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

[jerrytheplater]

• Turns out the rainwater I collected yesterday was a result of artificial rain, cloud-seeded with calcium chloride. Shall I use dechlorinator on this one, since there's chloride?

Wow!! You have clouds seeded to produce rain? Very bad in my opinion. Is your government doing this? Why?

On to your question about the chloride. Chloride is vastly different from "Chlorine" (Hypochlorite) (I'm sure you are not referring to Chlorine gas.) Chloride is what results when a salt like Calcium Chloride, Potassium Chloride, or Sodium Chloride dissolves in water. The compound breaks apart into its two ions like Ca+ and Cl-, or K+ and Cl-, or Na+ and Cl-.

"Chlorine" or Hypochlorite is what is added to drinking water to purify it from bacterial contamination as well as other living contaminants. It is an oxidizer. Sometimes it is added as pure Chlorine gas dissolved into the water. Sometimes it is added as Bleach Sodium Hypochlorite. Sometimes it is combined with ammonia to form Chloramine in the water. This is what Tropical fish dechlorinator reacts with. A simple one is Sodium Thiosulfate. It combines with the Hypochlorite to form NaCl and water. Here is the balanced chemical equation for it:

4 NaClO (Sodium Hypochlorite) + Na2S2O3 (Sodium Thiosulfate) + 2 NaOH (Sodium Hydroxide) → 4 NaCl (Sodium Chloride)+ 2 Na2SO4 (Sodium Sulfate) + H2O (water)

[Steve Johnson]

The digital scale and pH meter are on the way, as well as the PROVIT Orange and Pak Tani 16-16-16 (often mistaken as Mutiara 16-16-16; my bad on that part).

Excellent! However, you do have 2 more items for your shopping list:

My teaspoon measured at 5 cm x 3.5 cm and 1 cm deep.

That's 17.5 cubic centimeters -- 3.5 metric teaspoons. Unfortunately too much for what you need, so buy 1 tsp. and 1/2 tsp. measuring spoons if you don't already have them. Please verify whether your teaspoons are in metric or US measures. Why the half-teaspoon? I'm thinking that 1.5 tsp. might be better than 2 tsp. for each fertilizer. All you need to do is weigh 1 tsp. per fert and give me their weights in grams. Once I run the ppm calculations, I'll let you know if you should dilute 1.5 or 2 tsp. each fert per 50-liter bucket of water. Absolute precision isn't required, although I'd like to get you as close as possible for what your cacti should be receiving nutrient-wise.

Turns out the rainwater I collected yesterday was a result of artificial rain, cloud-seeded with calcium chloride. Shall I use dechlorinator on this one, since there's chloride?

This is from Jerry's post:

Chloride is vastly different from "Chlorine" (Hypochlorite) (I'm sure you are not referring to Chlorine gas.) Chloride is what results when a salt like Calcium Chloride, Potassium Chloride, or Sodium Chloride dissolves in water. The compound breaks apart into its two ions like Ca+ and Cl-, or K+ and Cl-, or Na+ and Cl-.

"Chlorine" or Hypochlorite is what is added to drinking water to purify it from bacterial contamination as well as other living contaminants. It is an oxidizer. Sometimes it is added as pure Chlorine gas dissolved into the water. Sometimes it is added as Bleach Sodium Hypochlorite. Sometimes it is combined with ammonia to form Chloramine in the water. This is what Tropical fish dechlorinator reacts with.

You can't dechlorinate cloud-seeded rainwater, and IMO any chloride salt in the water is bad for potted plants. Cloud-seeding has been done for many years, although I share Jerry's objection to doing it. The fact that your government is doing it too makes a good argument in favor of acidifying your tap water. Which brings me to my last point for the moment...

