# Mixing Powedred fertilisers in a single stock solution



## ed seeley (Dec 1, 2006)

*Mixing Powdered fertilisers in a single stock solution*

I'm looking for abit of advice...

I have just bought some dry fertilisers with a view to making up my own version of a commercial fertiliser.
I have FeSO4, KSO4 and Trace Elements containing Boron, Copper, Iron, Manganese, Molybdenum and Zinc.
From what information i have, i have a rough idea of the sorts of quantities i will need to mix together to get a 'all-in-one', but any advice would be gratefully received.

I am also very unsure as to whether these compounds will be able to be mixed into one single solution without some things precipitating out of solution. What will their shelf-life be and should i keep them in the fridge?

Will i be ok to dose weekly, or should i dose them twice weekly or daily?

Are there any other things i should be dosing? (NB i don't want to dose Nitrate or Phosphate yet as i have only just got BGA under control and have a high stocking (for a planted tank) of fish)

Any advice on all/any of these things will be gratefully received!!!


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## Edward (May 25, 2004)

I wish it was possible.


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## HeyPK (Jan 23, 2004)

FeSO4 is going to get oxidized and change from ferrous to ferric iron and precipitate out in insoluble ferric compounds even if kept by itself. If these precipitates get into the gravel with mulm and the O2 content gets low, iron will be reduced and will become soluble again. I would keep FeSO4 by itself. It is not very good if you are trying to provide iron by way of the water column. 

The K2SO4 can be kept with the trace element mixture, but the iron is also probably going to precipitate out of the mix unless it is chelated (held in solution by being attached to an organic molecule). If it is listed as iron EDTA, it is chelated, but iron EDTA is broken down by light. Iron DPTA is better than iron EDTA because it is much less sensitive to light. 

Rooted aquatic plants can get precipitated iron from the substrate provided there is some organic matter in there and O2 content gets low and the iron gets reduced and solubilized.


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## ed seeley (Dec 1, 2006)

HeyPK said:


> FeSO4 is going to get oxidized and change from ferrous to ferric iron and precipitate out in insoluble ferric compounds even if kept by itself. If these precipitates get into the gravel with mulm and the O2 content gets low, iron will be reduced and will become soluble again. I would keep FeSO4 by itself. It is not very good if you are trying to provide iron by way of the water column.
> 
> The K2SO4 can be kept with the trace element mixture, but the iron is also probably going to precipitate out of the mix unless it is chelated (held in solution by being attached to an organic molecule). If it is listed as iron EDTA, it is chelated, but iron EDTA is broken down by light. Iron DPTA is better than iron EDTA because it is much less sensitive to light.
> 
> Rooted aquatic plants can get precipitated iron from the substrate provided there is some organic matter in there and O2 content gets low and the iron gets reduced and solubilized.


So would i be able to mix the powdered fertilisers into a mix and keep that as a dry powder and add the necessary quantity to the tank? I am trying to make adding the fertilisers i need as accurate as possible, while also keeping it convenient.

Can i make the separate chemicals up into solutions or will this be as bad for the iron precipitating? I have three tanks i am intending to dose with the same basic stock mixture. These are a 60litre, 100l and 140l. I am looking for any easy way to dose the dry fertilisers.

The Iron sulphate i have does not have any mention of being chelated. I assume this means it will need to be added on a very little and relatively often basis then as it will not remain in solution?
They recomend adding it straight to the tank and suggest 0.5grams per 100l to give a level of 1ppm (though obviously this will depend on what the level was before!)

Sorry if these are rather basic questions to you all, but I haven't messed about with this sort of thing since A-Level chemistry! (My Genetics degree was a piece of cake in comparison!)


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## wiste (Feb 10, 2006)

> So would i be able to mix the powdered fertilisers into a mix and keep that as a dry powder and add the necessary quantity to the tank?


I would avoid mixing dry chemicals. Although unlikely, you could create a volatile mixture.



> Can i make the separate chemicals up into solutions or will this be as bad for the iron precipitating?


Yes, you can make up separate solutions but do not mix the mircos and the macros.
Even if you do not use the PPS system, I have found the solutions that are described helpful.
These solutions do not exceed the maximum solubility of the chemicals for the prescribed amount of water. PPS described here (the link is also in Edwards signature above):
http://www.aquaticplantcentral.com/forumapc/science-of-fertilizing/4241-pps-perpetual-preservation-system-new-tables.html


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## ed seeley (Dec 1, 2006)

So basically dosing with these dry fertilisers is going to be a complete pain in the arse and i should have bought a commercial complete fertiliser that contained the things i wanted to add?


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## AaronT (Apr 26, 2004)

You might contact Greg Watson of Aquarium Plants, Aquatic Plants, Planted Aquariums, and Aquarium Plant Fertilizer to see if he can help you out. He's selling a similar product, though he doesn't do so for profit so I suspect he'd share his secrets.


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## ed seeley (Dec 1, 2006)

Many thanks for that link.

That website details doing almost exactly what i was intending! Mixing up a single solution from PPDM powders! They call it the Conlin Sears Formula, which i'm sure you are all familiar with. Now i see they don't add Iron sulphate to the mixture, probably because of it precipitating out, but they do mix trace minerals and add potassium sulphate, plus magnesium sulphate and potassium nitrate.

