Nice to meet you all from Indonesia (and an overview on my plant journey)

[Steve Johnson]

Hi Adi,

First of all, you're nailing it on the pH calibration procedures, so bravo! Since I now have the weights of the GrowMore, KARATE PLUS, and Magnit, I'll do some serious numbers-crunching and get back to you with the dilutions ASAP.

Based on your water test results, it may not be possible to completely neutralize KH by the time the watering solution in your mix dries out -- that's a critical limitation of trying to guess what will happen based on changes in a jarful of test water. (By the way, I'm coming up with the same results after 7 days in my test jar.) But going from 180 to 40 ppm KH is 80% neutralization, pretty darn good capture of Ca and Mg going to your plants. Unfortunately you'll have to go through the whole testing exercise again once you whip up a 50-liter batch of water diluted with GrowMore, KARATE PLUS, Magnit, and potassium sulfate per the dilutions I give you. If that batch is pure rainwater or a mix of rainwater and tap water, there's no point in running the test until you can do it with 50 liters of tap water. The reason -- we need to determine if you should add citric acid to your watering solution, and if so, how much. With pure rainwater or a rainwater/tap water mix, I'll recommend that you avoid adding citric acid.

[Wiandry Adi]

Hi Adi,

First of all, you're nailing it on the pH calibration procedures, so bravo! Since I now have the weights of the GrowMore, KARATE PLUS, and Magnit, I'll do some serious numbers-crunching and get back to you with the dilutions ASAP.

Based on your water test results, it may not be possible to completely neutralize KH by the time the watering solution in your mix dries out -- that's a critical limitation of trying to guess what will happen based on changes in a jarful of test water. (By the way, I'm coming up with the same results after 7 days in my test jar.) But going from 180 to 40 ppm KH is 80% neutralization, pretty darn good capture of Ca and Mg going to your plants. Unfortunately you'll have to go through the whole testing exercise again once you whip up a 50-liter batch of water diluted with GrowMore, KARATE PLUS, Magnit, and potassium sulfate per the dilutions I give you. If that batch is pure rainwater or a mix of rainwater and tap water, there's no point in running the test until you can do it with 50 liters of tap water. The reason -- we need to determine if you should add citric acid to your watering solution, and if so, how much. With pure rainwater or a rainwater/tap water mix, I'll recommend that you avoid adding citric acid.

I'll kindly wait for the results. Well, I'll check if I have time this weekend to conduct these undertakings. I think I'll keep using tap water for the sake of ease on gathering the results (esp. regarding KH)... if it's not raining again. It's not because I'll use rainwater; it's because I have to dial back on the watering when it starts raining more, about two or three weeks per watering, depending on temperature, sunlight exposure, and humidity.

[jerrytheplater]

CaCO3 (the primary carbonate) contains 40% calcium, but the complicating factor here is that all carbonates are measured as though it's only calcium carbonate. Magnesium carbonate makes up about 1/3 of the carbonates in tap water, so we'll try this:

• 180 ppm KH = 120 ppm CaCO3 x 0.4 = 48 ppm Ca. MgCO3 contains 28.57% Mg. 60 ppm MgCO3 x .2857 = 17 ppm Mg.

The first red highlight is not a safe assumption to make Steve. The makeup of carbonates in water varies with the source of the water and the local geology that that water contacts. As an example, the water in Lake Tanganyika has a Mg:Ca ratio of 3-4:1. The opposite of the fertilizer solutions used. The amount of Ca and Mg in tap water is something that has to be tested for, not assumed.

The second red highlight would be true if that concentration of MgCO3 was made up as a solution in your home or lab. But, it is from the hardness testing where the full terminology for the test result is Magnesium Hardness in ppm CaCO3. A full explanation of why the two are not the same requires you to know that the test reacts with calcium and magnesium in a molar relationship. One mole of Calcium is equal to one mole of Magnesium in the reaction.

The correct conversion of Magnesium hardness in ppm CaCO3 to ppm Mg is to multiply the Mg Hardness in ppm CaCO3 by 0.24 and then you will get the correct value.

