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Weekly, Daily Ferts, what's the difference?

BarryH

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The more I read about fertilisers, the more confused I become. Can anyone please advise what is the difference is dosing daily, as opposed to dosing the same, but larger amount weekly?

I was looking at different fertilisers advertised on websites and couldn't really understand why some are dosed daily, some (EI) dosed every other day, and yet more dosed on a weekly basis.

Any advice or help would be really appreciated.
 
You dose daily and alternate days as the potassium phosphate reacts with the chelated iron in the micro and precipitates out and becomes unavailable to the plants. Thus if you dumped the lot in once a week you would pretty soon be suffering from iron deficiency and to a lesser extent phosphate deficiency both leading to plants dying and associated algae blooms.

Only applys if using high lights and CO2.

If non CO2 and low light once a week dosing is fine.
 
Also, the iron chelates break down for several reasons: in the presence of light, pH/KH too high, etc.

Dosing weekly or daily is connected to tank's growth speed. High light tanks get daily doses because they are "running fast", while non-co2 low light tanks can have a small weekly dose because they just "strolling in the park"

Dosing daily makes sure the ferts are available, at the very least at the day they are dosed. But the big doses will force the owner to do constant water changes to eliminate all the excess of nutrients in the water. This basically the Estimative Index foundation: provide every fert and CO2 in abundance, so they are not limiting the growth, and define the tank growth speed by the amount of light. Too much light and ferts/co2 might not be enough...

There are other fertilisation systems, like PPS Pro, Diana Walstad, PMDD, but I really like EI. You should study them as well, it will give you a better understanding about it.

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Good thread Barry,

My knowledge/understanding is limited to say the least but following on from Ian's post about dosing alternate days and how there's a reaction between potassium phosphate and chelated iron can I ask why it doesn't happen when dosing PMDD style? Just to reinforce I'm not scientifically minded so will probably take me about a month to read and re read any real science answers. The reason I ask is I use Tom Barr's PMDD with PO4 method since dealing with cups and teaspoons for measuring doesn't sit well with me.
 
Thanks for the great replies everyone. Really appreciated. So, if I've got it right, the biggest difference in the use of fetilisers depends mainly of if you're Hi or Low Tech and the same with lighting?
 
So, if I've got it right, the biggest difference in the use of fetilisers depends mainly of if you're Hi or Low Tech and the same with lighting?
Correct. If low light, the plants will consume less CO2 (carbon), less nutrients and produce less organic waste. The presence of high levels of organic waste cause algae and is not appreciated by fish.

So with lower light levels you can dose fertiliser less often, rely on fish poo & old fish food as carbon and fertiliser source, as well doing less frequent water changes (to remove organics and unused fertiliser), as the organic waste has time to rot away/be filtered away naturally.

Also with low tech, things go wrong more slowly eg algae appearing over weeks rather than a couple of days (or less) in high tech.

My knowledge/understanding is limited to say the least but following on from Ian's post about dosing alternate days and how there's a reaction between potassium phosphate and chelated iron can I ask why it doesn't happen when dosing PMDD style?
It doesn't happen with original PMDD as there was no phosphate in the mix, therefore chelated (iron) and other chelates stayed chelated in the bottle and in the tank.

With PMDD modified with PO4, which you refer to, you must dose macros and micros on alternate days. It is the addition of potassium phosphate to PMDD formula that makes alternate dosing being required.
 
Thanks for the reply Ian. I'm starting to get there, slowly I admit but I am getting there. :)
 
The tricky one IME is Iron. This is the reason why we have so many chelators, with different properties. I think using a blend of chelators is a good thing. I tried gluconate and EDTA for a while, but my water is too hard for that, and now I am tending to EDTA/DTPA.

If you are a subscriber of BarrReport.com, I would suggest that you go through the reports about ferts (N, P, K and Fe).

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Thanks also for answers folks and patience (Barry H) as feel like I've hijacked your thread.

I'm a bit scared to ask/raise as more than likely I won't understand the answer, but the pmdd + po4 method taken from Tom Barr's site is actually daily dosing of both.

http://www.barrreport.com/forum/bar...more-accuracy-want-daily-pmdd-style-ei-dosing

Maybe it's just going from zero dosing to some is what I'm seeing but it seems to be working.

All the best
 
Great thread, without going off course - how does my 'all in one' co2 supermarket feet mix deliver ion?

Also, I dose flourish excel alongside this 'all in one' mix, am I wasting my time?
 
Just to make matters more confusing you can dose EI daily too :D. This is what i do anyway.

I also keep iron restricted to the substrate using clay and soils. This will provide a concentrated source of the essential trace or micro nutrients leaving me to focus on the macros.
 
how does my 'all in one' co2 supermarket feet mix deliver ion?
It keeps the iron chelated in the bottle by keeping the solution acidic, thus preventing it reacting with the phosphate. In the tank it will unchelate due to a lowering pH and light, but hopefully the phosphate will be diluted and the amount that reacts will be minimal.
 