Can't i follow their lead and just leave out the MgSO4 and KNO3?

I will dose the iron separately and directly to the tank if i find it necessary, though i didn't realise when i bought the powders that the trace minerals contain 8.2% chelated iron!

Have i completely mis-read the information on this site or can i now do what i had originally intended to do?


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## AaronT (Apr 26, 2004)

Ed,

Yes, most people mix the nitrate / phosphate solution as a separate 'macro' fertilizer solution. Dosing the iron separately is also a good idea for the reason you stated; it precipitates out otherwise.


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## ed seeley (Dec 1, 2006)

AaronT said:


> Ed,
> 
> Yes, most people mix the nitrate / phosphate solution as a separate 'macro' fertilizer solution. Dosing the iron separately is also a good idea for the reason you stated; it precipitates out otherwise.


So there's nothing stopping me from doing what i had intended, minus the FeSO4? Or adding macros to the mix in the right proportions if i want to start adding them too? (I understand people do keep them separate for accuracy/ease of use but CAN u mix them?)
Do you guys keep solutions in the fridge to extend their life / stop bacterial/algal growth?
Will RO water be ok to mix up solutions, rather than distilled?
Should i dose small amounts daily, or larger amounts weekly/bi-weekly?

Sorry for all the questions, i just seems to get lots of conflicting advice!


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## Mud Pie Mama (Jul 30, 2006)

The PMDD formula which has the trace elements mixed together does NOT have any phosphate. Now-a-days most aqua gardeners are finding better success adding this element into their tanks. 'P' kept up to the proper dosing rates helps to keep GSA (green spot algae) under control.

Phosphorus is the 'P' in the NPK. NPK is the order mandated on every bag of fertilizers sold in the USA. These three main - MACRO - nutrients are always: Nitrogen, Phosphorus, Potassium.

However it is this phophorus when mixed in together with the Iron that causes cloudiness in tanks because these two interact badly when mixed together in the small storage bottles causing precipitation. Therefore the PMDD formula can work because it omits (leaves out) the phosphorus. 

Therefore now most folks are keeping a minimum of TWO solutions in two separate bottles. Traces w/ iron is one bottle; then all the Macros - NPK - are mixed in their own seperate bottle.

Consistancy is the best for the plants; smaller more frequent dosing... tri-weekly, (some, {me too} do daily)....is much better than just once weekly. Yet, if your dealing with a low light, slow growth tank once weekly dosing can work. With high light and supplemental CO2 - NOT! If you are maximizing the plant growth with strong light and injected CO2 it becomes very important to supply all the needed nutrients at all times.

I think this is one reason I've grown to love this hobby -- I relax and lower my blood pressure by watching the fish swim so elegantly and graceful. BUT at the same time I'm challenging myself and EXERCISING MY BRAIN trying to understand my systems and get them smoothly running!!!!



PSSS.
Anyone elsa mizz spell check az mucha az mi?


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## ed seeley (Dec 1, 2006)

Thanks for that, I was kinda thinking daily dosing would be best.
From what you've said, I may try adding the iron to the trace and K2SO4 if i find i need to add it regularly, i can always stop if i see precipitation! To start off with i'll keep it separate and add to the tank as a powder.


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## AaronT (Apr 26, 2004)

I would add iron to the trace mix and keep it separate as you said. That way you can adjust the macro and micro dosing for more than one tank if necessary. RO water should work just fine for mixing solutions. I never bothered to put mine in the fridge. I only mix up about 500 mls at a time though.


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## ed seeley (Dec 1, 2006)

AaronT said:


> I would add iron to the trace mix and keep it separate as you said. That way you can adjust the macro and micro dosing for more than one tank if necessary. RO water should work just fine for mixing solutions. I never bothered to put mine in the fridge. I only mix up about 500 mls at a time though.


Cheers Aaron,
The trace mix has 8.2% iron anyway, but i have a number of greedy plants so thought i might need more; not so sure now which is why i'm going to leave it to start with and add the Iron Sulphate straight to the tanks if needed.
500ml is exactly the kind of quantity i am going to mix up at a time, i might play it safe though and keep the majority in the fridge anyway! Can't hurt!
I've worked out the concentration i need to add so that one daily dose of 10ml will give me the required dose of K2SO4 and Trace in one go, though i will probably dose less than half this to start with and only build up if everything is ok.


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## AaronT (Apr 26, 2004)

Yeah, if you're are keeping stems (they tend to be the "greedy plants") then you'll definitely want to add extra iron.


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## ed seeley (Dec 1, 2006)

Got lots of cabomba piauhyensis, C.australis and Myacca fluviatilis. But apart from that it's the Nymphaea and huge Echinodorus cordifolius and Echinodorus x osiris that i was thinking about needing the nutrients!

Decided to start off with that i am going to add enough K2SO4 to add 2.5ppm per day and half the recommended dose of trace (as they quantities they recommend are to add 3times weekly). I'm going to look next at adding Mg to the mixture next as i use RO water with the minimum of RO right to re-minleralise it.

If that concentration doesn't trigger any adverse reactions i will up the dosage, but i think that will cover the needs for now!

Iron i will add weekly, i think, at 0.5 grams per in my 140l tank. This will only be tried as an experiment and i may do it once and then leave it for a while, then try again! Very cautious as i have been warned about the strength of Iron Sulphate!


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