Why exactly do we dose EI on alternate days? . . .

Wookii

Member
Joined
13 Nov 2019
Messages
1,008
Location
Nottingham
I've never been able to find an accurate explanation for this.

I understand the need to store concentrated micro and macro mixes separately to try and avoid the iron and phosphate reaction and resulting precipitation (though of course there are techniques for AIO solutions that we are all aware of), but when dosing EI, there will (or should) always be a prevailing levels of PO4 in the water column, so why does it make any difference if we dose micros and macros on alternate days, vs everyday at half the alternate day dose?

I've read some people say that the iron/phosphate reaction can occur at tank level concentrations, and others say that is nonsense and in tank concentrations are too low for that to happen on any problematic scale. Even then, if the reaction does occur in tank, is that not an argument for ensuring each is topped up daily?

I appreciate it might be wise to wait an hour or so between the doses to allow thorough mixing of the first dose with the aquarium water, so does the alternate day dosing really just stem from convenience for manual dosing?

If so, as we are now in a world where electronic dosers are available to the masses for reasonable cost, would timed daily dosing not create better in tank stability than the alternate day dosing?
 
Last edited:

dw1305

Expert
Joined
7 Apr 2008
Messages
10,971
Location
nr Bath
Hi all,
If so, as we are now in a world where electronic dosers are available to the masses for reasonable cost, would timed daily dosing not create better in tank stability than the alternate day dosing?
Ideally you probably would dose every day if you wanted optimal plant growth.

In commercial tomato culture (<"using rockwool">) you feed twice a day, and tomato farming doesn't have a lot of margin, so that is usually a pretty good indication that this is the most efficient method.

My guess is that it doesn't make much practical difference for the micro (trace) elements, the plants just really require "some" rather than "none".

If you were confident that you weren't going to have a doser malfunction (that dumped lots of fertiliser in your tank) it would also open up the potential for using <"urea ( CO(NH₂)₂ ) as a nitrogen source">. As well as being <"very cheap"> (and <"not a potential explosive">) urea allows you to add nitrogen (N) on its own.

Even though phosphorus (P) is a macro-element plants need an order of magnitude less of it than they do carbon (C), nitrogen or potassium.

Because most phosphate compounds are insoluble in hard, oxygenated water many plant have adaptations that allow them to effectively scavenge any available PO4--- ions. It is a bit like the adaptation that allows Ceratophyllum demersum &Vallisneria spp etc. to use HCO3- as a carbon source.

cheers Darrel
 
Last edited:

Wookii

Member
Joined
13 Nov 2019
Messages
1,008
Location
Nottingham
Hi all, Ideally you probably would dose every day if you wanted optimal plant growth.

In commercial tomato culture (<"using rockwool">) you feed twice a day, and tomato farming doesn't have a lot of margin, so that is usually a pretty good indication that this is the most efficient method.

My guess is that it doesn't make much practical difference for the micro (trace) elements, the plants just really require "some" rather than "none".

If you were confident that you weren't going to have a doser malfunction (that dumped lots of fertiliser in your tank) it would also open up the potential for using <"urea ( CO(NH₂)₂ ) as a nitrogen source">. As well as being <"very cheap"> (and <"not a potential explosive">) urea allows you to add nitrogen (N) on its own.

Even though phosphorus (P) is a macro-element plants need an order of magnitude less of it than they do carbon (C), nitrogen or potassium.

Because most phosphate compounds are insoluble in hard, oxygenated water many plant have adaptations that allow them to effectively scavenge any available PO4--- ions. It is a bit like the adaptation that allows Ceratophyllum demersum &Vallisneria spp etc. to use HCO3- as a carbon source.

cheers Darrel

Thanks as always Darrel, great reply. What are your thoughts on the phosphate and iron reaction/precipitation at typical in-tank concentrations?
 

dw1305

Expert
Joined
7 Apr 2008
Messages
10,971
Location
nr Bath
Hi all,
What are your thoughts on the phosphate and iron reaction/precipitation at typical in-tank concentrations?
I'm pretty sure that some people have seen precipitation occur, possibly because they were adding iron gluconate etc . You really need @X3NiTH to comment, they are <"a proper chemist">.