Calcium carbonate buildup in the pot takes a long time to negatively impact the roots. I don't think you'll have a problem if you water your cacti with tap water for a month or two, but of course it would be nice if you don't let it go that long. When I get the results of your water pH tests and give you the correct dilution amount for your fertilizers, step 5 will be to have you dilute the ferts in a 50-liter bucket of tap water, then test its pH and give me the number. No need for you to wait on step 6 -- water your cacti and get their nutrients going in the roots. While you do that, I'll calculate the correct amount of citric acid you'll need for acidification. The goal of step 6 is to make sure that your water-saturated mix starts out with a pH no lower than 6.0. This nutrient availability chart will come into play:

pH_nutrient_ availability_ chart01.jpg (81.4 KiB) Viewed 291699 times

As alkalinity is neutralized while water in the mix dries out, pH will rebound up. If the mix dries out completely with an end pH of 7.0, neutralization is complete. But even if the end pH is more like 7.5 (and this kinda surprised me when I saw the chart for the first time), N, P, K, Ca, Mg, and S are still readily available to the plant. While you won't know what the end pH is, I can tell you from experience that it'll be fine.

...I saw ascorbic acid/vitamin C can be used to acidify water too in some sources...

That'll work -- all the "ates" (acetate, citrate, ascorbate) make water-soluble calcium available to the plant. If you go with ascorbic acid/vitamin C, be sure to buy a product specifically for plants, not humans. (Vitamin C products for humans might contain additional stuff your cacti won't want.)

Update: What I just said may not necessarily be true -- check this out on Amazon:

https://www.amazon.com/Its-Just-Vitamin ... 211&sr=8-5

Adi, if you can buy a product just like that, you'll be set for acidification.

[Wiandry Adi]

The digital scale and pH meter are on the way, as well as the PROVIT Orange and Pak Tani 16-16-16 (often mistaken as Mutiara 16-16-16; my bad on that part).

Excellent! However, you do have 2 more items for your shopping list:

My teaspoon measured at 5 cm x 3.5 cm and 1 cm deep.

That's 17.5 cubic centimeters -- 3.5 metric teaspoons. Unfortunately too much for what you need, so buy 1 tsp. and 1/2 tsp. measuring spoons if you don't already have them. Please verify whether your teaspoons are in metric or US measures. Why the half-teaspoon? I'm thinking that 1.5 tsp. might be better than 2 tsp. for each fertilizer. All you need to do is weigh 1 tsp. per fert and give me their weights in grams. Once I run the ppm calculations, I'll let you know if you should dilute 1.5 or 2 tsp. each fert per 50-liter bucket of water. Absolute precision isn't required, although I'd like to get you as close as possible for what your cacti should be receiving nutrient-wise.

Turns out the rainwater I collected yesterday was a result of artificial rain, cloud-seeded with calcium chloride. Shall I use dechlorinator on this one, since there's chloride?

This is from Jerry's post:

Chloride is vastly different from "Chlorine" (Hypochlorite) (I'm sure you are not referring to Chlorine gas.) Chloride is what results when a salt like Calcium Chloride, Potassium Chloride, or Sodium Chloride dissolves in water. The compound breaks apart into its two ions like Ca+ and Cl-, or K+ and Cl-, or Na+ and Cl-.

"Chlorine" or Hypochlorite is what is added to drinking water to purify it from bacterial contamination as well as other living contaminants. It is an oxidizer. Sometimes it is added as pure Chlorine gas dissolved into the water. Sometimes it is added as Bleach Sodium Hypochlorite. Sometimes it is combined with ammonia to form Chloramine in the water. This is what Tropical fish dechlorinator reacts with.

You can't dechlorinate cloud-seeded rainwater, and IMO any chloride salt in the water is bad for potted plants. Cloud-seeding has been done for many years, although I share Jerry's objection to doing it. The fact that your government is doing it too makes a good argument in favor of acidifying your tap water. Which brings me to my last point for the moment...