Proof? I am really too lazy to think it out again, and too lazy to find where I've written it down. But, here it is on the directions for the LaMotte Hardness test kit that I have: https://lamotte.com/amfile/file/downloa ... oduct/112/ Scroll down to the second to last page and you'll see the numbers they give.

[jerrytheplater]

I just went back and read your posts again Steve where you are quoting the Hach information. Are you saying that your tap water has an Alkalinity of 180 ppm CaCO3 and your General Hardness (Ca and Mg) is 75 ppm CaCO3? That means assuming your Ca and Mg are bicarbonates you still have other bicarbonates in your water to make up the 180 ppm CaCO3 Alkalinity. Your water seems to be made up of Ca and Mg bicarbonates (because the pH is lower than 10.3) and other bicarbonates, maybe Potassium or Sodium bicarbonates, or even Borates.

You must have posted this above, but I am not remembering where.

[Steve Johnson]

CaCO3 (the primary carbonate) contains 40% calcium, but the complicating factor here is that all carbonates are measured as though it's only calcium carbonate. Magnesium carbonate makes up about 1/3 of the carbonates in tap water...

The first red highlight is not a safe assumption to make Steve. The makeup of carbonates in water varies with the source of the water and the local geology that that water contacts. As an example, the water in Lake Tanganyika has a Mg:Ca ratio of 3-4:1. The opposite of the fertilizer solutions used. The amount of Ca and Mg in tap water is something that has to be tested for, not assumed.

The statement you highlighted in red comes from Vernier Science Education (https://www.vernier.com/experiment/wqv- ... -hardness/):

• "On average, magnesium hardness represents about 1/3 of total hardness and calcium hardness about 2/3."

This is a general statement, and I do realize that whether it applies or not will depend on local geology and water sources. If acidified tap water was the only source of Ca and Mg going to the roots of my cacti, I might have it tested for the amounts of both. However, they're getting Ca and Mg from the TPS CalMag supplement too -- from the greatly improved results I've seen this year, knowing the exact amounts of Ca and Mg they're getting from my acidified tap water may be interesting, but not important. I don't think it would be important for Adi either. This brings us to something Mike said on page 6 of the thread:

We are not doing lab experiments and writing scientific papers.

I just went back and read your posts again Steve where you are quoting the Hach information. Are you saying that your tap water has an Alkalinity of 180 ppm CaCO3 and your General Hardness (Ca and Mg) is 75 ppm CaCO3? That means assuming your Ca and Mg are bicarbonates you still have other bicarbonates in your water to make up the 180 ppm CaCO3 Alkalinity. Your water seems to be made up of Ca and Mg bicarbonates (because the pH is lower than 10.3) and other bicarbonates, maybe Potassium or Sodium bicarbonates, or even Borates.

Can't remember the source, but I read somewhere online that potassium and sodium bicarbonates, and borates are a very small percentage of total bicarbonates. Unless someone can show us convincing evidence that sodium bicarbonate in tap water poses a problem for cacti, it's not a matter to be concerned about.

[jerrytheplater]

I would be interested to know how they came up with that average. My water comes from reservoirs with granite and gneiss under them. Very little CaCO3 in the watershed. NYC water from the Catskills is close to RO and does not require any treatment to speak of. I tasted the water out of a water fountain at Yankee Stadium years ago and was astounded by the great taste. A member of the Aquatic Gardening club I belong to lives in Yonkers, NY and has that water. She can keep Discus in her tap water!! (If that means anything to you. Aquarium Hobbyists will understand.) I think the TDS of her water is somewhere around 20-30 ppm.