In terms of iron (Fe) you could definitely get around any problems by adding a chelator that is more effective at higher pH levels. I like the <"pink tint"> approach, but I have a pretty <"laissez faire"> attitude to <"fertilisers etc">, and just want some plant growth.

cheers Darrel
 

sparkyweasel

Member
Joined
30 Jun 2011
Messages
1,502
EI was developed to be simple and foolproof. By specifying alternate dosing it removes the possibility of a problem that might occur in some tanks, depending on many variables. If you change it there's no certainty that you won't have any problem. That's not a reason for not trying it to see, but it's a reason for the original EI method advising the alternate day method which more or less guarantees success.
 

X3NiTH

Member
Joined
13 Apr 2014
Messages
1,014
You really need @X3NiTH to comment, they are <"a proper chemist">.

I wish, I don’t have single chemistry qualification to my name because I’m/was crap at maths and school was a bad place for me to learn, ‘too easily distracted’ was a bane on every single school report card that my father would punish me for which was cruel as he was exactly this way himself (himself crap at school but exceptionally brilliant in the things he took interest in), Too easily distracted’ is a horrible put down way to phrase ‘Interested in Everything’.

Now that I’ve humbled myself I hopefully can answer the question!

At standard doses for tank volume you should really only see precipitation if you were to dump the entirety of an Iron dose in one go into the water (brown/green clear liquid takes on a milky appearance), it would depend on how strongly bound the chelate was at the specific pH when it’s dosed, the effect would be localised and quickly stop visibly reacting with present phosphate as the total concentration of the iron becomes more dilute as it diffuses through the water column, you will lose some of the total iron but not all and if dosed everyday or every other day you are unlikely to end up with deficiencies (unless your mega dosing phosphate through extra added ferts or excess fish food).

If you do see milkiness when dosing iron it may be worth either diluting the concentrate further to reduce total concentration for the dose size or drip it in slowly using a doser (I dose @ 1ml per min and it goes in drop by drop, complete diffusion with no apparent precipitation).

I find there is Zero point in regular testing for total levels as long as they are going in regularly, you can test at the beginning to get an idea of the longevity of the chelate you are using for Iron at the pH levels you have in the tank.

I use mainly Gluconate and DTPA as Fe chelates as my pH is above neutral all the time, the gluconate can be gone quite quickly, I’ve read somewhere within an hour depending on how much light there is, I haven’t bothered to test for this because the plants should have scavenged what they need for the day before the main dose is all gone. The DTPA on the other hand constitutes one third of my blend and it’s half life is considerably longer than gluconate, When first testing the effect of this blend at above neutral pH I was detecting less than Half the total amount of Iron dosed for DTPA 24Hrs later (assumption that the gluconated chelate is 100% broken down). This shows that as soon as the chelate degrades the free Iron will react with whatever it can bind with and drop out of the water column, things it can turn into that make the Iron unavailable are Phosphates, Oxides and Carbonates, how much would depend on their total concentration in the receiving water (ending up amongst that brown floc at the bottom of the canister filter hopefully).

You’ll note that that having said all of the above I’ve not really considered plant uptake as an effect for loss of Iron from the water column only hoped for it, you can’t test for this without destruction of the plant so you are left with making observations that new growth is not pale and iron deficient (Darrells’ Duckweed Index will give you the fastest visual results for determining white new growth).

Takeaways are if you see precipitation takes steps to mitigate this by increasing the dosing time or dilute the concentration and dose more, if your out of pH range for your chelate then switch to one that is more suitable.

Dose Often!

:)
 

Luketendo

Member
Joined
25 Feb 2008
Messages
632
Location
Australia
Oddly enough the EI fert I mentioned on that other thread has everything mixed in all in one bottle, but still says dose every other day. I decided just to dose everyday instead since I don't want to be trying to remember if I dosed yesterday etc...
 

Zeus.

Member
Joined
1 Oct 2016
Messages
3,379
Location
Yorkshire,UK
Dose Often!

I even took this one step further with auto doser, why dose macros x3 week and Micros x3 a week ? there are seven days in the week. So I dose micros 4 times a week dosing less on micro day but the weekly total yield is the same. Plus with my tap water dosing Macros after WC seemed silly as my tap water with a 50% WC was putting in about 10 ppm NO3
 

Wookii

Member
Joined
13 Nov 2019
Messages
1,008
Location
Nottingham
Indeed @Zeus. - the Jebao doser I have can only do alternate days anyway, it doesn't have a weekly scheduler - so I dose every day, micros/macros on alternate days, essentially on a 14 day cycle. But then I do automated daily 25% water changes also, so it works well without any issues with water change timing.

