CaMg(CO3) aka Dolomite for remineralization?

[MichaelJ]

Hi @X3NiTH I did a WC on Friday using the Ca and Mg Gluconate compounds as remineralizers instead of CaSO4 / MgSO4. I decided to only use it in one of my tanks first - just to error on the safe side in case I would notice any unanticipated side effects. Immediately I noticed that the water was a slightly cloudier than I normally experience, somewhat excepted and it all cleared up pretty quickly, so no problem there.
I waited a couple of hours before I added the traces (which is mostly Iron 0.28 ppm to be somewhat exact. I dose traces twice per week). A few hours later, after adding the traces, the tank looked like someone had poured a gallon of whole milk into the tank 😉 However, by Monday morning the tank had mostly cleared up and everything seems fine.

Now, given the reaction in the first tank, I decided to postpone the WC in my second tank until Monday (actually, until the first tank had cleared up) and skip the KH2PO4 dosing (just to somewhat rule out the Iron <-> Phosphate reaction) and wait a full 24 hours before adding the traces. This morning (Tuesday) still no negative reaction and the water was crystal clear and then I went ahead and added traces and ... boom! ... A few hours later the tank was as cloudy as the first tank was after adding the traces. I have no doubt the tank will clear up over the next 48 hours, so I am not panicking - I got plenty of fine Bourbon around to self-medicate in case that happens 😄 ...

Of course, I can't totally rule out the Phosphate <-> Iron reaction because my phosphate levels are intentionally pretty high in both tanks, but I haven't seen this reaction for a very long time (not since using high doses of Seachem Iron... and that wasn't even this bad) and never after switching over to DIY dosing, and I haven't changed my trace mix or KH2PO4 dosing... In fact, I am still using the same trace bottle I mixed a couple of months ago, and I always shake the bottle well before dosing.

With the first tank, I thought that it perhaps could be a bacteria bloom (caused by the Gluconate?) , but I would rule that out as well as the reaction obviously seems to coincide with adding the traces in both cases - and at very different time intervals.

TDS checks and checked out as excepted, both in the tanks and in the WC water prep buckets, so I am pretty certain that this is not due to getting the dosing of the Gluconate compounds or any other compound wrong.

So, my guess is that it might be something with the traces (Iron) reacting with the Ca Gluconate and/or Mg Gluconate that is causing the water to go milky?

Also, I am wondering if having the tanks clearing up means all is good - i.e. will the dosed Iron be available for the plants by then?

One solution is that I might have to split my trace dosing up in say 6 doses throughout the week instead of two large doses in order to avoid this reaction - if that makes any sense? That is probably going to be my next experiment. It will probably still happen to some extent, but with 1/3 the dose it might not be an issue.

Again, I am not too worried as I am confident the second tank will clear up over the next 48 hours, just like the first tank did - and livestock appears to be doing fine in both tanks! ... although the fish might be wondering why I am clowning around with chemicals 🙂

Cheers,
Michael

 

[X3NiTH]

Interesting!

If the fogging of the water develops over a couple of hours and not an instantaneous precipitation reaction on first addition then it could be traces accelerating a bacterial bloom feeding on the Gluconate.

I’m not going to discount precipitation reactions or iron jumping chelates then precipitating, you would have to test for the presence of Iron and Phosphate pre and post addition to see if there was a change in amounts.

You can null test for biological reactions by using a sterile environment using the same water chemistry as in the tank but hasn’t seen any biological processes, dose the additives and check for reactions, if there is a reaction then it’s a chemical process.

It might be worth getting hold of test kits for both Iron and Phosphate so you can monitor any rate of change.

I’m gonna order up some Calcium and Magnesium Gluconate and perform some standalone tests to compare.

🙂

 

[MichaelJ]

Interesting!

If the fogging of the water develops over a couple of hours and not an instantaneous precipitation reaction on first addition then it could be traces accelerating a bacterial bloom feeding on the Gluconate.

Hi @X3NiTH Interesting. I did find a tiny reference to bacterial bloom on Reef central - Apparently Calcium Gluconate compounds are commonly used among reefers - such as Seachem Reef Calcium

Also I was speculating that the Gluconate, with all its Carbon and Hydrogen atoms is essentially a lot of carbohydrates, would essentially be bacteria food causing the bloom - on the other hand the carbohydrates could also be beneficial for plants(?). I suppose if it is a bacterial bloom it wouldn't be a good thing as it could potentially bring oxygen to critical low levels especially overnight and cause waste build up when the bacteria dies off.