Great thread, without going off course - how does my 'all in one' co2 supermarket feet mix deliver ion?

Also, I dose flourish excel alongside this 'all in one' mix, am I wasting my time?
Chelators will be preserved under the right conditions, most cases by keeping the solution out of light reach and stable/acidic (e.g. ascorbic acid, vinegar potassium sorbate, etc).

Using excel in a solution will preserve the solution further. Glutaraldehyde is a sterilisation chemical (e.g. Metricide). One point to consider though is that many manufacturers already confirmed that when Glutaraldehyde is either exposed to air for some time and/or diluted below 1%, it will eventually breakdown. Different concentrations will give different results, but studies have shown that the average life of dosed Glutaraldehyde is around 10h or less.

Most chelates are sold with information about its pH effective range, like EDTA (~pH 7), DTPA (~ pH 8) and EDDHA (~ pH 10). Other chelators have different characteristics: Iron Gluconate is a much weaker chelator that requires low pH and hardness, but allows plants to acquire Iron with much less effort; Fe-HEDTA is used under pH 7 in phosphate-rich water.

In many cases, these chelators will be broken by the pH shift in the tank, specifically a higher pH, as many people use the wrong chelate for their systems. I will not afirm that no interactions between phosphates and iron happens on a tank, but one must understand that the differences in concentration between a 500ml bottle and a 100l tank are quite big.

Nonetheless, dosing in alternate days is a good thing, if people keep it steady. The point is making the ferts available, and balanced against CO2 and light

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Using excel in a solution will preserve the solution further. Glutaraldehyde is a sterilisation chemical (e.g. Metricide). One point to consider though is that many manufacturers already confirmed that when Glutaraldehyde is either exposed to air for some time and/or diluted below 1%, it will eventually breakdown. Different concentrations will give different results, but studies have shown that the average life of dosed Glutaraldehyde is around 10h or less.
I think years ago, can't remember here or elsewhere, someone did experiments to make a ferts solution of macro salts, micros and acidifier and Excel or gluteraldehyde as an all one including liquid carbon fertilisation solution. I think they found that when the gluteraldehyde was diluted to give an acceptable dose with the macros/micros, it either reacted with something or decomposed. Not to sure any definitive conclusion was reached, other then better to dose liquid carbon separately from micros/macro.
 
I think dilution once the ferts are in the tank must be a big part in this?
Because even dosing macro and micro on seperate days there will still be iron and phosphate left from the previous days doses in the tank water.
If the binding still happens it would become iron phosphate making both nutrients unavailable to the plants?
 
I think dilution once the ferts are in the tank must be a big part in this?
Because even dosing macro and micro on seperate days there will still be iron and phosphate left from the previous days doses in the tank water.
If the binding still happens it would become iron phosphate making both nutrients unavailable to the plants?

I do not buy the talk about "all iron gets precipitated". And I dose 10ppm of PO4 weekly, so around 13 with accumulation. I know these cheap tests we use are not reliable, but if, after checking them against known solutions, I can still find traces of the 2 days old Fe, than it most definitely was still available.

Again, you gotta know your ferts, chelators, etc. At some point I will send my water to the lab, but that can wait.

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When you fertilize daily you keep a more stable dosis, with small spikes, so the amounts of nutrients are always the ones plants need but there're not leftovers for algae. If you dose weekly you produce a huge spike in the nutrients levels, but plants doesn't use more nutrients, in this case algae can proliferate.

This is another reason why daily dosage is so popular between advanced aquascapers. But all the chemistry related reasons said before are correct too.

I fertilize on a daily basis, with good results.




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When you fertilize daily you keep a more stable dosis, with small spikes, so the amounts of nutrients are always the ones plants need but there're not leftovers for algae. If you dose weekly you produce a huge spike in the nutrients levels, but plants doesn't use more nutrients, in this case algae can proliferate.

This is another reason why daily dosage is so popular between advanced aquascapers. But all the chemistry related reasons said before are correct too.

I fertilize on a daily basis, with good results.




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Two things got my attention:

First, plants do have an optimal range for nutrients. So underdosing or overdosing ***outside of this range*** is not a good thing. But this range is quite wide. I mean, IME, 10 to 100ppm of nitrates for plants is fair game. Also, by the end of the week, with accumulation, the fert concentration is quite high. 10ppm + of PO4.

Second, I have never seen excess nutrients (except ammonia) cause algae. Excess organics, ammonia do cause issues.

And to make it clear, plants and algae do not compete for nutrients. Light is a much better candidate. But algae can handle much worse scenarios than plants.

What remains a constant observation is that when plants thrive, algae does not ;)

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