It just really occurred to me, and was the purpose of this thread, if we're using an auto-doser, why are we doing alternate days - if thats a hang-over from manual dosing days - when we can schedule a dose whenever we like and achieve better consistency and stability of the nutrients in the water column.

Further to @X3NiTH 's excellent post above, I personally see no clouding at all in my tank when I dose micros, and I dose double PO4 in the macro mix to help keep GSA at bay, and also double Fe as I add DTPA to my micro mix. If we also consider that the dose usually goes in after the CO2 has kicked in, so the pH will have already dropped below pH 7.0 and remain there for the photo period, then I think there is little need to dose micros and macros on alternate days.

I will run a test this weekend and dose a full micros dose an hour after a full macro dose and see if I get any clouding in a still tank. If I don't then when I rescape in a couple of weeks I'll likely re-program the doser to dose both daily an hour apart.
 

Zeus.

Member
Joined
1 Oct 2016
Messages
3,379
Location
Yorkshire,UK
if we're using an auto-doser, why are we doing alternate days - if thats a hang-over from manual dosing days - when we can schedule a dose whenever we like and achieve better consistency and stability of the nutrients in the water column.

Yes I think it is a hangover from manual/dry dosing days. As it took effort. With an auto doser theres no effort needed once setup.

Just thinking about it and a cant think of a good reason why we cant dose Macros and Micros on the same day - say Macros at noon and Micros at midnight. This would take the little and often just one step further and should make for a more stable/balanced system.

Then if using an AOI fert and dosing x7 a week - why dose it all at once (if your auto doser allows) split it up into a few doses over the day !!! Makes sense after what @Z3NiTh posted
increasing the dosing time or dilute the concentration and dose more

Spreading the dose over the day is increasing dosing time
 

Zeus.

Member
Joined
1 Oct 2016
Messages
3,379
Location
Yorkshire,UK
Then if using an AOI fert and dosing x7 a week - why dose it all at once (if your auto doser allows) split it up into a few doses over the day !!!
Dont need to think about that one as its a 'no brainer' IMO

so was 10ml once a day (ignore the label 'macro' as its just a label)
1600768442716.png


Now 1ml x10 a day two hours apart
1600768562686.png


Think it will be better also as I am dosing Urea as the source of Nitrogen in this tank - little and often to very little more often
 

Geoffrey Rea

Global Moderator
Staff member
Joined
27 May 2017
Messages
988
Location
Cambridgeshire
Interesting. The takeaway from @X3NiTH ’s post that grabbed attention here was:


You’ll note that that having said all of the above I’ve not really considered plant uptake


Consider @X3NiTH to be very wise in this self observation. Taking things to their logical confusion is great theory but... what about your outcome?
Your plants are your end users, what remains in the water column, ascertained by any particular measurement at any single point in time, isn’t really useful in telling you how your end users are doing. Striving for consistency at all times? Why? What evidence exists to say this is superior compared to alternate day dosing of the full daily volume of either macro or micro nutrients at once for your plants?

Being blunt, the estimative index is drum roll.... estimative. Any argument based on the effectiveness of varying methods of nutrient deployment would have to consider the effectiveness of any single plant species to uptake nutrients. Or, just look at the plants or duckweed or [insert choice here]. Things that could be messing up your chi other than nutrient input; lighting, plant location within tank, flow, competing algae’s, human error.

All things considered instinct says it’s what you consistently do over the months that matters, rather than the chosen method day to day.

The glaring hole in the conversation here is what are you trying to influence?

Healthy growth? Fast growth? Slow growth? Particular plant form under specific lighting and nutrient availability?

If it’s simply growing plants without deficiencies in a simple and successful manner:


EI was developed to be simple and foolproof.

Each to their own. Eat twenty four small meals a day or three meals a day. Either way you won’t go hungry.

Also still waiting to see this massively iron deficient tank on UKAPS that is EI dosed with EDTA chelated iron. Every time, and I can’t stress this enough, every time a customer came in claiming iron deficiency it was either a) an incorrect deficiency guess or b) they messed up their mixing with phosphate and nitrate with their macro mix. Suffice to say I remain very skeptical that iron deficiency is prevalent in EI dosed tanks whether or not it is theorised that a majority of what is put in precipitates out amongst all the complex, largely untestable chemistry taking place in an aquarium.