I’m not going to discount precipitation reactions or iron jumping chelates then precipitating, you would have to test for the presence of Iron and Phosphate pre and post addition to see if there was a change in amounts.

You can null test for biological reactions by using a sterile environment using the same water chemistry as in the tank but hasn’t seen any biological processes, dose the additives and check for reactions, if there is a reaction then it’s a chemical process.

I see - you mean such as adding the traces (in relative proportions) to my WC prep bucket and see if it clouds up?... thats a good idea!

It might be worth getting hold of test kits for both Iron and Phosphate so you can monitor any rate of change.

I was wondering about this myself. I don't have an Iron test kit, but ordered this from Seachem last night.

I’m gonna order up some Calcium and Magnesium Gluconate and perform some standalone tests to compare.

That would be awesome - Would be great to have a 2nd take on this and a chemists assessment of the situation.

Well, I am going to do another WC in my first tank Friday and 2nd tank Saturday and then spread out the trace dosing over the week to see if that changes the situation. If not, I will probably change back to the CaSO4 or find some compromise dosing between the Ca Gluconate and CaSo4 and keep the Mg Gluconate - So there are plenty of things to try... I hope it works out though.

Cheers,
Michael

 

[MichaelJ]

Hi @X3NiTH , I did the null test as you suggested:

Test 1. Added only Ca Gluconate (6.5 grams to reach 32 ppm of Ca) to a 5 US gallon bucket of tap water (my tap is "0" GH as it goes through a KCl resin softener as mentioned)... I had it sitting for about an hour to let the Ca Gluconate dissolve completely (i.e. stirring it once in a while until I couldn't see any residue at the bottom). After that I added 1/8th the amount of trace I would add to my 40 Gallon tanks, and let it sit for a couple of hours. No cloudy or milky reaction at all.

Test 2. Filled a 2nd bucket with tap water and this time I added ALL the compounds I added to my last WC water (Ca and Mg Gluconate’s, KH2PO4, Mg(NO3), MgSO4 and Prime ) I had it sitting for an hour to let everything dissolve. After that I added the trace, and let it sit for a couple of hours. Still no reaction at all.

Of course, this test is still rather inconclusive as the chemical markup in my tanks is obviously somewhat different - including pH, temperature etc. And I didn’t mix in RO water with the tap water as I usually do. So this test comes with a number of uncertainties except for the bacterial load which is probably very near zero in my tap water compared to the tanks.

I am starting to lean strongly towards the reaction being a biological reaction (a bacterial bloom of sorts) rather than a chemical reaction. It’s just really strange (to me at least) that it had to coincide with adding the trace in both instances, but there must be a trigger there I guess.

I still have the two buckets sitting just to see how it might evolve by tomorrow morning - as of now (writing this post) its already been sitting there for 6 hours and still no adverse reaction in either of the buckets.

Well, the good news is that my 2nd tank is almost cleared up by now and livestock in both tanks still appears to be fine.

Cheers,
Michael

 

[X3NiTH]

Good job on the null test!

You could run the external positive null test for completeness with water drawn from the tank at water change and redosing Gluconate up to 64ppm Calcium and add more trace to feed any bacteria in the water column to gain a positive result of blooming, bloom strength if detectable will be much less than if the water has gone through the filter a few times because that’s where the excess growth in the water column will mainly come from. It’s not entirely necessary to run this test as you already have a positive result in the tank but if its one more itch to scratch then scratch it!

If you want to inhibit the bloom effect (for oxygen safety) you could run UV on the filter outlet.

Btw totally not a chemist, potions book maybe!

🙂

 

[MichaelJ]

Good job on the null test!

Hi @X3NiTH Thank you. I had the buckets sitting over night as mentioned. One bucket I left with the lit off (Test 1 with only the Ca Gluconate) and the other I put the lit on (Test 2 - with all the compounds). In the afternoon (Thursday - about 24 hours after doing the test) I could definitely tell that bucket 1 was getting really cloudy while bucket 2 was still clear (it had the lit on..). In the night both were pretty much equally clouded up. With some scummy gunk on the surface that almost feel like soap... Now, I do not know if the same thing would happen if I would just leave a bucket of tap water sitting for 24-36 hours. I am running that test at the moment - I don't except it to cloud up or build up similar scummy gunk... but let's see.

