Diy Ferts - Micro Questions

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fa4960

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I have a low tech, lightly planted tank. It has been running for about 10 months now and for the last 6 months or so I have been dosing a liquid fertiliser bought locally. Results have been rather good with increased plant growth but as the water volume is 1500L / 375G it is rather expensive with weekly WC and it is actually keeping me back from doing WC every 4 - 5 days.

This is what I have been dosing:
Micro- Dosing is 0.5cc per 10 liter water
Mg Magnesium 0.24 ppm mg/l
S Sulfur 0.5 ppm mg/l
Zn Zinc 0.03 ppm mg/l
Cu Copper 0.02 ppm mg/l
Mn Manganese 0.06 ppm mg/l
B Boron 0.03 ppm mg/l
Mo Molybdenum 0.005 ppm mg/l
Fe Iron 0.06 ppm mg/l
Macro 1 (Potassium)- Dosing is 1cc per 10 liter water
K Potassium 10 ppm mg/l
S Sulfur 4.5 ppm mg/l
Macro 2 (Phosphorus)- Dosing is 1cc per 10 liter water
K Potassium 0.16 ppm mg/l
P Phosphorus 0.13 ppm mg/l
Cu Copper 0.01 ppm mg/l
Macro 3 (Nitrogen) - Dosing is 1cc per 10 liter water
K Potassium 0.37 ppm mg/l
N Nitrogen 1.82 ppm mg/l
Ca Calcium 0.6 ppm mg/l

1cc = 1ml = 0.033814 US fluid ounce

It is pre-mixed so I didn't control the components or the amount in each bottle. As I have high Nitrate levels I have stopped dosing Nitrogen for the last 1 - 2 months and it seems to have no effect on the plants as there's clearly more than enough already. I have some algae problems but I believe it is due to imbalance between the nutrients with way too much Nitrate. I am about to make a DIY algae scrubber to solve that issue. I am aware that the scrubber will compete with the plants for nutrients but I don't mind dosing a little extra ferts if I have them at low cost.

So I want to mix my own fertilizer. As it is not an option for me to import dry fertilizer from e.g USA I need to see what I can get local.

I have watched the videos on YouTube on DIY Ferts from Aquapros and I think the Macros are quite straight forward so it's more the micro's that may be a challenge.

What's your view on the Micro mix above - in terms of components and also the amounts?
Any other comments and experiences are also very welcome.
 
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Most micro mixes are based on plantex csm+b... might want to look it up for reference
Great idea, thanks.

Went to rotalabutterfly.com and checked out CSM+B based on EI and a Fe target of 0.2 and it came back with the following breakdown:
Element ppm/degree
Fe 0.2
Mn 0.057
Cu 0.003
Mg 0.043
Zn 0.011
Mo 0.002
B 0.025
dGH 0.01

These seem to be percentages, except Boron that varies depending on who has added it to the CSM base mix.
Fe 6.53%
Mn 1.87%
Mg 1.40%
Zn 0.37%
Cu 0.09%
Mo 0.05%
B 1.18%

So maybe this will be my target.
 

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What's your view on the Micro mix above - in terms of components and also the amounts?
The proportions look good I think. Jocelyn is right that using Plantex CSM+B as a template can be helpful. There are others, such as Rexolin APN and some people try and match Flourish as well.

In terms of its subsidiary components, that can be a challenge, depending on what you can source locally in non-commercial quantities (i.e. trying to find someone who doesn't want to sell you the chemical fertiliser by 25 kg sacks).

Usually it's a combination of the following:

Fe: EDTA (if pH at or below 6.5) or DTPA (if pH above 6.5)
Mn: MnSO4. Usually it's monohydrate for fertilisers, but sometimes only heptahydrate (7H20) is available
Mg: MgSO4. Generally bought as epsom salts, which is MgSO4.7H20
Zn: Either ZnSO4 or ZnO
Cu: CuSO4
Mo: Molybdic acid (written variously as H2MoO4 or MoO3.H2O)
B: Either borax or boric acid

It can be the case that you can buy a locally available trace element mix, and then simply add additional Fe, Mg (and whatever else) to change the proportions a bit. This avoids the necessity of having to purchase all chemical compounds, particularly the CuSO4 and boric acid (on account of their toxicity).
 
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I found a pre-mixed micro nutrient pack called NIC spray (despite being dry...) but it is not really meant for "aquaponic" but is fine for hydroponics:

NIC-SPRAY

High Quality Fully water soluble. Chelated Micronutrient Mixture.