Calcium carbonate buildup in the pot takes a long time to negatively impact the roots. I don't think you'll have a problem if you water your cacti with tap water for a month or two, but of course it would be nice if you don't let it go that long. When I get the results of your water pH tests and give you the correct dilution amount for your fertilizers, step 5 will be to have you dilute the ferts in a 50-liter bucket of tap water, then test its pH and give me the number. No need for you to wait on step 6 -- water your cacti and get their nutrients going in the roots. While you do that, I'll calculate the correct amount of citric acid you'll need for acidification. The goal of step 6 is to make sure that your water-saturated mix starts out with a pH no lower than 6.0. This nutrient availability chart will come into play:

pH_nutrient_ availability_ chart01.jpg

As alkalinity is neutralized while water in the mix dries out, pH will rebound up. If the mix dries out completely with an end pH of 7.0, neutralization is complete. But even if the end pH is more like 7.5 (and this kinda surprised me when I saw the chart for the first time), N, P, K, Ca, Mg, and S are still readily available to the plant. While you won't know what the end pH is, I can tell you from experience that it'll be fine.

...I saw ascorbic acid/vitamin C can be used to acidify water too in some sources...

That'll work -- all the "ates" (acetate, citrate, ascorbate) make water-soluble calcium available to the plant. If you go with ascorbic acid/vitamin C, be sure to buy a product specifically for plants, not humans. (Vitamin C products for humans might contain additional stuff your cacti won't want.)

Update: What I just said may not necessarily be true -- check this out on Amazon:

https://www.amazon.com/Its-Just-Vitamin ... 211&sr=8-5

Adi, if you can buy a product just like that, you'll be set for acidification.

I didn't know teaspoon sizes can vary like that! Or, until I got to know teaspoon can be both a utensil (which we use to stir our teas and other condiments) and measurement (which might bring hot topics here). Well, teaspoons in my home quite vary in sizes; whatever spoon that isn't larger than a utensil-tablespoon is a 'teaspoon'. I really need to improve my vocabulary on this one

Alright then, a set of measuring spoon coming up!

In regards of step 5, that means I put the ferts first, then acidifying it (plus adding dechlorinator)? I don't know if this will bring another hot topic, but how about acidifying first + dechlorinator, then ferts? Also, I decided to stick with citric acid and my current pH-down; ascorbic acid is quite a financially challenging purchase. Perhaps it's suited better for human consumption, though I'll reconsider it once there are differences found between citric and ascorbic acid in terms of acidifying quality.

And also thanks for the knowledge about soil and nutrients! And while we're at it, I'll discuss about this artificial rain:

Wow!! You have clouds seeded to produce rain? Very bad in my opinion. Is your government doing this? Why?

On to your question about the chloride. Chloride is vastly different from "Chlorine" (Hypochlorite) (I'm sure you are not referring to Chlorine gas.) Chloride is what results when a salt like Calcium Chloride, Potassium Chloride, or Sodium Chloride dissolves in water. The compound breaks apart into its two ions like Ca+ and Cl-, or K+ and Cl-, or Na+ and Cl-.

"Chlorine" or Hypochlorite is what is added to drinking water to purify it from bacterial contamination as well as other living contaminants. It is an oxidizer. Sometimes it is added as pure Chlorine gas dissolved into the water. Sometimes it is added as Bleach Sodium Hypochlorite. Sometimes it is combined with ammonia to form Chloramine in the water. This is what Tropical fish dechlorinator reacts with. A simple one is Sodium Thiosulfate. It combines with the Hypochlorite to form NaCl and water. Here is the balanced chemical equation for it:

4 NaClO (Sodium Hypochlorite) + Na2S2O3 (Sodium Thiosulfate) + 2 NaOH (Sodium Hydroxide) → 4 NaCl (Sodium Chloride)+ 2 Na2SO4 (Sodium Sulfate) + H2O (water)

Jakarta has recorded a severe level of air pollution for about a month now since the drought began (I saw in some news headline that it became the worst air quality in the world at the time, perhaps until now too). Yes, this rain was initiated as a mean to purge the air pollution number in Jakarta and its neighboring region (Jabodetabek) as well as helping irrigating parks, gardens, and farms. I remembered back in August, there was another attempt to initiate artificial rain, but out of nowhere, they stated they use sodium chloride (NaCl) of all things considered.

