K, N and plant growth

[wee]

Yesterday I dissolved two teaspoons of K2SO4 and MgSO4 into my 4x2x2 (about 300+ litres). Shortly after that Dr Mallick returned my call. From his description, I added almost 3 times the recommended dosage.[] Fear of disaster, I followed his suggestion of doing a half tank water change. (that’s why didn’t make it to Teo’s planting session.)

His instruction: dissolve 10gram (about 2 teaspoons) of K2SO4 into 1 litre of water (this will be 1% solution). Dosage for this prepared solution is: 10ml for every 10 litres of tank water. Same for MgSO4.

Didn’t check with him on the danger of over dosage. Any idea?

Thanks.

[CK Yeo]

?? 20g/300l = 0.066g/l = 66 mg/l = 66 ppm
This concentration is fine for K... but a bit high for Mg.

Excess K is harmless. Overdose Mg will block uptake of other nutrients.

[chrissia]

Hi ck,

Could u elaborate more on the issue of Mg blocking nutrient uptake.

Cos 3 mths back, i was dosing Mg n k every week for a mth. Then i rescape the whole tank and BAM the whole tank is dead. Nothing grows.

Now after 2 mths, things r looking much better. I would say 60% of my plants r growing.

Could overdosing of Mg or Lo salt be the cause of my problem? Would like to know more about Mg limiting nutrient uptake if you have the time to share.

Thanks.

[vinz]

CK,

Read it again... it's 2 tsp into 1 litre to make 1% solution which is dosed at 10ml per 10l.

Wee

I think Dr M's solution only raises ~5.5ppm K and ~1ppm of Mg. Your original calculations are correct for raising ~17ppm K and ~5ppm Mg. So it depends on what how much you want to dose.

I dose 20ppm of K once a week. My GH is high so I don't dose Mg.

[vinz]

Chris,

Did you check your GH or observe Mg deficiency before dosing Mg?

[CK Yeo]

Vinz,

paiseh...must be too early... thanks for pointing that out.
It was supposed to be 10g/300L so, 0.033g/L or 33ppm MgSO4. MgSO4.7H2O is 9.74% Mg, so should be 3.2ppm of Mg. Should be fine... so Wee, you missed the gathering for nothing.

According to Dr Mallick's dosage:

10g/L diluted 1000X (10ml to 10L), you get 10ppm of K2SO4. K2SO4 is 44.87% K, so you will get 4.487ppm.

Mg, according to Dr Mallick's dosing will be 2.02ppm. Correct?

chrissia, we love our plants to death.
Mg blocks Ca when excess, and the imbalance between K, Mg and Ca cause stunting and stuff like that... I dun have a hard number to say how much is "excess", but why push your luck? Salt (NaCl) on the other hand... It is not a essential element in plants. It is considered toxic to plants. Many plants tolerate to various extend. Some add salt to their tanks for whatever reasons with no problems, but YMMV.

ck

[chrissia]

Vinz,

No test kit for GH. Don't think have Mg deficiency. I added 5 ml of Mg every week after water change for a month. Experimenting that time. Now I know the answer. hahaha..... Thot it isn't harmful wif 5 ml or is it?

CK,

Thanks for the explanation. I add lo salt to boost K. What's YMMV? The problems with my plants back then was that they either turn black or melt or juz refuse to grow.

Now I have one plant with two different leaf development in my tank. hahahaha.... dun know what is wrong (the water or substrate)? Headache. Headache.

[vinz]

CK, I get 0.99ppm Mg with Chuck Gadd's calculator. You K calc is correct.

Hmmmm... high Mg block Ca... I have high GH, might explain why my nanas are showing Ca deficiency... but only my nanas that are not planted in gravel. All other plants seem fine.

Chris, I was more concerned that you're ODing Mg.

[CK Yeo]

Opps... forgot about the 7H2O MgSO2, so 0.99 is correct. Sheesh, I must be getting old...

[tawauboy]

so if we're using dr mallick's mgso4, which is 98% pure, then the dosage will be half compared to epsom salt.
is this right?

[bclee]

Dr. Mallick's MgSO4 is also in crystal form which mean they are in the form of MgSO4.7H2O. So the same dosage applies.

BC

[tawauboy]

if not wrong, dr mallick's mgso4 is a whitish powder while epsom salt is a opaque crystal. they are the same?

[bclee]

The one I've got from Dr. Mallick's is crystals.

BC

[wee]

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On 10/9/2002 1:31:30 PM

The one I've got from Dr. Mallick's is crystals.

BC
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yes, the mgso4 i bought last week from Dr Mallick is also crystals.

[tawauboy]

got to go home and check my bottle again.

[DEA]

lol
just grind the crystals up and you'll get white powder
the h20 is water of crystallisation cannot see one

[tawauboy]

eyesight not good.
my bottle is also crystals.