I think the evidence is strongly in favor of a bacterial bloom. And it also made me think that back in the day when I was (over)dosing Seachem Iron (which is Fe Gluconate as it turns out), I might have experienced a bloom rather than the aforementioned Fe <-> Phosphate reaction. Pure speculation of course.

I am going to do my WC's and maintenance today and use a mix of Ca Gluconate and CaSO4 instead of the full 6.5g of Ca Gluconate only, as I did before.

On a positive note, when I did the regular 2nd weekly trace dosing in the tanks on Thursday (a day later than usual) I did not get a negative reaction and both tanks are remaining crystal clear. Water parameters for both tanks (KH,GH,pH,TDS) are all in line with expected values. I received the Iron test kit, so I will check for that as well and see what indicative measure I get - don't know what level of reliability I am supposed to expect.

You could run the external positive null test for completeness with water drawn from the tank at water change and redosing Gluconate up to 64ppm Calcium and add more trace to feed any bacteria in the water column to gain a positive result of blooming, bloom strength if detectable will be much less than if the water has gone through the filter a few times because that’s where the excess growth in the water column will mainly come from. It’s not entirely necessary to run this test as you already have a positive result in the tank but if its one more itch to scratch then scratch it!

Good idea - I will try that too.

If you want to inhibit the bloom effect (for oxygen safety) you could run UV on the filter outlet.

Yes, I do actually have UV filters (two 9W Green Killing Machine) - They are not in the tanks at the moment. I took them out quite a while ago, but they might be worthwhile to put in if I experience a strong bloom again.

Btw totally not a chemist, potions book maybe!

Thats close enough 🙂

Cheers,
Michael

 

[MichaelJ]

Hi @X3NiTH Just a quick update on the Gluconate experiment. I did my WCs, but left out the Ca Gluconate, but still went with the small dose of Mg Gluconate. Now, after reading a tangential post by @ceg4048 I am starting to think the Gluconate might be a bad idea... I am referring to this post - specifically the comments on carbohydrates. Well, I was kind of alluring to that idea when I originally said my fish and plants would be bathing in sugar water, but I obviously didn't understand the implications 🙂 ... if these reactions are in fact correlated.

Also, the bucket I left overnight with just tap water (lit off, same conditions) didn't develop any cloudiness, so no surprise there.

I haven't dosed traces after the WCs yet but will update the thread when that happens.

Cheers,
Michael

 

[MichaelJ]

Added the Traces (mostly Iron) to my tanks today - no reaction that I can tell... Of course, there might still be a bloom, but its not enough for me to perceive visually. So for now, I think I am just going to go with the Mg Gluconate for my partly Mg dosing (I also use Mg(NO3) for N and Mg), skip the Ca Gluconate altogether and just use CaSO4 for my Ca dosing. Wish I could avoid the 26 ppm of Sulphate with the CaSO4, but still better than the CaCl that gave me 58 ppm of Cl for the same ppm (32) of Calcium. Well, was well worth trying. I still would like a somewhat better understanding of the interactions.

Cheers,
Michael

 

[MichaelJ]

The answer below was posted in an unrelated thread Just thought I would add this here as it was a Q/A related to this discussion about the Gluconate compounds:

ceg4048 said:
I've looked at that thread and it seems like a good possibility that the cloudiness may be due to bacterial reaction. I don't know exactly which tank bacteria can directly metabolize gluconate as opposed to glucose. There is a difference in the metabolic pathways when comparing the two.
It could be innocuous but generally I'm not really a fan of supporting large bacterial colonies simply because they typically are aerobic and so take oxygen away from the fish and plants.
Also, I'm not really sure what the residue of this gluconate metabolism would be. Whatever it is, it should be gotten rid of, and this might suggest an endless water change loop (maybe). So if you are doing all this for shrimp there could be a downside. I might have missed it somewhere along the way and you may have rejected it for some reason, but CaCl is a great way to increase Ca without increasing the KH, and Mg, well, you don't really need much of this stuff for plants at all (maybe for shrimp again?). Mg just has to be non-zero, so a little bit of Epsom Salts is all you need from a plant perspective.
Plants accrue the micronutrients within the leaves and these metals never move from the leaf, so if the dosing is regular next week the leaves will have more of everything than they do this week. I'm also not sure what the aversion is to high SO4 either, unless it's another shrimp thing. It could be that you're overthinking the scheme. Unless the shrimp species is something out of the ordinary I don't think it's necessary to optimize the water's content to this level of precision.