And as expected, the rain was even barely a drizzle. But to think table salts in the rainwater, just imagine if it's actually pouring

Jerry, thank you for the follow-up. Now it seems that the rainwater I've collected is still in the waiting room, waiting for its final judgement. I mean, based on what Steve just posted, that rainwater can be used for something else, away from the garden.

[jerrytheplater]

Totally off topic Adi. Cactoponi added a new video with English subtitles and said it was just for me. Ha Ha. It was a great video on Madagascar Euphorbia.

[Steve Johnson]

I didn't know teaspoon sizes can vary like that! Or, until I got to know teaspoon can be both a utensil (which we use to stir our teas and other condiments) and measurement (which might bring hot topics here). Well, teaspoons in my home quite vary in sizes; whatever spoon that isn't larger than a utensil-tablespoon is a 'teaspoon'. I really need to improve my vocabulary on this one

Alright then, a set of measuring spoon coming up!

No worries -- a complete set of measuring spoons aren't just for the kitchen, and they'll come in handy for what you're doing. Only difference between here and the rest of world is that our measuring spoons are in Standard (US) measures, in every other country they're metric. If you don't already have measuring cups, get them in 1/4 cup, 1/2 cup, and 1 cup sizes. Unless you say otherwise, I'll assume they're metric cups too.

In regards of step 5, that means I put the ferts first, then acidifying it (plus adding dechlorinator)? I don't know if this will bring another hot topic, but how about acidifying first + dechlorinator, then ferts?

Nope. First of all, I've been watering my cacti with chlorinated tap water for 12 years, and this hasn't been causing any problems. Unless your tap water is highly chlorinated (as in it smells like you're next to a swimming pool), I don't think you'll need to add a dechlorinator. If you do, you'll need to find out if it changes your watering solution's final pH. Ditto on the fertilizers -- they tend to lower the pH a little bit, and there's a good reason why the correct amount of acidifier has to be determined through calculations in step 6.

Also, I decided to stick with citric acid and my current pH-down; ascorbic acid is quite a financially challenging purchase. Perhaps it's suited better for human consumption, though I'll reconsider it once there are differences found between citric and ascorbic acid in terms of acidifying quality.

Sorry, but that sends up a red flag -- from what I understand, pH-down is always phosphoric acid, and the last thing you need is more phosphorus upsetting the proper NPK balance established by the three ferts you'll use. If your pH-down isn't phosphoric acid, I'll need to know its chemical composition before you decide to continue using it. There's no qualitative difference between citric and ascorbic acids, so if citric acid is more affordable for you, go with it. The point is that citric acid is more concentrated than the acetic acid in 5% vinegar, and having to use large amounts of vinegar makes no economic sense given the large amount of water you use for your collection. Besides that, vinegar is stinky!

Jakarta has recorded a severe level of air pollution for about a month now since the drought began (I saw in some news headline that it became the worst air quality in the world at the time, perhaps until now too).

I'll send you a PM about that.

[Wiandry Adi]

Totally off topic Adi. Cactoponi added a new video with English subtitles and said it was just for me. Ha Ha. It was a great video on Madagascar Euphorbia.

Yeah, I saw it too. Great presentation from him as well! I kinda wish he's here in CactiGuide forum too but I think it'd ultimately be his decision

[Wiandry Adi]

I've conducted all the test required for this calculation and here are the results:

pH test



Fertilizer weight test (extra info attached on the images) [the weight of the cup has been subtracted; the weight scale's tare-weight feature works properly)





Also, I'm still on my way to fully finish refurbishing my garden, so please keep on the look for my garden updates! (it's still a little too messy for being presented) I think it shall be done next week, as unfortunately I have to go for a trip this Sunday so I can't attend my garden (I'll water my collections on Monday to Wednesday)

[Steve Johnson]

Hi Adi,

Your untreated tap water testing at a pH of 7.02 -- calcium bicarbonate in the water isn't worth speaking of, so that's good. My initial assessment is that if you need to acidify at all, it'll only be for the alkaline mix. I just got home from work about 20 minutes ago, so I'll do some "homework" on the calculations for your three fertilizers, numbers to follow -- if not tonight, then tomorrow. Step 6 will be easy:

• Dilute the ferts in a 50-liter bucket of tap water per the amounts I'll recommend for you. Give them a little bit of time to fully dissolve, test the pH of the water after dilution, and give me that number.

