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Is Sulphate of Potash safe to use in aquariums?

Akmaliano

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Hi all,It look s more like an iron (Fe) deficiency on that photo.

Are the new leaves bigger and greener? if they aren't? <"I'd try a different chelator">.

cheers Darrel
Thank you Darrel. That's more in line with what I've been suspecting. I've been dosing additional DTPA 7% chelated iron for a while with no success and from further research realised that a lack of Mg was the real culprit since apparently its lack prevents a proper uptake of iron? So I've started dosing epsom salts since recently and things appear to be improving (still a bit too early though).
One thing that annoys me is that nowhere in the mainstream information about EI do they mention that in almost every case hobbyists based in the UK should add extra Mg on top of the usual Macro solution as our water here is calcium rich but magnesium poor, and a lack of the latter causes much trouble
 

Akmaliano

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Are the new leaves bigger and greener? if they aren't? <"I'd try a different chelator">.

cheers Darrel
Yes, new growth seems to be much better.
Also thanks for posting the link to our previous discussion in this topic, I was actually looking for it. In there you too did mention that in the uk we almost always have to add extra Mg but it's a shame that the most of the sources of EI information don't mention that (unless I've missed it somewhere!)
 

ian_m

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(unless I've missed it somewhere!)
I think you missed it. The original EI research used RO water, with none or limited hardness added, so as to exclude any issues due to water supply quality. Some US sites, though do quote you don't need to add MgSO4 if using tap water, as in US hardness is often due to Mg rather than Ca. Not seen this recommended in UK, most stuff I have seen in UK quote the EI values of MgSO4.

Adding extra MgSO4 won't cause issues.
 

Akmaliano

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Not seen this recommended in UK, most stuff I have seen in UK quote the EI values of MgSO4.

Exactly. IMHO, EI dosing standards for the UK should be updated to specifically recommend additional MgSO4 to reflect the fact that our water simply does not have enough of it and its lack causes so much trouble
 

dw1305

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Hi all,
I've been dosing additional DTPA 7% chelated iron for a while with no success and from further research realised that a lack of Mg was the real culprit since apparently its lack prevents a proper uptake of iron? So I've started dosing epsom salts since recently and things appear to be improving
Yes, it is the high levels of calcium (Ca++) ions that interferes with the uptake of magnesium (Mg++) and iron (Fe+++) ions. Because both magnesium and iron are required for the synthesis of chlorophyll, the lack of either leads to chlorosis.

Iron is a bit different to the macro-nutrients, it is similar to the other micro-nutrients (like zinc (Zn), copper (Cu), boron (B) ) in that it is essential for plant growth, but at the same time, iron is highly reactive and toxic via the <"Fenton reaction">. This means that plants have to control iron uptake, and react to both iron deficiency and iron excess.

If you have a plant like Hornwort (Ceratophyllum demersum), or Vallisneria spp., they come from alkaline, high calcium environments where iron is always in short supply. They are very efficient at sequestering iron, they aren't going to show deficiency symptoms unless there really are no iron ions in solution or in the rhizosphere. Against that they may struggle in soft water, where iron toxicity could be an issue.

If you have a plant that naturally grows in acidic, very soft, water (<"Tonina"> etc.) it will have mechanisms that efficiently exclude iron, because it is always plant available and toxicity is much more of a potential issue, <"Rotala rotundifolia"> looks like another plant which is quick to show iron deficiency symptoms.These may relate to the dKH and pH more than the actual amounts of divalent cations (dGH).

Most plants will be somewhere in the middle, and capable of growing along in a wide range of water types.

cheers Darrel
 

dw1305

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Hi all,
I am running out of K2SO4 and I can use Amazon product as a direct replacement (so the same amounts)? Is there anything else mixed with it? Will it be soluable just like the stuff I have from Aquarium Plant Food?

Yes direct replacement, same chemical, both K2SO4 and highly soluble.

If you dose it as dry salts etc into the tank it should be fine. If you run a dosing pump you could potentially have problems because of the lesser level of purity of this ordinary "fertiliser" grade salt.

cheers Darrel
 

sparkyweasel

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Have you noticed the price?
£7.95 for one box including delivery, or you can have two for £21.14 plus £2.49 delivery. :confused:
 

jameson_uk

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Hi all,

Yes direct replacement, same chemical, both K2SO4 and highly soluble.

If you dose it as dry salts etc into the tank it should be fine. If you run a dosing pump you could potentially have problems because of the lesser level of purity of this ordinary "fertiliser" grade salt.

cheers Darrel
What about in a mixed solution? I am currently making an all-in-one liquid (New Fert Time and Confused... (Sulphur Levels?))
 

dw1305

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Hi all,
What about in a mixed solution?
Calcium sulphate (CaSO4.2H2O) is "sparingly soluble", but that isn't an issue once the fertiliser mix is diluted in the tank water. If you don't have problems at the moment it should be fine.

The only issue would be that if you had a dosing pump there might be insoluble impurities that could block the peristaltic tubing.

cheers Darrel
 

dw1305

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Hi all,
how do we get from K2S04 to CaSO4.H20 ?
You have the SO4-- ion (from the dissolution of K2SO4). Potentially that will form less soluble sulphate compounds, if there are suitable ions in solution.

Most <"sulphate compounds are soluble">, but calcium sulphate is only "sparingly soluble", and as soon as you exceed the solubility limit of CaSO4.2H2O it will precipitate out of solution.

If you had water with low dGH you might add the soluble calcium choride (CaCl2.2H2O) to the "all in one mix", but in that case if you added a soluble sulphate compound (like "Epsom Salts" (MgSO4.7H2O)) insoluble CaSO4.2H2O will form.

Because you have hard tap water, I assumed that you would add calcium just from the calcium carbonate in your tap water.

cheers Darrel
 

jameson_uk

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You have the SO4-- ion (from the dissolution of K2SO4). Potentially that will form less soluble sulphate compounds, if there are suitable ions in solution.

Most <"sulphate compounds are soluble">, but calcium sulphate is only "sparingly soluble", and as soon as you exceed the solubility limit of CaSO4.2H2O it will precipitate out of solution.

If you had water with low dGH you might add the soluble calcium choride (CaCl2.2H2O) to the "all in one mix", but in that case if you added a soluble sulphate compound (like "Epsom Salts" (MgSO4.7H2O)) insoluble CaSO4.2H2O will form.

Because you have hard tap water, I assumed that you would add calcium just from the calcium carbonate in your tap water.
Simpler than I thought then :D

So my worries about SO4 (New Fert Time and Confused... (Sulphur Levels?)) were probably even less relevant as the extra SO4 would potentially come out of solution anyway in combination of with the calcium.

Out of interest, could this this actually affect dGH? If you added a lot of SO4 could that combine with the calcium and actually reduce the hardness.
 
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