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Front loading vs daily dosing

hypnogogia

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Over in the IFC fertiliser thread (and excellent tool btw.) I asked a question about front loading and accumulation, which I thought was worthy of further discussion/exploration.

My question was why, with front loading, one only doses for the replacement water and not the whole tank. The answer to that was to avoid accumulation. Now, if I understand correctly, with daily EI dosing, we do regular 50% water changes to keep accumulation in check. My question though would be, why would we be more concerned with accumulation when front loading than when daily dosing? The accumulation that occurs would conceivably be the same amount irrespective of approach. So, the question still remains - we could dose for the whole tank and front load, do a 50% water change to keep it in check, or if we are genuinely concerned with accumulation, then perhaps we should only does for the weekly water change amount even if dosing on a daily basis.

I'd be interested in others' views and also if I've got completely the wrong end of the stick.
 

tiger15

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I think the daily dosing is not about accumulation, but to provide steady supply of nutrients plants prefer. The weekly 50% WC is to reset and prevent accumulation.

I don’t dose daily except iron which has short bio available life. I front load all other nutrients after weekly 75% WC. I keep heavy bio load that supplement substantial N and P daily.
 

GreggZ

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Over in the IFC fertiliser thread (and excellent tool btw.) I asked a question about front loading and accumulation, which I thought was worthy of further discussion/exploration.

My question was why, with front loading, one only doses for the replacement water and not the whole tank. The answer to that was to avoid accumulation. Now, if I understand correctly, with daily EI dosing, we do regular 50% water changes to keep accumulation in check. My question though would be, why would we be more concerned with accumulation when front loading than when daily dosing? The accumulation that occurs would conceivably be the same amount irrespective of approach. So, the question still remains - we could dose for the whole tank and front load, do a 50% water change to keep it in check, or if we are genuinely concerned with accumulation, then perhaps we should only does for the weekly water change amount even if dosing on a daily basis.

I'd be interested in others' views and also if I've got completely the wrong end of the stick.
Front end loading and dosing for replacement water and not the whole tank are two entirely different topics.

Contrary to what most believe people like me who front end load do it to keep nutrient levels more stable. Dosing every other day typical leads to a very low nutrient level right after a water change, and then the levels rise and peak right before the next water change.

I can use my tank as an example. My plant uptake of nutrients is just a little higher than the tank generated nutrients (fish/feeding/waste). Let's say I were to dose 12 ppm NO3 weekly and perform a 2/3 water change. If I were to dose the traditional way I would perform a water change then dose macros every other day. This is what my nutrient levels in the tank would look like. Pay attention to the daily NO3 level in week 11. Notice how the nutrient levels would start very low then rise until the end of the week. Many sensitive species hate that dip in nutrients.
12 ppm EI.jpg


Now let's take the same dosing but dose all weekly macros right after a water change. Notice the difference in the daily NO3 level in week 11.
12 NO3 front load.jpg


I think you would be surprised at how many people are now using this method. Personally I started front end loading about 5 years ago or so. My main thought was that if there is an "optimum" amount of nutrients in the water column that plants prefer, then why not try to keep it there?

If anything else it sure is a lot more convenient. And even if someone does not front end load, most would benefit from dosing something like 50% of the weekly total right after a water change then two 25% doses during the week. You want to avoid that big drop of nutrients from the water change.

Now as to dosing based on the amount of water removed or the entire tank it is simply a matter of semantics. It's two ways to report the same thing. I started a crusade years ago to get people to think of "target" dosing, but old habits die hard.

The reason I think it works better is that a lot of times people try to copy someone else's dosing. But what they don't realize is that if they are not on the same water change schedule, then they are not providing the same level of nutrients in the water column. It all has to do with accumulation.

If you change less water, then your accumulation will be higher. If you change more water then your accumulation will be lower. By a lot.

There is simple formula to calculate the theoretical maximum accumulation of fertilizers. It's the weekly ppm divided by the water change percentage.

So let's take NO3. If someone is dosing 12 ppm weekly, this is how water change percentage affects accumulation.

12 ppm weekly at 25% water change is 12 ppm/0.25 = is 40 ppm max NO3 accumulation.
12 ppm weekly at 50% water change is 12 ppm/0.50 = is 24 ppm max NO3 accumulation.
12 ppm weekly at 75% water change is 12 ppm/0.75 = is 16 ppm max NO3 accumulation.

So you see 12 ppm NO3 dosing can mean a lot of things depending on the water change schedule.

If our "target" in the water column is 24 ppm, then we would report it as a 24 ppm target dose. It is exactly the same as dosing 12 ppm NO3 with 50% water change. So again it's two ways of saying exactly the same thing.