Ammonium N (NH4) in your ferts is an acidifier, and I believe the P2O5 is an acidifier too. If we get lucky, you won't need any additional acidification even for your alkaline mix. The pH results of step 6 will tell the story.

Before we continue, I have a couple of questions about your weights:

• Pak Tani 16-16-16 -- 1/2 metric teaspoon = 2.73 grams. 1 metric teaspoon should be 5.46 gr, but you weighed it at 4.87 gr.

• PROVIT ORANGE -- 1/2 metric teaspoon = 3.71 gr. I metric teaspoon should be 7.42 gr, but you weighed it at 5.93 gr.

• Mulitiara GROWER -- 1/2 metric teaspoon = 3.00 gr. 1 metric teaspoon should be 6.00 gr, but you weighed it at 5.00 gr.

Those are pretty big discrepancies, and I can see that you were weighing level teaspoons, so the discrepancies aren't coming from there. My questions are:

• Can your scale be calibrated? If so and it didn't come with a calibration weight, sorry, but that's something else you have to buy. The manufacturer's documentation will include the procedure for calibration. (My apologies for not bringing this up earlier.)

• Does your scale include a tare function? If so, place the empty plastic cup on the scale and set the tare to 0 before you measure each fertilizer again. Once again, the manufacturer's documentation will show you how to use the tare function.

Not the worst thing in the world if your scale can't be calibrated, and I kinda think that it wouldn't account for much of the discrepancy anyway. (Just want to cover my bases here.) If it doesn't have a tare function, measure the weight of the empty cup and subtract it from the weight of the ferts in the cup, then give me the amounts. Something doesn't seem to be adding up, and I don't want to give you inaccurate results when I calculate the N, P, and K ppm numbers in your watering solution, so best to have you double-check your weight measurements.

By the way, I vaguely remember that Pak Tani contains 5% Ca and 1% Mg. Is that correct? If so, they'll be a nice addition to the Ca and Mg in your tap water. As MikeInOz has said elsewhere on the forum, there's no such thing as too much calcium.

[Wiandry Adi]

Before we continue, I have a couple of questions about your weights:

• Pak Tani 16-16-16 -- 1/2 metric teaspoon = 2.73 grams. 1 metric teaspoon should be 5.46 gr, but you weighed it at 4.87 gr.

• PROVIT ORANGE -- 1/2 metric teaspoon = 3.71 gr. I metric teaspoon should be 7.42 gr, but you weighed it at 5.93 gr.

• Mulitiara GROWER -- 1/2 metric teaspoon = 3.00 gr. 1 metric teaspoon should be 6.00 gr, but you weighed it at 5.00 gr.

Those are pretty big discrepancies, and I can see that you were weighing level teaspoons, so the discrepancies aren't coming from there. My questions are:

• Can your scale be calibrated? If so and it didn't come with a calibration weight, sorry, but that's something else you have to buy. The manufacturer's documentation will include the procedure for calibration. (My apologies for not bringing this up earlier.)

• Does your scale include a tare function? If so, place the empty plastic cup on the scale and set the tare to 0 before you measure each fertilizer again. Once again, the manufacturer's documentation will show you how to use the tare function.

Not the worst thing in the world if your scale can't be calibrated, and I kinda think that it wouldn't account for much of the discrepancy anyway. (Just want to cover my bases here.) If it doesn't have a tare function, measure the weight of the empty cup and subtract it from the weight of the ferts in the cup, then give me the amounts. Something doesn't seem to be adding up, and I don't want to give you inaccurate results when I calculate the N, P, and K ppm numbers in your watering solution, so best to have you double-check your weight measurements.

