# Any ferts not recommended to be added on the same day and/or together?



## Piscesgirl (Feb 25, 2004)

I really am not much of a fertilizer -- the times I think to add ferts are during water changes. Are there any that shouldn't be added on the same day/same time? Generally I just use Flourish, and some Potassium Sulfate (have Potassium Nitrate and Potassium Phosphate as well but usually use the Sulfate). I have a number of liquid ferts (such at Kent Botanica Grow) that I add on occasion. No method to my madness. 

Anyway, any that are NOT recommended to be added at the same time? 

Thank you :smile:


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## John P. (Nov 24, 2004)

Dose macros & micros on different days.


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## Piscesgirl (Feb 25, 2004)

Is that just a rule of thumb or are there some that interfere with each other?


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## John P. (Nov 24, 2004)

May cause cloudiness ... I don't recall the explanation/reason why.


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## bharada (Apr 17, 2004)

You may experience a white haze in the water if you does phosphate (PO4) and iron on the same day. It takes several hours to clear. I haven't experienced any issues other than that .


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## dennis (Mar 1, 2004)

Recent readings for another topic have made me realize that many of th nutrients we add have different charges. Many of the trace nutrients: Fe, K, Mg, Ca, etc all have positive+ charges while many of the macros, NO3, SO4 have negative charges-. I am not sure about PO4 but hazard a guess that it is negative also. Add opposites together, like magnets, and - may attract +. I know PO4 and Fe, especially in higher light, can bind to form FePO4, a fairly stable and insoluble compound that the plants can't use. I believe that bacteria, fungi and some chemical situations that happen in the substrate can break the bond and allow the nutrients to be used by the plants.

I may be wrong with some/all of this as I am just regurgitating info I recently read. Please correct me if I am wrong.


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## BigFoot (Jan 3, 2005)

Just my experience . I got hard water when i dose the flourish i would get the white haze also. Sense then i switch to dry ferts and no more white haze.I think the hard water and the ferrous iron to don't get along for what reason i have no clue of. Now its great to be able to put all ferts in everyday and not get the white devil.


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## Piscesgirl (Feb 25, 2004)

Thanks folks -- so it really just seems to be the Fe that causes problems?


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## titan97 (Feb 14, 2005)

Iron tends to form many insoluble compounds in the pH range we normally keep our aquariums. Some of them are completely insoluble, others are semi-soluble. The lower the pH, generally, the less problems you will have with Fe compounds. By lower pH, I am referring to pH's of less than 5 or so. I realize this is unacceptable to most fish (and perhaps plants). Dennis is right that cations (positive) and anions (negative) will combine and precipitate (the white haze you see), but only if the product is insoluble or semi-soluble in water. All nitrates are soluble, so FeNO3 is not your culprit for white hazy water. I would imagine that any white haze you see is due to FeSO4, FeSO4, or perhaps even FeCO3/FeHCO3. I don't have my solubility table in front of me, and I'm too lazy too Google it right now. 
If you have hard water or high nutrient concentrations, you may want to slowly add any Fe-containing ferts. If this doesn't work, we can then look at whatever else is in your fert solution.
Also, please excuse my unbalanced compounds. I know that NO3 is -1, PO4 is -3, Fe is normally +2 or +3, etc. For clarity's sake, I've omitted the correct subscripts for the compounds.

-Dustin


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## Piscesgirl (Feb 25, 2004)

I actually don't have any haziness, but I also don't add Fe. I was only looking for recommendations as to what things I shouldn't add together, a kind of general recommendation to use as a guideline.


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## SAWALLACE (Dec 24, 2004)

dennis said:


> Many of the trace nutrients: Fe, K, Mg, Ca, etc all have positive+ charges while many of the macros, NO3, SO4 have negative charges-. Add opposites together, like magnets, and - may attract +. I know PO4 and Fe, especially in higher light, can bind to form FePO4, a fairly stable and insoluble compound that the plants can't use. I believe that bacteria, fungi and some chemical situations that happen in the substrate can break the bond and allow the nutrients to be used by the plants.