Iron is and always will be a micro nutrient. EDTA, DPTA, EDDHA.... Try not dosing it at all for several weeks, take weekly photos. It will take an age for iron deficiency to appear across the entire tank, especially if you use tap water for water changes. Highly suspect ‘groupthink’ has more to do with aquarists obsessing about iron than any real empirical evidence.
 

Zeus.

Member
Joined
1 Oct 2016
Messages
3,379
Location
Yorkshire,UK
Hello,
This is one of those situations where we make life more complicated for ourselves with very little to show for it.

Iron is a micronutrient, which means the plant only needs microscopic amounts of iron. About one hour after you have dosed iron, the plant has already taken up it's fill. Of course it's easy to pummel the plant with more iron than it needs without any ill effects, but why bother? Why spend more money and effort for specialized chelation when it is already overkill with the less efficient chelated methods? I really doubt you will see any benefit.

A lot of this hand wringing over [insert your favorite chelator here] arises because for generations, people have misdiagnosed the basic deficiency of plants. They see yellowing of leaves and immediately assume it's due to lack of iron. There are even folks who spend their hard earned cash on [gasp] Iron Test Kits. In 99% of these cases, their tap water already had sufficient iron and the real deficiency is Nitrogen, but since everyone becomes hysterical at the mere thought of adding Nitrate, then one myth feeds another to create pandemonium.

My advice is to use the cheapest and/or the most convenient source of iron and simply carry on. If iron is present in your basic micronutrient mix, then just use that without worry.

Cheers,


Taking the plunge again, Modified my Macro/Micro dosing on 500l so they get Macros and Micros every four hours with a two hour delay between the the Macro and Micro dose with the same weekly yield in ppms

1600771530907.png
 

Wookii

Member
Joined
13 Nov 2019
Messages
1,008
Location
Nottingham
Interesting. The takeaway from @X3NiTH ’s post that grabbed attention here was:

Consider @X3NiTH to be very wise in this self observation. Taking things to their logical confusion is great theory but... what about your outcome?
Your plants are your end users, what remains in the water column, ascertained by any particular measurement at any single point in time, isn’t really useful in telling you how your end users are doing. Striving for consistency at all times? Why? What evidence exists to say this is superior compared to alternate day dosing of the full daily volume of either macro or micro nutrients at once for your plants?

Being blunt, the estimative index is drum roll.... estimative. Any argument based on the effectiveness of varying methods of nutrient deployment would have to consider the effectiveness of any single plant species to uptake nutrients. Or, just look at the plants or duckweed or [insert choice here]. Things that could be messing up your chi other than nutrient input; lighting, plant location within tank, flow, competing algae’s, human error.

All things considered instinct says it’s what you consistently do over the months that matters, rather than the chosen method day to day.

The glaring hole in the conversation here is what are you trying to influence?

Healthy growth? Fast growth? Slow growth? Particular plant form under specific lighting and nutrient availability?

Turning the question on its head though Geoff, what is the reason not to dose daily? What is the benefit of dosing alternate days instead, particularly if that involves more complicated doser set-up and programming? Surely, beyond anything else, dosing daily simply reduces the likelihood of any deficiency occurring since every photoperiod has all nutrients dosed just before.


If it’s simply growing plants without deficiencies in a simple and successful manner:

Each to their own. Eat twenty four small meals a day or three meals a day. Either way you won’t go hungry.

Also still waiting to see this massively iron deficient tank on UKAPS that is EI dosed with EDTA chelated iron. Every time, and I can’t stress this enough, every time a customer came in claiming iron deficiency it was either a) an incorrect deficiency guess or b) they messed up their mixing with phosphate and nitrate with their macro mix. Suffice to say I remain very skeptical that iron deficiency is prevalent in EI dosed tanks whether or not it is theorised that a majority of what is put in precipitates out amongst all the complex, largely untestable chemistry taking place in an aquarium.

Iron is and always will be a micro nutrient. EDTA, DPTA, EDDHA.... Try not dosing it at all for several weeks, take weekly photos. It will take an age for iron deficiency to appear across the entire tank, especially if you use tap water for water changes. Highly suspect ‘groupthink’ has more to do with aquarists obsessing about iron than any real empirical evidence.