When I mentioned the bicarbonates it was because you are using your Alkalinity value of 180 ppm as if it is the source of your Ca and Mg. That is incorrect. You use 2/3 of it (120 ppm CaCO3) and 1/3 of it (60 ppm MgCO3) in the calculations. Your Ca and Mg makes up your 75 ppm GH, and also contributes in your Alkalinity by the bicarbonates. If you want to use that 2/3:1/3 rule that would be 50 ppm CaCO3 and 25 ppm MgCO3. The excess which makes up your Alkalinity is some type of bicarbonate or borate. (I'm not saying there is any problem with those bicarbonates either, just stating the facts. You are neutralizing them by acidification.) I say borate because I know borax is/was mined out in CA, but have no idea if it is near you. Borates very seldom are found in drinking water-but you do live in the state where it is mined. And it will react in an Alkalinity test. I hope you don't have it in your water.

[Steve Johnson]

When I mentioned the bicarbonates it was because you are using your Alkalinity value of 180 ppm as if it is the source of your Ca and Mg. That is incorrect. You use 2/3 of it (120 ppm CaCO3) and 1/3 of it (60 ppm MgCO3) in the calculations. Your Ca and Mg makes up your 75 ppm GH, and also contributes in your Alkalinity by the bicarbonates. If you want to use that 2/3:1/3 rule that would be 50 ppm CaCO3 and 25 ppm MgCO3. The excess which makes up your Alkalinity is some type of bicarbonate or borate. (I'm not saying there is any problem with those bicarbonates either, just stating the facts. You are neutralizing them by acidification.) I say borate because I know borax is/was mined out in CA, but have no idea if it is near you. Borates very seldom are found in drinking water-but you do live in the state where it is mined. And it will react in an Alkalinity test. I hope you don't have it in your water.

You might've forgotten about the fact that the aquarium test strips I'm using test for carbonate hardness (KH) as well as alkalinity, so I'm not relying solely on alkalinity. I tested my tap water before I added ferts, supplements, and vinegar -- the strip read 180 ppm KH, 180 ppm alkalinity, and 75 ppm total hardness (GH). After 3 days in the test jar, KH went down to 80 ppm, calcium and magnesium acetates floating around in the water showing that the carbonates were being neutralized. Those acetates make Ca and Mg available for uptake by the roots. Even if complete neutralization isn't possible by the time watering solution in the mix dries out, a good amount of Ca and Mg is being captured for use by my cacti. How much of it is something I've been trying to determine, but more as a matter of curiosity. Which brings me to this...

I made an assumption about the idea that plants can't take up Ca or Mg from bicarbonates. Was I wrong? Don't know if the following article answers the question, but this may be interesting:

https://link.springer.com/chapter/10.10 ... 9-4125-4_2

A key take-away: "Based on the comprehensive impact of bicarbonate on many physiological and biochemical processes, bicarbonate is no less important to plants than carbon dioxide."

Jerry -- borax was mined in Inyo and Kern counties, but that's a whole lotta miles away from where I live, so I seriously doubt that borates are in my tap water.

[Steve Johnson]

Okay, Adi -- the numbers have been duly crunched, so here you go...

Add the following to 50 liters of water:

• GrowMore 1/2 tsp. x 3
  KARATE PLUS 1/2 tsp.
  PUPUK Magnit 1/2 tsp.
  Potassium sulfate 1/2 tsp. x 3

What you'll get in the watering solution:

• 7 ppm Ammonium N, 16 ppm Urea N, 28 ppm Nitrate N, total N = 51 ppm

• 14 ppm P

• 70 ppm K

• 16 ppm Ca

• 6 ppm Mg

• 18 ppm S

The NPK ratio is 1-0.27-1.37, so P and K are well within optimal range, and the NPK dosages per feeding are quite good. Wish I could've increased the amounts of Ca and Mg, but that's the best we can do. Bear in mind that your cacti and succulents can get a good amount of Ca and Mg from the tap water, so every little bit helps -- even the gypsum you add to your pots. Whenever you water with rainwater, the Ca and Mg in the KARATE PLUS and Magnit will be sufficient.

I'm highly confident that you will need to add citric acid when you make 50-liter batches of tap water diluted with the ferts and potassium sulfate. The steps are:

• Test the pH of the watering solution after you add the ferts and potassium sulfate.

