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Nutrient deficiency?

2178 Views 8 Replies 3 Participants Last post by  plantbrain
Hi everyone, last week in my 15 gallon i started fertlizing (experimenting with Tom Barr estimated method). Half a teaspoon of potassium sulphate & epsom salt, about 7ppm of potassium nitrate per week and 3 drops of PMDD mix (minus the nitrate) per day. the water here is very soft. According to the local water company, the tap water has an average hardness (GH) of 21 mg/L (1.2 dH) and and average alkalinity (KH) of 11 mg/L (0.6 dH). ph is approx at 7.
i have 30 watts of light from a NEC triphosphor bulb and Soil/ gravel substrate. no co2 supplement at the moment.
well a few days after a started fertilizing some leaves of my hygro polysperma went kinda white and some were bronze and developed patches of green but the leaves of other plants stayed basically the same colour. also growth has stopped and the leaves of hygro polysperma and difformis appear to be wilting. growth was better before i started this fertilising regimen.
does anyone know wat the problem is?
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The problem is probably the Potassium or the Magnesium in your PMDD-mix that inhibit Calcium-uptake/usage. Curly leaves is a sign of Calcium-deficiency.

You get 4.42 ppm of K from the KNO3-dosage (7 ppm of NO3 from KNO3 yields 4.42 ppm of K) and also 23.7 ppm of K from the K2SO4-dosage.

That means 28.12 ppm of K which is quite some K.
hi defdac, thanx for the reply

what you say seems very possible.
so what do u advise me to do? reduce potassium ferts or start fertilising calcium?
A few things here:

Non CO2
Don't do water changes and don't add nutrients, use fish to do this and add a rich substrate. Add some CaCO3 finely ground to the gravel or filter etc.

Add some floating plants etc.

The methods are much different for successful non CO2 planted tanks than CO2 enriched methods.

The rate/amount of nutrients removed are greatly enhanced by CO2 additions.

Tom Barr
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hi Tom, what sources of calcium carbonate should i be using? if i add it to my tank, would it stay there forever or would it dissolve and need to be constantly be replenished?
It will slowly dissolve, might take a long time. But with non CO2 methods, the rate is okay.
CaCO3=>calcite , aragonite etc.
The finer ground, the faster it will dissolve
Dolomite also works, it has both Ca, Mg and CO3.

Tom Barr
if i were to start adding co2, would i still be adding the CaCO3?
and would u happen to have any recommendations of dosing? how much, how often, add more during water changes?

thanx heaps
You can add a little bag to the filter of fine ground dolomite CaMg(CO3)2 or CaCO3.

For CO2 methods:
You will be better off using something like Baking soda for KH
And CaCl2/MgSO4 for GH
These both dissolve rapidly and allow you to dial in a certain GH or KH.
You can also use SeaChem Equilbirium for GH.
Generally 3 degrees or so is good range, ~50ppm or mg/L.

You will do large water changes and dose accordingly.
CaMg(CO3)2 and CaCO3 take too long to get the levels correct for CO2 tank methods and large frequent water changes.
If all you need is a little GH/KH buffer, then CaCO3 etc is fine.
But you need more so that might not be the best for you if you go CO2.

Non CO2 tanks you generally do not do any water changes if you have set it up properly except once every 6-24 months etc.

Tom Barr
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