By the way, I vaguely remember that Pak Tani contains 5% Ca and 1% Mg. Is that correct? If so, they'll be a nice addition to the Ca and Mg in your tap water. As MikeInOz has said elsewhere on the forum, there's no such thing as too much calcium.

Oh my, I didn't notice that (1/2 + 1/2 = 1, how come I overlooked this?). I have checked everything - I made sure the weight scale work properly so I don't place a complaint - and after several checking - measuring a small flashdisk, a scissor, and the plastic cup itself - it worked as expected, and it has tare function, as I have posted before:

(the weight of the cup has been subtracted; the weight scale's tare-weight feature works properly)

...though the fact a teaspoon measures differently is quite surprising. I didn't think this through so I'll try to either calibrate the scale (it has instruction for it) and then re-scale, or re-scale with 1/2 teaspoon twice. Perhaps I'll do both to get more certain results.

As I've posted before, I'll be having a tour tomorrow so I can't attend my garden nor continue this project. I'll continue on Monday.

By the way, I vaguely remember that Pak Tani contains 5% Ca and 1% Mg. Is that correct? If so, they'll be a nice addition to the Ca and Mg in your tap water. As MikeInOz has said elsewhere on the forum, there's no such thing as too much calcium.

Yes, one of the reasons why I get Pak Tani 16-16-16 thanks to 4:1 cal-mag ratio. Although I'm curious on by 'no such thing as too much calcium', is it that we can over-apply calcium ferts and go away with it or calcium build-up in the soil for extended periods of time is not of serious concern?

[Steve Johnson]

I've been in the precision measuring business for a lot of years, and I can't tell you how many times I was calibrating a measuring system when I would go "well, that just isn't right". Turns out that 99% time it was little old me engaging in "operator error". Oops! That's why it's always good to double-check.

Although I'm curious on by 'no such thing as too much calcium', is it that we can over-apply calcium ferts and go away with it or calcium build-up in the soil for extended periods of time is not of serious concern?

It's not so much about "getting away with it", but making sure that cacti are getting calcium in forms that are available to them. Calcium carbonate buildup from evaporated bicarbonate is a problem because it's insoluble (the reason why alkalinity needs to be neutralized one way or another). Cactus species native to growing in limestone desert soils are able to use calcium from limestone in the mix, but it inhibits growth in species that aren't. Generally speaking, gypsum makes calcium available to pretty much all species including epiphytes. The same applies to the Ca and Mg cations in hard water as well as the Ca and Mg sources coming from fertilizers. The concern I had was the possibility that calcium might build up to toxic levels in the plant's tissues, but Mike also stated that there's no such thing as Ca toxicity. Do cacti take as much as they need and leave the rest behind in the pot? I suppose that's possible, and we already know the solution to the problem in case one exists -- flush the pots with pure water and nothing more once a year.

[Wiandry Adi]

Quick update:

OK, I got quite a lot of break time so I have calibrated my scale - and even use a spare weight scale that I bought by accident - and re-scale everything and here's the weird thing I've found:

• Even after calibration, 1/2 and 1 teaspoon scaling still gave the same result (my bad for not documenting this one)

• When I scale with 1/2 teaspoon twice, it's what we have been expected, as in 3.00 grams in 2 1/2 teaspoons will give me 6.00 grams, but not 1 teaspoon.

• Not all 'level' teaspoon give exact measurement like my previous result, therefore I rely on rounding the final scale results.

I hope you get what I mean, because I can't really show things in real-time or getting it on video.

Though, there is something you can consider, Steve:

• The 1/2 teaspoon measures at 2.5 x 2.5 x 1 cm

• The 1 teaspoon measures at 3 x 3 x 1.5 cm

• I don't know but you may compare this size to US teaspoon and there may be some plot twists.

I don 't know if that helps, but this may be the answer for this calamity.

[Steve Johnson]

I don 't know if that helps, but this may be the answer for this calamity.