• Add citric acid in half-teaspoon increments one increment at a time, and test the pH with each increment.

• Once you get close to the target pH of 6.0, go 1/4 tsp. at a time until you hit the target. If it's a little bit below (say 5.9), no worries.

• "Sneaking up" on the target pH does take some patience, but if you write down the total amount of citric acid you used, you won't have to keep going through the exercise.

A couple of items for your attention. First, we know that pH rebounds up as weak acid in the watering solution neutralizes carbonates -- calcium citrate and magnesium citrate are the reaction products that get Ca and Mg to the roots of your plants. And your acidic mix helps in the process, so watering solution acidified to 6.0 is fine for both of your mix types.

And finally, remember this?

Mulders_chart.jpg (87.83 KiB) Viewed 126809 times

Mulder's chart was missing something -- Mo increases N availability from nitrate through the conversion process as I mentioned in a previous post. Relying on just one form of N in a fertilizer will lead to problems, so you have a good balance between Ammonium N-Urea N and Nitrate N. Unfortunately the amount of Mo in GrowMore is so small that it might as well not be there, and I highly recommend that you add a little bit of sodium molybdate to your watering solution. You won't be able to add it directly to your watering solution, so I'll crunch a few more numbers and come up with a sodium molybdate stock solution you can make, then add -- you guessed it -- 1/2 tsp. per 50 liters of watering solution.

[Wiandry Adi]

Okay, Adi -- the numbers have been duly crunched, so here you go...

Add the following to 50 liters of water:

• GrowMore 1/2 tsp. x 3
  KARATE PLUS 1/2 tsp.
  PUPUK Magnit 1/2 tsp.
  Potassium sulfate 1/2 tsp. x 3

What you'll get in the watering solution:

• 7 ppm Ammonium N, 16 ppm Urea N, 28 ppm Nitrate N, total N = 51 ppm

• 14 ppm P

• 70 ppm K

• 16 ppm Ca

• 6 ppm Mg

• 18 ppm S

The NPK ratio is 1-0.27-1.37, so P and K are well within optimal range, and the NPK dosages per feeding are quite good. Wish I could've increased the amounts of Ca and Mg, but that's the best we can do. Bear in mind that your cacti and succulents can get a good amount of Ca and Mg from the tap water, so every little bit helps -- even the gypsum you add to your pots. Whenever you water with rainwater, the Ca and Mg in the KARATE PLUS and Magnit will be sufficient.

I'm highly confident that you will need to add citric acid when you make 50-liter batches of tap water diluted with the ferts and potassium sulfate. The steps are:

• Test the pH of the watering solution after you add the ferts and potassium sulfate.

• Add citric acid in half-teaspoon increments one increment at a time, and test the pH with each increment.

• Once you get close to the target pH of 6.0, go 1/4 tsp. at a time until you hit the target. If it's a little bit below (say 5.9), no worries.

• "Sneaking up" on the target pH does take some patience, but if you write down the total amount of citric acid you used, you won't have to keep going through the exercise.

A couple of items for your attention. First, we know that pH rebounds up as weak acid in the watering solution neutralizes carbonates -- calcium citrate and magnesium citrate are the reaction products that get Ca and Mg to the roots of your plants. And your acidic mix helps in the process, so watering solution acidified to 6.0 is fine for both of your mix types.

And finally, remember this?

Mulders_chart.jpg

Mulder's chart was missing something -- Mo increases N availability from nitrate through the conversion process as I mentioned in a previous post. Relying on just one form of N in a fertilizer will lead to problems, so you have a good balance between Ammonium N-Urea N and Nitrate N. Unfortunately the amount of Mo in GrowMore is so small that it might as well not be there, and I highly recommend that you add a little bit of sodium molybdate to your watering solution. You won't be able to add it directly to your watering solution, so I'll crunch a few more numbers and come up with a sodium molybdate stock solution you can make, then add -- you guessed it -- 1/2 tsp. per 50 liters of watering solution.