Chelate-EDTA : MgO 7.29%, Fe 1.90%, Mn 1.94% Cu 2.08%, Zn 1.90%, B 2.17% Mo 0.024%, Ni 0.05%

Unfortunately I don't see it working with the mix listed, also the fact that my PH is 8.2 I think an EDTA chelate will leave very little left for the plants. I think I need a FDTA as minimum but will probably avoid the EDDHA chelate for iron as it seems to stain the water (and everything else) pink even at small doses.

@Minnowette What do you think?
 

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@Minnowette What do you think?
It's a difficult call. The copper is about 23 times higher than in aquarium ferts, and that might call for too much mixing in attempting to correct it to a lesser concentration.

I find that if you can't source a micro fert mix with the right chelated iron, it's perfectly fine to use it and add the right chelated iron as a separate stand alone fert. For example I use DTPA chelated iron and Flourish (where the iron is in the form of ferrous gluconate).

Lots of countries have various restrictions on the sale and supply of fertiliser products (e.g. potassium nitrate can't be shipped via ordinary post in Australia as it's classified as a dangerous/explosive substance), but it might be worth seeing whether you can order a bulk supply of Plantex CSM+B from the US. Or you can investigate what options are available to other planted tank aquarists in South-East and East Asia and see if it might be possible to order a shipment.
 
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@Minnowette You seem to know a lot about this topic so hopefully you don't mind another question...

When googling EDDHA Fe6 there seems to be different versions and the difference is the Ortho-Ortho Content, e.g.
EDDHA Fe6% O-O 4.8
EDDHA Fe6% O-O 3.6
EDDHA Fe6% O-O 1.8
etc.

All of them are listed as 100% water soluble

I have found a source of EDDHA Fe6% locally but there's no mention of O-O Content - is it important?
 

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Ortho-Ortho Content
I wouldn't want to misrepresent as a chemist or botanist (definitely not!), just an interested hobbyist with perhaps far too much free time!

Short answer: Doesn't matter much for our purposes I think. I can't remember ever coming across an aquatic plant fertiliser that mentioned o-o, o-p or p-p.

Long answer: I have come across these terms before in terrestrial botany. From what I remember, o-o, o-p and p-p are isomer positional designations, i.e. they clarify where the hydroxyl groups (OH) are positioned in different EDDHA isomers.

The following diagram shows some examples of the differing position of hydroxyls in a few EDDHA isomers.

HJmDIvG.png


To an extent, it's important as the arrangement of hydroxyl groups determine the reactions that can take place. But as I mentioned, given that these are so rarely mentioned in aquatic plant fertilisers, it's likely the case that it isn't important for our purposes.
 

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It is quite possible that only the ortho-ortho isomer allows iron binding between the six sites (two amines, two carboxyls and the two phenolic groups) since only o-o isomer has all 6 groups positioned close together.
 
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It is quite possible that only the ortho-ortho isomer allows iron binding between the six sites (two amines, two carboxyls and the two phenolic groups) since only o-o isomer has all 6 groups positioned close together.
Based on what I see available for sale as water soluble you could very well be correct. So far I have only seen O-O versions.
 
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Okay, I have now managed to find almost everything locally in small quantities, except for Molybdenum.

I found 3 different versions of chelated iron and plan for either EDDHA or DTPA.
EDTA E-FE13
EDDHA Fe6
DTPA D-Fe11

I also managed to find FeSO4.7H2O Iron (II) Sulfate but then I won't have the benefits of the chelates and hence I guess most of the iron won't be available to the plants with my PH at 8.2?

I found the following other micronutrients

MgSO4 Magnesium Sulfate
ZnSO4.H2O Zinc (II) Sulfate
CuSO4.5H2O Copper (III) Sulfate
MnSO4.H2O Manganese (II) Sulfate
H3BO3 Boric Acid

Can I mix these together with the chelated iron and if yes will they also benefit from the chelates or am I better off keeping the chelated iron separately?

In other words, what would you recommend that I do with the above availability of chemicals? Are there other chemical compositions besides the ones listed that would be better?