Your experience of all this is obviously far greater than mine, or indeed many others on here, but I had what was diagnosed as an iron deficiency on the new growth of my Hygrophila Polysperma Sunset, which was growing with white veins. All I changed was I added additional DPTA Iron to my micro mix, and no more white veined growth was seen. I believe @Zeus. also had some quite significant iron issues on his tank if memory serves.
 

dw1305

Expert
Joined
7 Apr 2008
Messages
10,971
Location
nr Bath
Hi all,
Try not dosing it at all for several weeks, take weekly photos. It will take an age for iron deficiency to appear across the entire tank.........
I'd agree with @ceg4048 & @Geoffrey Rea on that. I've had long time periods (certainly months and possibly years) where I haven't added iron (FeEDTA) to the tanks, without the floating plants showing iron deficiency.

I add iron EDTA now on a <"slightly more regular basis now">, but purely because iron isn't mobile within the plant and after you have deficiency symptoms it takes a while for new leaves to grow (once iron becomes available again). Iron deficiency, in a floating plant, is the only deficiency I'm usually willing to diagnosis.

You have a <"myriad of possibilities"> where older leaves are chlorotic and growth is compromised, but small, very pale, new leaves are strongly indicative that iron is <"Liebig's limiting nutrient">.

My guess is that nutrient deficiencies are much more likely to occur with carbon (C), nitrogen (N), potassium (K), phosphorus (P), magnesium (Mg) etc. (and probably in that order), purely because the plants need more of them.
I had what was diagnosed as an iron deficiency on the new growth of my Hygrophila Polysperma Sunset, which was growing with white veins. All I changed was I added additional DPTA Iron to my micro mix, and no more white veined growth was seen. I believe @Zeus. also had some quite significant iron issues on his tank if memory serves.
We have a number of threads where plants show <"iron deficiency">, often involving <"Rotala rotundifolia">.
Turning the question on its head though Geoff, what is the reason not to dose daily?
If I had an automatic doser, and was interested in optimal plant growth, I probably would dose daily, rather than scattering a pinch of FeEDTA in the tank when I notice the vial in the drawer.

If you aren't interested in optimal plant growth then I'm pretty sure it doesn't matter when you dose. If you use the Duckweed Index then you may find you don't dose anything for extended time periods.

cheers Darrel
 
Last edited:

Geoffrey Rea

Global Moderator
Staff member
Joined
27 May 2017
Messages
988
Location
Cambridgeshire
Turning the question on its head though Geoff, what is the reason not to dose daily? What is the benefit of dosing alternate days instead

Couldn’t tell you, all paths seem to lead to Rome with EI and quite frankly I say try it, try as many different methods and report any discernible difference in your plants. Why is EI formatted with six days application with a seventh day of rest? What is this, Genesis?

but I had what was diagnosed as an iron deficiency on the new growth of my Hygrophila Polysperma Sunset, which was growing with white veins. All I changed was I added additional DPTA Iron to my micro mix, and no more white veined growth was seen.

Not to nit pick but that is plant specific, not tank wide. Different plant but... As Darrel has mentioned elsewhere with Rotala’s, they can be resistant to iron uptake due to adaptation from growing in specific habitat conditions.
 

Gulczi

Member
Joined
9 Aug 2020
Messages
29
Location
Poland
So I will make a EI fert with seperate bottles for Macro and Micro but I will dose daily Macro and Micros instead of 3x week.
Will see what happens..
 

lilirose

Member
Joined
13 Aug 2020
Messages
283
Location
Ireland
I don't dose EI, but when I add iron at the same time as my weekly all-in-one, the water turns an ugly blackish colour. A couple of times I've dosed ferts, iron, and tannin tea on the same day and had the water turn black. Not "blackwater" tannin stained black, but straight up solid black, so that I could not see the fish or the plants. Attaching a photo as proof- you can barely see the bright blue Betta who is literally next to the glass, and you can see the reflection of my hands, the rest of the water is solid black- you can't see the back of the tank at all. I did not add anything unusual or in a larger dose than recommended.

Again I don't dose EI, but I thought that what you see in my pic is the reason for not dosing iron with the others.
 

Attachments

  • 2020-07-26 20.08.35.jpg
    2020-07-26 20.08.35.jpg
    2.4 MB · Views: 29
Last edited:

Similar threads

Top