Thanks a lot for your calculation, Steve! I'll put this to my fert schedule and see if I can get start doing the pH rebound test this week. Speaking of molybdenum, I finally found a seller which sells ammonium molybdate at a reasonable price (still, only at 10 gr/order, but it's a progress from last time) so maybe you can include ammonium molybdate one as well.

I would be interested to know how they came up with that average. My water comes from reservoirs with granite and gneiss under them. Very little CaCO3 in the watershed. NYC water from the Catskills is close to RO and does not require any treatment to speak of. I tasted the water out of a water fountain at Yankee Stadium years ago and was astounded by the great taste. A member of the Aquatic Gardening club I belong to lives in Yonkers, NY and has that water. She can keep Discus in her tap water!! (If that means anything to you. Aquarium Hobbyists will understand.) I think the TDS of her water is somewhere around 20-30 ppm.

When I mentioned the bicarbonates it was because you are using your Alkalinity value of 180 ppm as if it is the source of your Ca and Mg. That is incorrect. You use 2/3 of it (120 ppm CaCO3) and 1/3 of it (60 ppm MgCO3) in the calculations. Your Ca and Mg makes up your 75 ppm GH, and also contributes in your Alkalinity by the bicarbonates. If you want to use that 2/3:1/3 rule that would be 50 ppm CaCO3 and 25 ppm MgCO3. The excess which makes up your Alkalinity is some type of bicarbonate or borate. (I'm not saying there is any problem with those bicarbonates either, just stating the facts. You are neutralizing them by acidification.) I say borate because I know borax is/was mined out in CA, but have no idea if it is near you. Borates very seldom are found in drinking water-but you do live in the state where it is mined. And it will react in an Alkalinity test. I hope you don't have it in your water.

OK, that's an interesting insight. I do remember one time I kept discus years ago and I gotta say it's one of the hardest task I ever did - so I switched to catfishes that lived longer (I'm not doing aquascaping at the moment, by the way). Also I'll keep an eye out for any 'silly' substrates that occur in my tap water. Borax made a major headline here in Indonesia and it had huge impact on how I perceive that compound, but if I'm not mistaken, last time I saw borax is not on the list of the water test result from neighboring city.

[Steve Johnson]

Hi Adi,

Understandable why you'd rather not go with sodium molybdate. The different ammonium molybdates are Ammonium orthomolybdate, (NH4)2MoO4; Ammonium heptamolybdate, (NH4)6Mo7O24 (usually encountered as the tetrahydrate); Ammonium phosphomolybdate, (NH4)3PMo12O40; and Ammonium tetrathiomolybdate, (NH4)2MoS4 (this chemical is used for analysis of chloride in a solution, so probably not the one you'll get). Ammonium heptamolybdate tetrahydrate is the one commonly used as a fertilizer supplement, so please verify if that's what you'll get. This is important, since the percentage of Mo depends on the ammonium molybdate chemical formula being used. Once I know what you'll get, I can work on the proper dilution.

[Wiandry Adi]

Hi Steve,

I'm once again bewildered by the fact that there's more than one form of ammonium molybdate and how expensive they can be even for 500 gr / 1 lbs of them (I have to say even compared to your ferts, this compound is interstellar-ly more expensive). Thankfully, there are a few sellers who sold them as 10 gr repackings. Knowing how few we need molybdenum in our ferts, I guess 20 gr will hopefully do more than enough.

OK, so you're recommending ammonium heptamolybdate tetrahydrate. Here's the reference that I found: https://www.merckmillipore.com/ID/id/pr ... gle.com%2F

Is that it? So I shall find something that reads [ (NH₄)₆Mo₇O₂₄ * 4 H₂O ] or [ H₂₄Mo₇N₆O₂₄ * 4 H₂O ]. I also do a quick Google search and it stated ammonium molybdate is generally water-soluble, but we'll see that after I got some of this 'treasure'!

[Steve Johnson]

OK, so you're recommending ammonium heptamolybdate tetrahydrate. Here's the reference that I found: https://www.merckmillipore.com/ID/id/pr ... gle.com%2F

Is that it?