PS: As I am writing this I managed to find yet another local supplier with many more chemical compositions and also Na2MoO4.2H2O Sodium molybdate dihydrate
 

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I also managed to find FeSO4.7H2O Iron (II) Sulfate but then I won't have the benefits of the chelates and hence I guess most of the iron won't be available to the plants with my at 8.2?
Other nutrients can indeed benefit from the chelate. Whether you mix it together or separately won't - in my line of thinking - particularly make a difference as it all ends up as a single solution when you dose it in the tank. Most people mix it in with the rest of their micros as a matter of a convenience and a way to benchmark their micro dosing (i.e. dose based according to iron concentration, and the other micros should be in sufficient concentration).

In other words, what would you recommend that I do with the above availability of chemicals? Are there other chemical compositions besides the ones listed that would be better?

PS: As I am writing this I managed to find yet another local supplier with many more chemical compositions and also Na2MoO4.2H2O Sodium molybdate dihydrate
Sodium molybdate works fine, so too does ammonium molybdate.

I think you've done a marvellous job in assembling all the compositional compounds! They all look appropriate to me. I think now it's just a matter of purchasing them and mixing together either in dry form or as a solution. Of course, a milligram scale will be very useful (almost necessary I would say).

I assume you're aware of this (but just in case you aren't), you'll need to convert Plantex CSM+B's percentage of a nutrient into a mass that takes into account the molar mass of the particular compound you're using.

So 1.4% Mg (pert Plantex CSM+B) in 100 grams of your fert mix would not mean 1.4 grams of MgSO4, but 5.53 grams.
 
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Other nutrients can indeed benefit from the chelate. Whether you mix it together or separately won't - in my line of thinking - particularly make a difference as it all ends up as a single solution when you dose it in the tank. Most people mix it in with the rest of their micros as a matter of a convenience and a way to benchmark their micro dosing (i.e. dose based according to iron concentration, and the other micros should be in sufficient concentration).



Sodium molybdate works fine, so too does ammonium molybdate.

I think you've done a marvellous job in assembling all the compositional compounds! They all look appropriate to me. I think now it's just a matter of purchasing them and mixing together either in dry form or as a solution. Of course, a milligram scale will be very useful (almost necessary I would say).

I assume you're aware of this (but just in case you aren't), you'll need to convert Plantex CSM+B's percentage of a nutrient into a mass that takes into account the molar mass of the particular compound you're using.

So 1.4% Mg (pert Plantex CSM+B) in 100 grams of your fert mix would not mean 1.4 grams of MgSO4, but 5.53 grams.
I am aware that I need to convert but haven't got my head around how yet. I know the Molecular weight of MgSO4 is 120.366 g/mol but please do enlighten me on your calculation.
 
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Okay, got myself into the calculations. When looking for a target ppm for Mg there's a huge difference between Rotala Butterfly's "EI low light / weekly" recommendation of 5 ppm and CSM+B's outcome of only 0.043 ppm (based on Fe target of 0.2). Any idea why there such a difference? FYI: Rotala Butterfly Fe recommendation is 0.1 for Fe.

I also noticed that is unlikely that I will actually get MgSO4 but rather MgSO4.7H2O despite all the suppliers only listing the former. So based on this I did a manual calculation:
20180912_161314.jpg
Fortunately my calculation gives the same result as Rotala Butterfly. So based on this I need 507 grams of Epsom salt for every liter of water in my solution and I need to doze 150ml weekly to obtain 5 ppm in my 1500 liter tank.

That's a lot of Epsom salt I think? Why is the RB recommendation so high or have I misunderstood the Mg amount in CSM+B?
 

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I am aware that I need to convert but haven't got my head around how yet. I know the Molecular weight of MgSO4 is 120.366 g/mol but please do enlighten me on your calculation.
Oops, my initial calculation was incorrect: I divided molar mass Mg by molar mass SO4. It should be: molar mass Mg divided by molar mass MgSO4 = 24.305 / 120.366 = 0.2019. So 20.19% of any given mass of MgSO4 will be in the form of Mg.

Mass of MgSo4 required to arrive at a 1.4% concentration of Mg in 100 grams of fert = 1.4 grams * (1 / 0.2019) = 6.93 grams.

The same formula can also be applied for magnesium sulfate heptahydrate.

That's a lot of Epsom salt I think? Why is the RB recommendation so high or have I misunderstood the Mg amount in CSM+B?
No, you're right. Generally most of these pre-mixed micro ferts have rather low calcium and magnesium based on the implicit understanding that your source water has sufficient Mg and Ca. In most cases, most people adjust their GH (i.e. Mg/Ca concentration) separately from the rest of their micro ferts using a standalone GH Booster (typically CaSo4 and MgSO4.7H2O) or they'll adjust their Mg alone with MgSO4.7H2O.