Yes, this was all mostly a shrimp and shrimplet thing, by trying to get rid of the additional Chlorides and Sulphates that the tanks won't really benefit from anyway, as far as I understand. With CaCl I couldn't really get my TDS down to the level I was aiming at while retaining the ~7 GH and NPK dosing, that is why I switched over to CaSO4, which shaved off quite a bit of the TDS and that actually has worked out just fine - by switching from CaCl to CaSo4 I essentially traded the 57 ppm of chloride with 26 ppm of sulphate, while keeping the same amount (32 ppm) of Ca.
I randomly discovered the Ca Gluconate and asked around if that would be an option. No one around here seem to have tried it and I couldn't find good references elsewhere of anyone using Gluconate based compounds in freshwater tanks - except for Gluconate combined with Fe (which supposedly improves the availability / plant uptake of the Iron?) and I was further speculating (yes, overthinking I guess...) that the carbon content of the Gluconate could be beneficial for the plants as well (?), so I thought it would be worthwhile to take a shot at using Ca Gluconate (and a small amount of Mg Gluconate). I didn't work out the way I had hoped. The bloom/cloudiness was obviously not pleasant to deal with, not to mention the fear of jepodizing the livestock and plants due to oxygen depletion if the cloudiness was indeed caused by a bacterial reaction. So I am back on CaSO4 and will stick to that. My remineralization scheme is actually very simple - 4 compounds mixed with my weekly Tap/RO water gives my tanks all the Ca,Mg and NPK that they need.

Thanks a bunch for taking a look at this.

Cheers,
Michael

 

[X3NiTH]

Where to begin ?

Okay I had a deeper delve into quite a few disparate papers (unfortunately as per usual I didn’t save the links) what could be happening with regard to the use of Gluconated compounds and chemical stability in the presence or absence of bacteria and water chemistry. One of the papers specifically discussed longevity in solution comparing the chelates of Gluconate, EDTA and Nitrilotriacetic acid.

What I found as a likely cause in this situation is that the bacteria mainly responsible for the bloom is likely Anaerobic in nature and the chemical process that we see with the bloom is conversion of Sulphates into Sulphides, the Sulphide of Magnesium (a paper discussed Magnesium Sulphate as having a high affinity for this process) is an Opaque White crystal, this Magnesium Sulphide will decompose over time in water to Hydrogen Sulphide, and Magnesium Hydroxide which will both further decompose. This process is already happening in any anaerobic areas within the substrate of the tank and that the Gluconate and added traces has fuelled its activity and increased its presence or reaction ability enough that conversion of sulphate to sulphide is visible within the water column, the activity of this bacteria doesn’t consume oxygen as it is toxic to it so any free anaerobes in the water column should be short lived providing the environment is well oxygenated and thus an oxidising environment.

The paper on the Chelates Gluconate, EDTA and NTA showed stored degradation was only a problem for long term viability in the presence of anaerobes when the solution was sulfonated. The degradation of Gluconate was well on the way to complete within 100 hours of dosing when anaerobes and sulphates were present in the solution.

Anecdotaly Bee Shrimp Mineral GH+ for remineralisation of water for Crystal shrimp contains only the Chlorides of Calcium and Magnesium, whether this is a deliberate choice to use these compounds to reduce anaerobic activity and hydrogen sulphide production in the substrate where gasses can form pockets and concentrate only to be released when disturbed by the activity of something digging is anyone’s guess, price usually drives everything but not always and sometimes the minutia of how things work is too much info for some folks who tune out thinking it’s just marketing talk.

Regarding remineralisation your not stuck with Sulphates if you want to reduce their content. You can increase the complexity of the water makeup by blending different compounds together to reduce there being one overriding side compound.

If we want to replicate nature then we need to provide mineralisation from all sources from the demineralisation of geology entering an ecosystem through to the biological process that act on this available chemistry which itself will return to chemistry when biological processes end, ad infinitum, as long as something further up the system is dying then other processes downstream will take advantage whether positive or negative.

A little bit of this and a little bit of that gets you to your ideal values whatever they may be. Which substances to choose from to form the blend would be at the easiest as single compound mixes or multi compound. Some compounds will have direct effects immediately upon addition that may shift the alkalinity or acidity of a solution thus its pH, some compounds will have effects that cause precipitation whether immediately or long term through biological or chemical processes and as you have discovered the Gluconate compounds can have unforeseen effects through it’s interaction with biological systems.

