litters and grams so i will use this units ;) and i will use Chuck's online calculator

I'm going to try EI in a 30 litter water tank (7.93 gallons) so will pick the 10-20 gallon example (off course i will reduce a little the fertilization, but thats a detail for now)

10- 20 Gallon Aquariums

+/- 1/8 tsp = 0.125 g of KN03 (N) 3x a week
+/- 1/32 tsp = 0.15 g KH2P04 (P) 3x a week
+/- 1/32 tsp (2ml) Trace Elements 3x a week
50% weekly water change

As i say i will make a 250 ml of KNO3 and 250 ml of KH2PO4 and i will fertilize 5ml 3x a week. So by my math:

KNO3
6.2 g for 250 ml = 0.51 ppm => 0.51 ppm * 5 = 2.55 ppm = 1/8 tsp of KNO3

KH2PO4
7.5 g for 250 ml = 0.7 ppm => 0.7 ppm * 5 = 3.5 ppm = 1/32 tsp of KH2PO4

Please let me know if this math is correct!

This is a simple example of what to do to convert dry ferts in solutions ferts :cool:
 

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Discussion Starter · #25 ·
The goal is to have at least 5 ppms of Nitrate per dosage. So by increasing the KNO3 mixed in the 250 ml solution, we can get 1 ppm per 1 ml dosed.

KNO3
12 g for 250 ml. 5 ml of stock solution dosed is 5 ppm of N, thereby hitting the target goal.

KH2PO4
Calculations above look good. However, instead of using the full 5ml dosage, only 2-3 ml 3x a week is needed.

-John N.
 

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Ok guys... I have a 160 gallon aquarium that is planted and I want to try EI dosing. I am completely new to the EI dosing scene and want to know what I should buy from Greg Watson's, and what would be a good dose amount and how often?

THx
 

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Assuming you have average tap water, you need KNO3 and KH2PO4. You also need a source of trace elements, which can be Greg Watson's CSM+B or it can be a commercial trace mix, such as Flourish. Your big tank will go through commercial trace mixes pretty fast, so CSM+B would be the best idea. Assuming you have about 300 watts of PC quality light with good reflectors, I would start by dosing 2 tsp KNO3 3X per week, 3/4 tsp KH2PO4 3X per week, and 1/2 - 3/4 tsp CSM+B (dosed dry) 3X per week. If you have much lower light than 300 watts, I would cut down to 2X or less per week. If your water has a low GH, or little or no Mg component of the GH I would dose Greg Watsons Barr GH builder too.
 

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:rolleyes: Sorry, I just realized I referenced this same thread... Not enough coffee that morning... :p

For a 160g you could start out with the dosing suggested for a 100-135 gallon tank. Watch the plants and adjust accordingly. Assuming 140g of water in your tank, that dosing will give you almost 10mg/l of NO3 per dose and just over 3mg/l of PO4 per dose. You could even start out with slightly lower PO4 dosing.
 

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EI target ranges
CO2 range 25-30 ppm
NO3 range 5-30 ppm
K+ range 10-30 ppm
PO4 range 1.0-2.0 ppm
Fe 0.2-0.5ppm or higher
GH range 3-5 degrees ~ 50ppm or higher
KH range 3-5
These ranges, are they weekly totals?

Using the suggestions higher up in the post, in a 50 gal I get
25.27ppm NO3 a week
7.74ppm PO4 a week and
19.11ppm K a week assuming zero plant uptake.

So that puts NO3 & K in the right range, but PO4 nearly 6ppm too high. I realize that Toms point is excesses are ok if there is nothing lacking but this seem excessive when reduced KH2PO4 can be dosed and adding K2SO4 to make up for the loss in K.

I am I reading it right that there is too much PO4 according to the listed target ranges?
 

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Discussion Starter · #34 ·
As you noted, the ppms per week represent the chemical accumulation without any plant uptake or consumption. Of course zero uptake is not what happens in our aquariums. The wide ranges listed above describe the daily totals with uptake that can happen through the course of a weekly dosage. What does that mean?

Plants consume a good amount of the nutrients in high light situations each day, however they can't eat all of it! From day one, the nutrient load climbs into the upper excess tiers by the end of the week. The 50% weekly water change flushes the system so that the levels are then reduced.

The more debated day to day range can be denoted as:

CO2 range 25-30 ppm
NO3 range 5-15 ppm
K+ range 10-15 ppm
PO4 range 1.0-2.0 ppm

-John N.
 

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Thanks for your reply. I understand what you are saying, but can't understand why all the levels are within the suggested targets except the PO4. As these are assuming zero uptake, is it assumed that the plants will consume PO4 faster than the other levels and so these excessive levels won't be seen?
 

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Discussion Starter · #36 ·
PO4 is dosed in low quantities and also consumed in low quantities, whereas the other chemicals have a wider range and wider range of consumption values. It can be stated that 3ppm of PO4 dosed between day 1 and the next dose on day 3 will be consumed to its depletion. I'm not sure if that makes sense to you, but I'm sure there will be a better explanation than mine coming along.

-John N.
 

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Thanks for the abundant amount of information. Now to digest it all and figure out what I need to do for my tank.
 

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If dosing flourish comp instead of CSM+B how much would i add for a 20-40 gallon tank? Also would i want to add flourish iron on which day? i have a 37 gallon tank
 

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Discussion Starter · #39 ·
For both Seachem Flourish and Iron, dose according to the directions on the bottle. Dose both on the micro element dosing days, and do the 50% waterchange at the end of the week as normal.

-John N.
 
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