# Mixing up EI ferts



## Surya (21 Jan 2019)

I've been using Aquarium Plant Food EI starter kit for about 4 months and am happy with it. But as my tank is 240l, I get through it quite quickly and find mixing it up rather tedious. I wondered about the following:

1. Can I mix up double concentration and dose half?

2. Do I really have to use boiled and cooled water? Can I just use tap (I have soft water if that makes a difference), or boiled but not cooled?

I did email APF with these questions a couple of weeks ago but got no reply. 

Thanks in advance!


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## dw1305 (21 Jan 2019)

Hi all,





Surya said:


> Can I mix up double concentration and dose half?


You can as long as you haven't reached the solubility limit of the salts. Try it and as long as there isn't any precipitation you are good. 





Surya said:


> Can I just use tap (I have soft water if that makes a difference)


Tap water should be fine, same applies as for the "double strength", as long as you don't get precipitates formed things are fine. 

cheers Darrel


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## Edvet (21 Jan 2019)

I scoop several teaspoons of ferts in a measuring can, add hot water from the top, stir and add to the sump. With a large tank this could be sometning for you, if you have the right size scoop.


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## Surya (21 Jan 2019)

Thanks both! I'd already boiled the water this time so made up a double strength solution with it - there is no precipitate so that seems fine. Next time I'll try it with plain tap water.


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## Kalum (21 Jan 2019)

Or make up a bigger batch (bigger container) so it'll last say a month or 2 and all you'll need to do is to decant into your smaller bottle for daily dosing


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## Surya (21 Jan 2019)

Kalum said:


> Or make up a bigger batch (bigger container) so it'll last say a month or 2 and all you'll need to do is to decant into your smaller bottle for daily dosing



True... but then I'll need to buy and store a bigger container


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## Kalum (21 Jan 2019)

Empty 2 litre juice bottle would do


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## Surya (21 Jan 2019)

Oh now there's a good idea! Thanks


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## Lee iley (22 Jan 2019)

precipitate what does this mean? I am thinking of mixing my own ferts. With a 400 litre tank I go through a bottle tnc complete quickly. But never done it before so wouldn't know which ones to buy etc


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## dw1305 (22 Jan 2019)

Hi all, 





Lee iley said:


> precipitate what does this mean?


It just means that some of the ions (nutrients in a form that the plant can take up) have come out of solution and formed solid salts. 

You can think about like adding table salt (NaCl) to a glass of water, at first it will all go into solution (dissolve) as Na+ and Cl- ions, but as you add more salt eventually the solution will be saturated (no more ions can go into solution) and you will be able to see the un-dissolved salt crystals. 

If you added more water, that salt would start to dissolve. Exactly the same with the fertilisers, they are "soluble salts" and if you try and dissolve too large a volume of them, in too small a volume of water, they won't all go into solution.

Cheers Darrel


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## ian_m (22 Jan 2019)

1. If you don't use boiled and cooled water and use straight tape water some people report precipitate forming in the macro solution due to the calcium in hard water forming insoluble calcium phosphate (or sulphate ?). Some people use RO water to mix their EI mix, either make your own (expensive) or buy say 10l from local fish shop and use that.

2. I mix EI at 1 1/2 times strength, BUT I do find I get slight precipitation (not much) in the bottles as I assume I am clearly exceeding the solubility of one of the salts. I also see it precipitating out in my dosing pump & tubes. So maybe I should go back to 1x EI strength...one day. Plants grow well, so maybe one day....

Why not dose dry salts if tank is large ? Just dose x amount of teaspoons of each salt into the tank.

Some people mix up their dry salts in advance then place the correct daily dose in say 10ml (or smaller) sample pots (search Ebay, £6 for 50off) so they just empty the pot into the tank to get the correct dose. Easy.


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## Andrew Butler (22 Jan 2019)

ian_m said:


> Some people use RO water to mix their EI mix, either make your own (expensive) or buy say 10l from local fish shop and use that.


+1 on that, it's not worth running an RO just for this so buy it from a LFS.
I mix up 5L of each at a time.


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## dw1305 (22 Jan 2019)

Hi all, 





Surya said:


> Can I just use tap (I have soft water if that makes a difference), or boiled but not cooled?


I should have said that you can use the warm water, and that most salts are more soluble in warmer water. The exception to the solubility rules are the carbonates, and that is because their solubility is dependent upon dissolved CO2, and all gases are less soluble at warmer temperatures.

When we boil the water all of the (bi)carbonate will come out of solution as "scale", if we pour off, and strain, the boiling water we have removed all the <"temporary hardness"> (the carbonates), but you haven't changed the amount of calcium (Ca), it is still there as the dGH or "permanent hardness", the hardness that can't be removed by boiling.

If we let the water cool again, without straining out the "scale", the carbonates will just go back into solution as the water cools and atmospheric CO2 re-dissolves. 





ian_m said:


> use straight tape water some people report precipitate forming in the macro solution due to the calcium in hard water forming insoluble calcium phosphate (or sulphate ?)


Yes it is a combination of calcium (Ca), pH and (bi)carbonate that cause the problems in harder water.

For calcium, nearly all compounds insoluble, or very sparingly soluble in water. Some compounds are soluble in weak acids (like CaCO3), calcium sulphate (CaSO4.2H2O) has a solubility of ~2g in one litre, and calcium phosphate (Ca3(PO4)2) a solubility of about 0.2g in one litre.

For the micro solution at pH values above pH 7 you also have "spare" OH- ions (that is how pH is defined), and they will form insoluble compounds like <"iron hydroxides">, if you have carbonates you will also get insoluble <"iron carbonates">.

RO (or rain) water doesn't have any dissolved ions, so none of these issues occur.

Soft water doesn't have any carbonates (or calcium in the UK), so you've avoided those issues.

However, in the UK even soft water now has a high pH, due to added NaOH, but there aren't actually many OH- ions (because NaOH is a "strong base"), a so a small addition of a weak acid (<"like citric or acetic acid">)  will neutralise the OH- ions.

Acids are "H+ ion donors" and bases are "H+ ion acceptors", in this case we only need to add as many H+ as there are OH- ions (to form H2O) and get back to the neutral pH7.

cheers Darrel


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## Surya (22 Jan 2019)

Wow, thanks so much for the detailed replies! Such an education being on here. Appreciate you all taking the time.


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