The simplest and most easily available compounds for hardness remineralisation are the Carbonates, Sulphates and Chlorides some are more soluble than others.

Here is the Extended Stallard Terniary diagram showing the majority of the worlds rivers and where they plot with regards to TDS rise and chemical makeup.

https://www.ukaps.org/forum/attachments/b328bd67-c009-419e-875d-e050e545d656-jpeg.148392/

The scheme doesn’t take into account organic derived mineralisation it’s primarily action through geology but does show plots for polluted rivers which likely arises through anthropogenic activity.

As demonstrated we’ve seen deriving the majority of mineralisation through a compound like Gluconate that has a high affinity for biological action may not be immediately problematical for biology but it may swing the balance in favour of one specific activity that may or may not have negative outcomes with possible potential harmful consequences ie a bacterial bloom derived either through aerobic bacterial action scavenging excess oxygen to the detriment of higher life forms or anaerobic bacterial action that breaks down polluting compounds that may produce short lived toxic intermediary products (ie Hydrogen Sulphide) at too high a value.

Focusing attention on Calcium compounds and aiming to reduce Carbonate, Sulphate and Chloride these can be reduced by supplementing with other compounds, the Gluconate we have discovered has clouding issues through a bacterial process (? Only in the presence of Sulphates and anaerobes). Calcium Hydroxide can be used but because of its ability to strongly moderate pH then it needs to be neutralised with an acid, if the acid comes as a more complex compound with Calcium then it can boost desired calcium levels also, this could be Calcium Citrate. Calcium Acetate can moderate pH also being a base but it has an equilibrium reaction in aqueous solution forming Acetic acid thus neutralising the pH moderation to a degree. More Calcium acid can be found in Calcium Tannate which is a chelated form of Calcium. If we look further to chelated compounds Calcium we would have to include EDTA, DTPA, etc. All ways to add available Calcium and this is not limited to Calcium supplementation you can fit this to any other element as long as they are soluble at the pressures, temperatures and pH we see in a typical body of aquarium water.

Too much of one thing maybe bad but careful alternate supplementation may reduce its overall effect.

🙂

 

[MichaelJ]

@X3NiTH Thank you for a very comprehensive answer and doing the research. There is a bunch of info here to digest - and while a lot of it is beyond my rudimentary knowledge of chemistry, I do think I get the gist of it. I will follow up with some additional questions and comments when I get a bit more time to digest it.

Cheers,
Michael

 

[MichaelJ]

Where to begin ?

Okay I had a deeper delve into quite a few disparate papers (unfortunately as per usual I didn’t save the links) what could be happening with regard to the use of Gluconated compounds and chemical stability in the presence or absence of bacteria and water chemistry. One of the papers specifically discussed longevity in solution comparing the chelates of Gluconate, EDTA and Nitrilotriacetic acid.

What I found as a likely cause in this situation is that the bacteria mainly responsible for the bloom is likely Anaerobic in nature and the chemical process that we see with the bloom is conversion of Sulphates into Sulphides, the Sulphide of Magnesium (a paper discussed Magnesium Sulphate as having a high affinity for this process) is an Opaque White crystal, this Magnesium Sulphide will decompose over time in water to Hydrogen Sulphide, and Magnesium Hydroxide which will both further decompose. This process is already happening in any anaerobic areas within the substrate of the tank and that the Gluconate and added traces has fuelled its activity and increased its presence or reaction ability enough that conversion of sulphate to sulphide is visible within the water column, the activity of this bacteria doesn’t consume oxygen as it is toxic to it so any free anaerobes in the water column should be short lived providing the environment is well oxygenated and thus an oxidising environment.

Does this essentially mean that if my tanks would not have had a high sulphate content (which they did, because I was using CaSO4 and MgSO4 for quite a while before trying out the Ca and Mg Gluconate) I wouldn't have gotten the Anaerobic reaction or bloom (assuming that is what it was) ? If so, the bloom could just be a short term reaction that would disappear after a couple of consecutive weekly water changes as the sulphate content gets lower?

The simplest and most easily available compounds for hardness remineralisation are the Carbonates, Sulphates and Chlorides some are more soluble than others.

Here is the Extended Stallard Terniary diagram showing the majority of the worlds rivers and where they plot with regards to TDS rise and chemical makeup.

https://www.ukaps.org/forum/attachments/b328bd67-c009-419e-875d-e050e545d656-jpeg.148392/

Very interesting.