I hope that makes some sense but I am guessing you are sorry that you asked. Now I need to lie down with a cold compress on my forehead for a few minutes!:D
 
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Hanuman

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My question was why, with front loading, one only doses for the replacement water and not the whole tank. The answer to that was to avoid accumulation.
That is not exactly how I put it in the IFC calculator thread. What I said, or at least wanted to convey, is that the by-product of using your WC volume as a basis to dose is no fert accumulation, but that is NOT the aim/objective of front loading. Gregg explained it above which is consistent with the explanation I gave <here>.
Here is also a <thread> where we discussed about it. And here <a specific post> in that thread where I made a 1 week simulation to compare front load vs other dosing technics.
 
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hypnogogia

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@GreggZ thank you that is very helpful, by means of the tables you presented. I have just one further question.

12 ppm weekly at 25% water change is 20 ppm/0.25 = is 40 ppm max NO3 accumulation.
12 ppm weekly at 50% water change is 20 ppm/0.50 = is 24 ppm max NO3 accumulation.
12 ppm weekly at 75% water change is 20 ppm/0.75 = is 16 ppm max NO3 accumulation.
If it is 12pm, why is the calculation 20er/0.25? What would it be if it is 15ppm weekly?
 

Hanuman

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If it is 12pm, why is the calculation 20er/0.25?
It looks like @GreggZ got a bit excited and finger happy. It should read:

12 ppm weekly at 25% water change is 12 ppm/0.25 = is 48 ppm max NO3 accumulation.
12 ppm weekly at 50% water change is 12 ppm/0.50 = is 24 ppm max NO3 accumulation.
12 ppm weekly at 75% water change is 12 ppm/0.75 = is 16 ppm max NO3 accumulation.

What would it be if it is 15ppm weekly?
15 ppm weekly at 25% water change is 15 ppm/0.25 = is 60 ppm max NO3 accumulation.
15 ppm weekly at 50% water change is 15 ppm/0.50 = is 30 ppm max NO3 accumulation.
15 ppm weekly at 75% water change is 15 ppm/0.75 = is 20 ppm max NO3 accumulation.

There is a calculator done by Zorfox that calculates accumulation. Rotala Butterfly also has an accumulation calculator.
 

ian_m

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Of course front loading macros precludes any dosing of micros as micros, especially the iron, will react with the phosphate in the macro and precipitate out of solution and become unavailable to the plants. Also the chelates in the micro generally have a short (24 hours ?) lifetime once in the tank, due plants scoffing, the chelates breaking down in alkaline conditions and presence of bright light.

This is why EI doses alternate days so the micro does not have a chance to react with the macro phosphate.

I have certainly seen here, peeps with iron deficiencies (in their tank), due to bulk once a week dosing macro and micro and eventually plants suffer iron deficiency of pale yellow/green new growth. Takes a while, maybe a year until all the "other iron" in the tank is exhausted, but was easily fixed by dosing EI properly, on alternate days. I don't think the existing plants recovered too well, as iron is not too mobile in the plants, but all new growth was not iron deficient.
 

GreggZ

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It looks like @GreggZ got a bit excited and finger happy. It should read:

12 ppm weekly at 25% water change is 12 ppm/0.25 = is 48 ppm max NO3 accumulation.
12 ppm weekly at 50% water change is 12 ppm/0.50 = is 24 ppm max NO3 accumulation.
12 ppm weekly at 75% water change is 12 ppm/0.75 = is 16 ppm max NO3 accumulation.


15 ppm weekly at 25% water change is 15 ppm/0.25 = is 60 ppm max NO3 accumulation.
15 ppm weekly at 50% water change is 15 ppm/0.50 = is 30 ppm max NO3 accumulation.
15 ppm weekly at 75% water change is 15 ppm/0.75 = is 20 ppm max NO3 accumulation.

There is a calculator done by Zorfox that calculates accumulation. Rotala Butterfly also has an accumulation calculator.
Thanks @Hanuman yes I pulled the trigger too fast and didn't read my own post close enough. Thanks for clarifying.
 

GreggZ

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This is why EI doses alternate days so the micro does not have a chance to react with the macro phosphate.
This idea of iron precipitating at the levels we dose has been disproven many times over. Many, many people like myself front load macros and daily dose micros, as do many of the best tanks in the world. Barr himself has endorsed this method. And every all-in-one fertilizer like APT complete has PO4 and iron in the same bottle.
 
Last edited:

John q

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This is why EI doses alternate days so the micro does not have a chance to react with the macro phosphate.

Many, many people like myself front load macros and daily dose micros, as do many of the best tanks in the world.

Just to play devils advocate: ~

I wonder if Front loading works better in soft water/ low ph tanks where the precipitation issues are less of a concern?

@GreggZ I took the liberty of editing macros/micros. 😀
 

tiger15

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I am surprised to learn that daily dosing without front loading can lead to nutrient dip after WC . This is the opposite effect of EI intent to maintain stable nutrient levels. But I guess it is situation dependent as the dynamic of each set up is different depending on one's WC schedule and volume, high light stems versus low light epiphytes, heavy life stock versus light, and variability of source water. The only way to figure out what's going on is to test daily as Gregg did. Gregg runs a high light Dutch system with heavy life stock, and his source water is purified DI, so it is not an average set up.