How do you avoid this? There are always macros and micros present in the water column, wouldn't they bind no matter what?



titan97 said:


> you may want to slowly add any Fe-containing ferts.


Why does this make a difference?

...I'm just trying to understand


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## titan97 (Feb 14, 2005)

Compounds that are semi-soluble are in equilibrium between their solid and dissolved forms. Adding ferts slowly allows them to diffuse into the water column so that you don't get a portion of the tank with a relatively high concentration of the fert. This should (in theory) help reduce haziness caused by precipitation. It is probably a stretch in practice, but who knows how effective it might be.

And yes, all the ferts are present in the water column. Some of them will combine and possibly precipitate. However, remember that the plants are (hopefully) consuming some of them all the time, which drives the equilibrium reaction towards one direction (towards the side of the equation with the 2 separate compounds, not the bonded-molecule). You also have to remember that there were ferts in your tank before you started dosing (unless you used RO/DI water, which is another topic). So, your Fe, PO4, Ca, etc have already set up their relative equilibriums. Once you start adding you ferts, you change the equilibrium, but it is still there. 

I realize that this is somewhat off-topic, but I am hoping that some non-chemists out there on the IntarWeb gain some knowledge about their tanks, and have more understanding of the why and how ferts work.

But to answer the original question as best and quickly as I can:

You should have no problems dosing micros and macros on the same day. However, if you have haziness, you might want to adjust your schedule. 

Hmm, and I wonder if dosing on the same day will affect the osmotic pressure enough to stress the fish . . . .? I doubt that we are adding enough minerals to mess with the TDS that much, but . . .. 

-Dustin


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## baj (Nov 2, 2004)

titan97 said:


> Hmm, and I wonder if dosing on the same day will affect the osmotic pressure enough to stress the fish . . . .? I doubt that we are adding enough minerals to mess with the TDS that much, but . . ..
> 
> -Dustin


Unlikely


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## Error (Apr 16, 2004)

Generally the thought is to avoid dosing iron and PO4 together. Lots of things push iron out of the water column as it is (i.e. precipitation due to light and other free anions), so PO4 just adds to the list.

I wonder if the "stabilized" Flourish iron is less prone to precipitation.


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## Rolo (May 12, 2004)

Yep, I believe it is just Fe and Phosphate that there is a concern about. Not all elements bind and form precipitates SaWallace, just depends which ones. Some are soluble, some not...iron phosphate is one of those that really are not.

BTW, this concern doesn't _fully_ make sense to me. The iron we use is chelated, and the purpose of the chelate being to protect it from reacting and becoming unavailable to plants, is it not? Sounds like this is right up Tom's alley. ;-)


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## titan97 (Feb 14, 2005)

Even chelated molecules are in equilibrium with their non-chelated versions. It just may be that the forces between the chelatee and chelator are strong enough to keep the majority of the (in this case) Fe bound up and unavailable for the (in this case) PO4. Otherwise, if the bond was so strong that the Fe could never leave, it would be unavailable to the plants as well. 
Also, I'm sure that the forces binding FePO4 together are stronger than the attraction between the Fe and it's chelator. It is for this reason that it is more beneficial to have the Fe locked up in the chelated form than in the PO4 compound.

-Dustin


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## plantbrain (Jan 23, 2004)

The type of chelator plays a role.

Also, you can add micros at night and then add macros in the morning also.
A few hours of separation is all that's needed. 

Main thing is to dose so that you need less traces, macro's are cheap.
Try using TMG vs Flourish. Give things no less than 3 weeks before judging.

Regards, 
Tom Barr


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## Raul-7 (Feb 4, 2004)

Then that means automated-dosers are almost useless when dosing macros and micros together? I wonder if Gian has had problems with this since he doses micros and macros together.


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