As demonstrated we’ve seen deriving the majority of mineralisation through a compound like Gluconate that has a high affinity for biological action may not be immediately problematical for biology but it may swing the balance in favour of one specific activity that may or may not have negative outcomes with possible potential harmful consequences ie a bacterial bloom derived either through aerobic bacterial action scavenging excess oxygen to the detriment of higher life forms or anaerobic bacterial action that breaks down polluting compounds that may produce short lived toxic intermediary products (ie Hydrogen Sulphide) at too high a value.

Focusing attention on Calcium compounds and aiming to reduce Carbonate, Sulphate and Chloride these can be reduced by supplementing with other compounds, the Gluconate we have discovered has clouding issues through a bacterial process (? Only in the presence of Sulphates and anaerobes). Calcium Hydroxide can be used but because of its ability to strongly moderate pH then it needs to be neutralised with an acid, if the acid comes as a more complex compound with Calcium then it can boost desired calcium levels also, this could be Calcium Citrate. Calcium Acetate can moderate pH also being a base but it has an equilibrium reaction in aqueous solution forming Acetic acid thus neutralising the pH moderation to a degree. More Calcium acid can be found in Calcium Tannate which is a chelated form of Calcium. If we look further to chelated compounds Calcium we would have to include EDTA, DTPA, etc. All ways to add available Calcium and this is not limited to Calcium supplementation you can fit this to any other element as long as they are soluble at the pressures, temperatures and pH we see in a typical body of aquarium water.

I am not inclined to use anything that changes alkalinity/KH or pH, as I am ok with that as it is. But I will be ready to try alternatives. For now I am just going to stick to the CaSO4, but still use the relatively small amount of Mg Gluconate. Which didn't cause any adverse effects after my last WC.

Cheers,
Michael

 

[X3NiTH]

Does this essentially mean that if my tanks would not have had a high sulphate content (which they did, because I was using CaSO4 and MgSO4 for quite a while before trying out the Ca and Mg Gluconate) I wouldn't have gotten the Anaerobic reaction or bloom (assuming that is what it was) ? If so, the bloom could just be a short term reaction that would disappear after a couple of consecutive weekly water changes as the sulphate content gets lower?

Very possibly if aneorobes are involved and it’s temporary precipitate formation through biological action then the bloom may be much less apparent if Sulphates are limited. This would need to be tested.

I am not inclined to use anything that changes alkalinity/KH or pH, as I am ok with that as it is.

That’s totally fine.

Depending on what you want to achieve you can remineralise with novel compounds that in combination allow you to limit any one compound being dominant. In essence the creation of water where you have complete control over all relevant parameters (pH, GH, KH) where the compounds used are intermediary compounds generally present in the remains of end of life processes where they are seen by current life processes as available nutrition. The novel compounds discussed above contain carbon amongst other elements and it is the thing that’s in the shortest supply which all life processes need to grow tissue, supplying compounds that increase carbon availability personally I don’t see this as a bad thing, some folks add Gluteraldehyde based supplements which have biocidic properties to increase their carbon content in their tanks regularly, this is generally not seen as a bad thing either so there should be zero problem supplementing this with natural carbon containing compounds that may come with beneficial major ions like Calcium and Magnesium.

At the end of the day it is usually best to keep things simple which not only reduces potential for error and unforeseen side effects but also overall workload.

🙂

 

[MichaelJ]

Hi @X3NiTH just wanted to provide a quick up update on the Iron test... Seachem Iron Test consistently shows my iron level is slightly above 0 ppm - definitely below 0.1 ppm.... I am currently dosing ~0.55 ppm of Iron weekly... (actually the mid week dose yesterday) and there are zero signs of Iron deficiency in my tanks. I think either the test is flawed or the plants absorbed it in less than 24 hours - or I just did the test plain wrong (I am sure I followed every step precisely as prescribed, but I guess you never know).

EDIT: Updated the picture of the tank with an exposure that much better reflects the actual light level / intensity.



Cheers
Michael

 

[X3NiTH]

There is the chance that plants have uptaken the Iron but you have to take into account the chelate in use with Iron, the shortest lived common chelate in use with iron is the Gluconate, has a very short half life especially under light as it’s photosensitive. The other chelates EDTA and DTPA (photosensitive) and EDDHA longevity depends on the pH, EDTA starts to half life above pH 6.5 and DTPA at ph7, EDDHA is good up to pH 9 before it half life’s but it can tint water pink which can be undesirable.

