EI regime - K and Mg deficiencies?

[kadoxu]

Hi,

I have some questions about my EI regime. I currently dose 3x Macro and 3x Micro(Seachem Flourish) weekly, with CO2 and Excel.

The Macro solution is made using the @Aquarium Plant Food UK's EI starter kit, so for 500mL of water I added:

• 4tsp Potassium Nitrate
• 1tsp Potassium Phosphate
• 6tsp Magnesium Sulphate

And according to the Dosing Calculator, it provides the following on a single day of Macro dosing:

• Nitrate - 18.64ppm
• Phosphate - 5.84ppm
• Potassium - 2.4ppm
• Magnesium - 3.84ppm

According to UKAPS - Dosing with dry salts the recomended weekly dosing:

• Nitrate (NO3) 20ppm per week
• Potassium (K) 30ppm per week
• Phosphate (PO4) 3ppm per week
• Magnesium (Mg) 10ppm per week

So, since I dose these 3x a week, Magnesium seems to be right on the spot (just above 11ppm), Nitrate (56ppm) and Phosphate(17ppm) way to high and Potassium (7ppm) way too low.

I have a few algae species in the tank and a few older leaves with small holes in them, which makes me think about Potassium deficiency.

Should I reduce Nitrate and Phosphate sources in the Macro solution and add Potassium Sulphate to it?

UPDATE:
I miscalculated the amount of potassium in the Macro solution and found out the issue was low CO2.

 

[ian_m]

Physical plant defects, holes, tears etc and algae generally indicate poor CO2 rather than ferts. EI so overdoses that unless you have got your teaspoons wrong or dosing amounts wrong it is very very unlikely to be a lack of ferts issue.

I would sort your CO2 as a first attack at problem solving.

 

[kadoxu]

Physical plant defects, holes, tears etc and algae generally indicate poor CO2 rather than ferts. EI so overdoses that unless you have got your teaspoons wrong or dosing amounts wrong it is very very unlikely to be a lack of ferts issue.

I would sort your CO2 as a first attack at problem solving.

Yes, CO2 is probably the reason... I did a little more research yesterday and I believe my CO2 levels were way too low. I used to focus on bubble count, but I need to check PH levels instead. My KH is 12/13 and My PH is 7.9/8.0 and it was only going down to 7.5 during CO2 injection. I think PH should go down to at least 7.3 for the plants to have enough CO2 on low/medium light.

But I will still need to teak my ferts as my Nitrate levels are too high even after water changes. I'm thinking about reducing Potassium Nitrate and adding a bit of Potassium Sulfate to compensate the Potassium loss.

 

[dw1305]

Hi all,
I'm pretty sure something is wrong with the calculation,
KNO3 is 39% K and 61% NO3
and the two possibilities for potassium phosphate (K2HPO4 or KH2PO4) are:
45% K, 18% P and 29%K, 23% P respectively.

cheers Darrel

 

[kadoxu]

Hi all,
I'm pretty sure something is wrong with the calculation,
KNO3 is 39% K and 61% NO3
and the two possibilities for potassium phosphate (K2HPO4 or KH2PO4) are:
45% K, 18% P and 29%K, 23% P respectively.

cheers Darrel

You are right!! I forgot to add the K from Potassium Nitrate...

 

[kadoxu]

Potassium Nitrate adds 11.76ppm of Potassium on a single dosage.

So total Potassium should be 14.16ppm on a single Macro dosage... not 2.4ppm...

 

[AverageWhiteBloke]

It's threw me a few times James Dosing Calculator although I use it all the time for simplicity. As you can see most sites recommend dosing 2-3 ppm per week but on James...

What amount of nutrient you wish to add depends on your dosing schedule but if dosing Estimative Index then here is a general guide:
8ppm of Nitrate which is added 3x a week
2ppm of Phosphate which is added 3x a week

which is actually 6ppm per week. My understanding is that if you are dosing at the correct EI levels of PO4 and KNO3 then there is enough K in both of them to cover the K required.
With my dosing if I mix my bottles so each 20ml dose adds...

Kno3 7.36 x 3 =22.08 ppm weekly
PO4 1.12 x 3 =3.36 ppm weekly
the amount of K derived from the two above equates to 5.1ppm x 3 =15.3ppm weekly. You probably have pointed out to me that my K is low 😀 however, I've not any issues dosing at those levels and yours appear to be a lot higher than mine. I don't think K is as important as the no3 or the Po4 and is more in-line with the traces. The plants needs some to metabolise the other two.

 

[kadoxu]

It's threw me a few times James Dosing Calculator although I use it all the time for simplicity. As you can see most sites recommend dosing 2-3 ppm per week but on James...

which is actually 6ppm per week. My understanding is that if you are dosing at the correct EI levels of PO4 and KNO3 then there is enough K in both of them to cover the K required.
With my dosing if I mix my bottles so each 20ml dose adds...

Kno3 7.36 x 3 =22.08 ppm weekly
PO4 1.12 x 3 =3.36 ppm weekly
the amount of K derived from the two above equates to 5.1ppm x 3 =15.3ppm weekly. You probably have pointed out to me that my K is low 😀 however, I've not any issues dosing at those levels and yours appear to be a lot higher than mine. I don't think K is as important as the no3 or the Po4 and is more in-line with the traces. The plants needs some to metabolise the other two.

What plants are able to metabolize also depends on the availability of CO2 and the amount of light that they get. Since I have medium low light in my tank I wouldn't be worried if my calculations showed about half the recommended dosage... but it was showing less than that and I got a bit freaked (as usual).

But as Darrel pointed out, my calculations were wrong... when calculating the K I only used the amount provided by Potassium Phosphate and forgot to add the K provided by Potassium Nitrate. So I'm dosing the following 3x a week:

• Nitrate - 18.64ppm
• Potassium - 14.16ppm
• Phosphate - 5.84ppm
• Magnesium - 3.84ppm

Which means, in total, I'm adding in a weekly basis:

• Nitrate - 55.92ppm (2.8x recommended dosage )
• Potassium - 42.48ppm (1.5x recommended dosage)
• Phosphate - 17.52ppm (5.84x recommended dosage)
  
• Magnesium - 11.52ppm (about right)

According to UKAPS - Dosing with dry salts the recomended weekly dosing:

• Nitrate (NO3) 20ppm per week
• Potassium (K) 30ppm per week
• Phosphate (PO4) 3ppm per week
• Magnesium (Mg) 10ppm per week

Which means I'm actually dosing way too much PO4 and NO3, a bit more than needed K and about the right amount of Mg.
I found out that the problem was low CO2, but I'm still a bit concerned about the excess nitrate and phosphate.