Yes, that's it. I also see it here...

https://www.direct2farmer.com/3425/ammonium-molybdate/

...so I'm sure that's the ammonium molybdate you'll get from the seller you found. I'm having trouble coming up with the right dilution, so I'll need to work on it some more. Please wait until I figure out the stock solution and the amount that should go into your watering solution.

[Steve Johnson]

Hi Adi,

Okay, I quadruple-check the numbers, so here are some instructions:

• You'll need a 1-liter bottle for your ammonium molybdate stock solution. If you don't already have one, go here:
  
  https://www.tokopedia.com/search?q=boto ... 2.02.01.01
  
  By the way, I'm kinda liking Tokopedia. Maybe the next best thing to Amazon in Indonesia?

• Break out your scale, measure 1 gram ammonium molybdate and dilute it in a liter of distilled water or rainwater (not tap water!).

• Buy a graduated measuring cup. If you don't already have one, go here:
  
  https://www.tokopedia.com/search?st=pro ... ource=home
  
  If you want to get all scientific, you can even buy a glass beaker or two or five (lab coat not included ).

• Add 50 milliliters stock solution per 50 liters of watering solution.

Now we'll go through the numbers...

1 gram ammonium molybdate contains 0.53 g Mo
0.53 g/l = 530 ppm
1 ml = 0.53 ppm
0.53 x 50 ml = 26.5 ppm
50/50,000 (50 l) = .001
26.5 x .001 = .0265 ppm Mo in your 50 liters of watering solution

MikeInOz recommends .05 ppm with fertilizers that are mostly nitrate N (what I have to do since my General Hydroponics 5-0-1 and ammonium sulfate combination is 2/3 nitrate N). However, since your fert and supplements give you a pretty much even split between ammonium N-urea N and nitrate N, .027 ppm Mo per feeding is right for your cacti and succulents.

I'm kinda thinking that a 1-liter bottle of stock solution won't last you for more than about 6 or 7 weeks. If that's the case, get a 5-liter jug for your stock solution. Dilution stays the same -- 1 gram per liter. Good news is that a little bit of Mo goes along way, so you won't have to "break the bank" when you purchase more ammonium molybdate.

[Wiandry Adi]

Hi Steve,

thanks for the calculation! I'll try to get the ammonium molybdate ASAP and get 'em going. Knowing how minuscule the molybdenum scale shall be, this is going to be a challenge. Let's see how it goes!

Also, nice touch on Tokopedia right there! I don't know about Amazon since I never use it (only for looking products sold/available abroad), but it is a decent online market. I don't like its 'free shipping' (bebas ongkir) feature; I'd rather pay for the shipping for better courier services Does Amazon have that too?

[Steve Johnson]

Hi Adi,

I make about 99% of my nonfood purchases from Amazon, and I signed up for Amazon Prime, so free shipping on everything. Even better -- I get most of my stuff the next day (deliveries 7 days a week).

While you're waiting for the ammonium molybdate, I just wanted to explain what Mo does:

• Molybdenum is an essential component in two enzymes that convert nitrate into nitrite (a toxic form of nitrogen) and then into ammonia before it is used to synthesize amino acids within the plant. Plants also use Mo to convert inorganic phosphorus into organic forms in the plant.

A little more detail from Nutrient Tech:

Molybdenum02.jpg (56.58 KiB) Viewed 126671 times

Although what you just saw is geared toward crop production, you'll understand how and why Mo has an important role in cactus and succulent growth too. Before I learned about this, I didn't realize that nitrate (and almost 0 Mo) from the Dyna-Gro 7-7-7 I had been using since 2012 was slowly building up in the tissues of my cacti. Maybe not at toxic levels, but I'm sure it led to problems I wouldn't be aware of (or at least not obvious enough to notice). With Mo added to my new fertilizer regimen this year, I'm also sure that it's one of the reasons why I've seen substantial improvements. Your plants will get the benefits of Mo in your watering solution, and as I said earlier, a little bit goes a long way.