I dose 0.1ppm FeGluconate and 0.05ppm FeDTPA together and 24hrs later I measure 0.025ppm which will be very likely all FeDTPA, still enough to cover the plants for the day until a new dose goes in 24hrs later. You always want some available to ensure no deficiencies, you appear to be accomplishing this with your current dose.

If you want to show what the tank looks like to the eye then post a pic with the exposure more to what your eyes see.

🙂

 

[MichaelJ]

There is the chance that plants have uptaken the Iron but you have to take into account the chelate in use with Iron, the shortest lived common chelate in use with iron is the Gluconate, has a very short half life especially under light as it’s photosensitive. The other chelates EDTA and DTPA (photosensitive) and EDDHA longevity depends on the pH, EDTA starts to half life above pH 6.5 and DTPA at ph7, EDDHA is good up to pH 9 before it half life’s but it can tint water pink which can be undesirable.

@X3NiTH Very interesting. I am not entirely sure I understand half-life in this context. When you say "starts to half life above pH 6.5" what does this imply? that it somehow "decay" and only half will be available to plants after a certain amount of time? My current trace fertilizer is an EDTA chelate and I am in the process of switching over to Nilocg Plantex CSM+B which also uses EDTA.

I dose 0.1ppm FeGluconate and 0.5ppm FeDTPA together and 24hrs later I measure 0.025ppm which will be very likely all FeDTPA, still enough to cover the plants for the day until a new dose goes in 24hrs later. You always want some available to ensure no deficiencies, you appear to be accomplishing this with your current dose.

How do you measure your Fe content? If I am reading this correctly, your dosing 0.6 ppm Fe each day?...that's almost 10 times EI weekly?

If you want to show what the tank looks like to the eye then post a pic with the exposure more to what your eyes see.

Controlling the exposure on an iPhone camera, especially when photographing a low light aquarium, is still way more difficult than it is supposed to be.

Cheers,
Michael

 

[X3NiTH]

If I am reading this correctly, your dosing 0.6 ppm Fe each day?...that's almost 10 times EI weekly?

Dang missed a 0.0 there, I’ve edited the above message to the correct value which should read 0.05ppm FeDTPA.

🙂

 

[MichaelJ]

@X3NiTH Ok, I guess the half life above is referring to the bio availability of the Fe being a function of water pH for non-photosensitive chelates... Now, what I don't understand is, why use EDTA if the Fe it's already half gone at pH 6.5 ?

Cheers,
Michael

 

[X3NiTH]

Now, what I don't understand is, why use EDTA if the Fe it's already half gone at pH 6.5 ?

When you dose at pH 6.5 it won’t immediately lose half its potency, it will take a period of time. If you are just over the pH threshold for stability of the EDTA chelate when you dose it then you can expect the half life period to be around 24hrs, the higher the pH then the shorter the half life period, I don’t have any graphs to show this effect but I’m pretty sure there will be one out there somewhere.

If your tank spends any significant time above pH 6.5 then you can supplement in a stronger chelate like DTPA so that the Iron is more available at the higher pH than if using EDTA alone.

I use a mixture of Iron Gluconate and DTPA, the Gluconate serves the plants Iron immediately after dosing until it’s gone due to it instability, the DTPA is being used so that there is still some available to the plants the next day when micro isn’t dosed.

🙂

 

[MichaelJ]

When you dose at pH 6.5 it won’t immediately lose half its potency, it will take a period of time. If you are just over the pH threshold for stability of the EDTA chelate when you dose it then you can expect the half life period to be around 24hrs, the higher the pH then the shorter the half life period, I don’t have any graphs to show this effect but I’m pretty sure there will be one out there somewhere.

Hi @X3NiTH OK, that makes sense... yes, it would be awesome to see a graph or a piece of math that shows this. I will look around and post if I find any.

If your tank spends any significant time above pH 6.5 then you can supplement in a stronger chelate like DTPA so that the Iron is more available at the higher pH than if using EDTA alone.

I use a mixture of Iron Gluconate and DTPA, the Gluconate serves the plants Iron immediately after dosing until it’s gone due to it instability, the DTPA is being used so that there is still some available to the plants the next day when micro isn’t dosed.

My pH in both my tanks is hovering around 7.4 so I guess its a fairly quick fall off when I dose. Thanks for the education on this.

Cheers,
Michael