The little MgSo4 that is added in these ferts, I think, is done so as a matter of convention.

This is why your CSM+B has a low Mg concentration while RB has listed a higher ppm target listed: the former assumes your source water has enough, the latter doesn't.
 

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I need 507 grams of for every liter of water in my solution and I need to doze 150ml weekly to obtain 5 ppm in my 1500 liter tank.
In addition, you can use a slightly more concentrated solution if dosing MgSO4.H2O separately from your other micro ferts. The solubility of MgSO4.H2O at 20 degrees Celsius is 113 grams per 100 ml water, so you can use a 75 ml dosing amount (which would 90% of the compound's saturation) and a total mass of 1,014.13 grams MgSO4.7H2O in 1,000 ml water.

To help aid solubility in concentrated solutions, I generally heat the RO/distilled water for a little bit in the microwave.

In addition, I suspect another reason why Mg and Ca is added as a separate supplement is that the water solvent would rapidly reach the saturation point because of their larger dosing requirements (e.g. 5 ppm Mg vs 0.2 ppm Fe): it's probably easier to just dose MgSO4.7H2O separately. Further to that, CaSO4 has very low solubility in water (0.24 g per 100 ml water at 20C) which is likely why it's rarely added to these pre-mixed ferts.
 

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This is not intended as criticism of or argument against anything written above.

I probably learned enough science and math 50-60 years ago to follow Minnowette into this pool but I druther swim in shallower water. My strategy is to take dosing advice specific to a particular compound from a trusted supplier or advisor. So references to molar mass were brand new to me and when I first saw them in a bullet point list that began with Easy Dosing Calculations, I assumed the post was meant to be funny.

Minnowette is certainly one of the sources of advice I would turn to. The folks you bought the nutrient from will often recommend a specific dosing rate for the product they sell. Another good information source is a guy named Nate Storey. He made some excellent YouTube videos a few years ago and although he has since moved on, the vids are still available through YouTube's BrightAgrotech Channel. There are 16 in the subgroup called Aquaponic Nutrient Management that I've found particularly useful and Iron in Aquaponics Part 1, Iron in Aquaponics Part 2, and Adding Epsom Salt to Aquaponic Systems are particularly relevant to the discussion in this thread.

Once again, I'm not contradicting anything or anyone. I'm simply offering a different perspective in case somebody reading this needs a leg up getting to a target parts per million, or milligrams per liter.
 
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@skilletlicker I appreciate all comments on this topic. The more discussion the better in my view.

One main reason for me going down this route is the lack of local availability of pre-mixed dry ferts. Even if I was prepared to pay for Nilocg dry ferts they can be shipped out to me in Thailand. Second reason is the amount needed with weekly WC's in my 1500 Liter (375G) aquarium plus sump. I have bought some pre-mixed solutions locally but it's just too expensive in the long run and this company refuses to sell me dry compound of their mixes.....so there's no sellers to look to for advice, hence looking at CSM+B and others to get some ideas for mix.

I can fairly easily get the base chemicals from either chemical, hydroponics or plant fertilizer companies, all in 500g - 1 kg packs at really low prices, i.e. 1 kg KNO3 for USD 1.5 and most of the micros from USD 5 - 10 for 500g which in most cases will last me many months if not years.

I am almost done doing my calculations and doze decisions and I will post them here shortly. Would be very happy to get your input on this also.
 
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My brown glass bottles have arrived. 3 X 2500 ml and 2 X 1000 ml. That was the rest stock of this particular supplier so now I need to see how I best get them to use.

Most likely 3 big macro bottles, although I will probably not doze Nitrogen until I see my Nitrates drop low. Then maybe two micro, with Iron DTPA chelate in one and the rest in the other....

20180923_131844.jpg
 

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Very exciting! On account of the bottle sizes, it's worth having a think - if you haven't already - about different ways of preserving the mixtures (especially the micro mix and iron) to avoid mould growth.

Refrigeration is often suggested, but I skirt the idea as I would hate to confuse a bottle of iron chelate for one of milk if ever I wake up thirsty at night.

I have read of others using 10-20 ml Excel or hydrochloric acid to 500 ml of their ferts as a preservative, and it seems to be a fairly common practice.
 
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