No, not a calamity -- just a challenge. More volume = more air spaces among the granules, so that may explain why 1 metric teaspoon weighs less than we would expect at least with the Pak Tani and Multiara GROWER. However, PROVIT ORANGE is a powder, so it should be closer to a weight of 7.42 grams. Only 5.93 grams -- that I can't explain. Given the fact that you'll be fertilizing pretty much every time you water, would it be a hassle if you dilute by weight instead of volume? If you don't mind using the scale whenever you make your 50-liter buckets of watering solution, the amount of nutrients going to your cacti will be more consistent with each feeding. If you'd rather dilute by volume, the best I can give you is an approximation calculating the weights of your ferts by metric teaspoon.

[jerrytheplater]

It is not unheard of for Kitchen measuring spoons to be inaccurate. Try weighing distilled water in each spoon. Try to match the height of the meniscus each time you measure. This will tell you better if the volume of the spoons is correct. You have to be careful you don't spill before you weigh. Also, some water will remain in the spoon due to surface tension. Try adding a drop or two of dish soap to your water to reduce the surface tension. Don't make bubbles.

And, it is best to take multiple measurements (8-10) and take an average of them to get a weight for the volume. Too many variables: settling of the granules in the spoon changing the packing density; different filling heights as in inconsistent leveling; Different granule sizes in each measurement... This is why weight is preferred over volume.

[Steve Johnson]

It is not unheard of for Kitchen measuring spoons to be inaccurate. Try weighing distilled water in each spoon. Try to match the height of the meniscus each time you measure.

Adi, in case you're not familiar with the term (I wasn't until just now), read this:

https://www.thoughtco.com/how-to-read-a-meniscus-606055

Jerry is correct -- measuring spoons sold for home use aren't calibrated, and they're not supposed to be. But you can if you follow his instructions. The calibration standard is easy -- 1 metric teaspoon of water = 5 cubic centimeters = 5 grams. And since the calibration constant is water, whatever deviations you get will give you the exact volume of your 1/2 and 1-teaspoon measuring spoons.

For dry fertilizers that are water-soluble, dilution is a trade-off between accuracy and convenience. If you prefer accuracy, diluting your ferts by weight will obviously be the best way to go. If you need to go with convenience diluting your ferts by volume, expect some inconsistency regarding nutrient dosages going to your cacti per feeding. Would that inconsistency be a significant problem? It's something I'd have to test. When you're back on the forum next week, we'll figure out what to do as the adventure continues. (Maybe I'm weird, but this is fun! )

[Wiandry Adi]

It seems we've entered another hot topic to the point this thread might scorch this reminds me back in my college days when I presented my assignments to my lecturers, they'd add more to the conversation and we had heated arguments on how it should be done, but ultimately we reached the same conclusion. Thought I'd be finished early, but turned out there were still more revisions to come.

Fertilizing by weight, for me, seems to be the ideal option since it provides accuracy and therefore better nutrient uptake. However, it means for every ferts I'm about to apply, I have to measure them. Seems inconvenient, but knowing it's the better option, I'll give it a shot, like when I fertilize during the weekends.

Fertilizing by volume is the more realistic option: it's more time-convenient and uses less gizmos. Of course this won't be a good thing in the long run since accidental overfertilizing can happen, like if I accidentally put a little too much while I thought it's still the same volume. That's why if I have to fertilize by volume, I'll try my best to measure below the numbers we've agreed upon.

And with more busy days coming, fertilizing by volume will unfortunately be the only viable option, though if I can get a day to fertilize in the weekend, I'll go by weight.

Here's my proposed volume - measured by the metric 1/2 teaspoon (judging by Mutiara GROWER's result, it should be around 3 grams - my safe bet):

• Pak Tani 16-16-16 : a teaspoon

• PROVIT Orange: half a teaspoon

• Mutiara GROWER: a teaspoon

Again, if I have time to use weight, I'll definitely use it.

I'll get the sample of my tap water's pH which has been treated by dechlorinator - no pH-down - and added with those three ferts with the listed volume tomorrow, although before I start, I can wait for suggestions in regards of the ferts' volume