I front load macros and micros after WC, and supplement with chelated Iron every other day. I have very heavy life stock of cichlid, and change 75% water with tap weekly. My testing showed that N and P are about same pre and post WC after dosing. I don't have test kits for K and iron, but my assumption is that K is enough but iron is bio unavailable and therefore I need to dose iron frequently.
 

dw1305

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Hi all,
This idea of iron precipitating at the levels we dose has been disproven many times over.
I'm not convinced, mainly because it is the mechanism that <"phosphate stripping"> uses at wastewater plants.

Are you saying that the phosphate (PO4---) level is to low to precipitate out the iron (Fe+++) ions? or that the HCO3- and OH- ions will mop any ferric iron (Fe+++) ions before the PO4--- ions do?

Anecdotally we have also have a lot of threads where people (with <"traditional apologies"> to @jameson_uk ) have dosed iron (Fe+++) and still have <"iron deficiency symptoms">, presumably as a result of using a chelator that isn't suitable for <"their water hardness">.

cheers Darrel
 

GreggZ

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Hi all,

I'm not convinced, mainly because it is the mechanism that <"phosphate stripping"> uses at wastewater plants.

Are you saying that the phosphate (PO4---) level is to low to precipitate out the iron (Fe+++) ions? or that the HCO3- and OH- ions will mop any ferric iron (Fe+++) ions before the PO4--- ions do?

Anecdotally we have also have a lot of threads where people (with <"traditional apologies"> to @jameson_uk ) have dosed iron (Fe+++) and still have <"iron deficiency symptoms">, presumably as a result of using a chelator that isn't suitable for <"their water hardness">.

cheers Darrel
Darrel I will have to dig up some of my conversations with Barr on this topic. I have them but not at my fingertips. It has to do with the very small relative amounts that we use. Like I said I know many of the best in the hobby who routinely dose macro/micros together and have no issue with iron. It's just not something that successful people I know worry at all about.

And yes you make a very good valid point that using a source of Fe that is not suitable for the pH of the tank could lead to an iron deficiency. As I am sure you know, EDTA is the source of iron in many commercial micros mixes. It will be most effective at pH less than 6.5. Tanks with higher pH should be using DTPA.

As to "iron deficiency symptoms" that is a topic for debate. Many deficiencies look very much alike. Saying you "see" an iron deficiency and actually having one can be two different things. I have found more often than not when someone claims they see one it can be traced to something completely different.

Best way to diagnose is to adjust iron dosing (and ONLY iron dosing) and observe.
 

GreggZ

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I am surprised to learn that daily dosing without front loading can lead to nutrient dip after WC .
The principle is really very simple. Let's say you have 40 ppm NO3 in the water column. Remove 50% of the water and replace and you now have 20 ppm NO3 in the water column. Then you dose daily or every other day and the levels slowly rise until the next water change.

But yes as you said much depends on the individual tank. The types of plants, the plant mass, light, CO2, fish load, maintenance habits, etc all play a role. In general I have found keeping levels stables is better in the long run, especially with many harder to grow stems.

For a tank with with little fish load, even a decently large dose right after a water change can bring the levels back up. Takes some tinkering and a little math to figure out what works best for each tank. If anyone wants the spreadsheet that I posted above PM me and I will send it to you.
 

tiger15

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But the math only tells you the input, not the uptake which varies with plant mass, plant health, type of plants, light intensity, CO2 and other variables. You have super high light, high CO2 injection rate, healthy and hungry stems, so the uptake is on fast lane. Math can only tell you so much. Ultimately, actual measurements count most. Unfortunately, there are no good home testing kits for K, bio available iron, and most micros, so mathematical guessing is the only means.
 

dw1305

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Hi all,
As to "iron deficiency symptoms" that is a topic for debate. Many deficiencies look very much alike. Saying you "see" an iron deficiency and actually having one can be two different things. I have found more often than not when someone claims they see one it can be traced to something completely different.
Yes I'd agree, there are a lot of deficiencies which <"are difficult to diagnose">, but I think iron (Fe) is possible, mainly because there aren't many nutrients that are <"non-mobile and cause chlorosis in new leaves">. You also have probability on your side, due to the difficulties of keep iron ions in solution.

This is classic <"iron deficiency">.

dad12186cb152cccee11028dc11c34f4-jpg.135357


cheers Darrel
 

ElleDee

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There is simple formula to calculate the theoretical maximum accumulation of fertilizers. It's the weekly ppm divided by the water change percentage.
I may be in my thirties with an MS, but I didn't understand why inverse numbers were useful until I figured all this out.

I also didn't really get what you meant by target dosing until I started ignoring accumulation altogether and realized I could just do my calculations based on the amount of water I remove. It doesn't matter how big the tank is or what percentage you are changing, you just dose the amount of water you take out to the target. (Obviously there are still the unknowns in play (actual plant uptake and nutrients from fish waste/soil/etc.) that benefit from large WC to keep you at your baseline, but that doesn't affect the calculations.)
 
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