CactiGuide.com

https://www.rrm.me.uk/Cacti/Cactus%20an ... linity.pdf

https://www.cactusnursery.co.uk/ph.htm

Thank you Steve Johnson I am not arguing , I just find these articles interesting. They seems to disagree a bit about the alcalinity question. Our water is very soft, don’t remember exactly the readings but soap foams very well and calcium build up on different things isn’t a problem.

Hallo Mrs. Green,
you've got really lovely Astros there (I am a fan, too) & I am really happy that so many survived. Those are really nice flowers, too. So you did everything right, didn't you?

I admit I was very suspicious when I read about your soil:

Fully-coated, premium-quality fertilizer. The coating is purely organize and breaks down without leaving any residue. The fertilizer supplies your plant with nutrients for up to 6 months.

How could one ever get that stuff washed out...?! But obviously the mix was fine for your plants?
Would you write, where you live, that it is so hard to get pure pumice?

Keeping fingers crossed for your Astros,
N.

Mrs. Green, I may have to walk back something I said to you last month:

Steve Johnson wrote: ↑Sun Jul 16, 2023 9:25 pmThe fact that your spring water is pH-neutral only tells us that it doesn't contain any calcium bicarbonate (bicarbonate = temporary hardness). Permanent hardness (indicated by minerals in your spring water) could be a problem for your cacti over time. Unfortunately acidifying the water does nothing to neutralize permanent hardness, so the concern is having minerals building up in your mix. The best way to avoid that problem -- flush your pots with distilled water once a year while your cacti are in the growing season.

The learning never stops -- I made a rather interesting discovery last weekend:

• From LibreTexts Chemistry:
  "Hard water is water containing high amounts of mineral ions. The most common ions found in hard water are the metal cations calcium (Ca2+) and magnesium (Mg2+), though iron, aluminum, and manganese may also be found in certain areas. These metals are water soluble, meaning they will dissolve in water. " [My emphasis] By the way, people get confused about the difference between hardness and alkalinity. Now we know -- alkalinity = temporary hardness = Calcium bicarbonate in water. Good news that you don't have a bicarbonate problem.

I've always thought that hard water is bad for cacti (or at least desert cacti), but now I wonder if it's one of those myths people keep falling for. If your spring water contains calcium and magnesium cations, your desert cacti will be able to use Ca and Mg right from the source. If you're not sure about whether it does or not, you might want to take a sample to a test lab.

I still recommend that you flush your pots with distilled water once a year while your cacti are in the growing season because fertilizer salts building up in the mix could be a problem over time.

Steve, Temporary hardness would be from Sodium or Potassium bicarbonate. That is also known as Alkalinity. If you have a solution of Calcium bicarbonate you will have both Alkalinity and Hardness. Alkalinity from bicarbonates, Hardness from Calcium. Carbon dioxide dissolving in water will produce Alkalinity in perfectly pure water very rapidly. It will be slight, but it will be measurable. Nothing we'd worry about.

For Mrs. Green: if you want to check your water hardness and alkalinity easily and cheaper than a lab, go to a store selling tropical fish. Test kits are available for lots of water parameters. You can even buy them online. Tetra is one brand.

Tetra- look for GH test kits for total calcium and magnesium values. Look for KH for carbonate hardness or alkalinity. https://www.tetra.net/en-eu/products/nu ... c065f56fff

nachtkrabb wrote: ↑Mon Aug 14, 2023 9:37 pm Hallo Mrs. Green,
you've got really lovely Astros there (I am a fan, too) & I am really happy that so many survived. Those are really nice flowers, too. So you did everything right, didn't you?

I admit I was very suspicious when I read about your soil:

Fully-coated, premium-quality fertilizer. The coating is purely organize and breaks down without leaving any residue. The fertilizer supplies your plant with nutrients for up to 6 months.

How could one ever get that stuff washed out...?! But obviously the mix was fine for your plants?
Would you write, where you live, that it is so hard to get pure pumice?

Keeping fingers crossed for your Astros,
N.

Hi Nachtcrab Thank you,the myriostigmas seems to thrive in the mentioned substrate. A fourth flower opened and there are more buds, that hopefully will open, if the weather gets nice enough this summer/fall.

I live in Norway and so far haven’t been able to find pumice locally, even when asking for it . I have found a few vendors online but the price wasn’t to my liking and when adding the freight cost..no, no.

jerrytheplater wrote: ↑Tue Aug 15, 2023 6:53 pm Carbon dioxide dissolving in water will produce Alkalinity in perfectly pure water very rapidly.

Afraid you have that backwards, Jerry - CO2 reacts with water to produce carbonic acid, which makes rainwater weakly acidic.

Mrs.Green wrote: ↑Wed Aug 16, 2023 7:59 am
I live in Norway and so far haven’t been able to find pumice locally, even when asking for it . I have found a few vendors online but the price wasn’t to my liking and when adding the freight cost..no, no.

Seems odd - shipping from Iceland should not be all that expensive.

Mrs.Green wrote: ↑Wed Aug 16, 2023 7:59 am

nachtkrabb wrote: ↑Mon Aug 14, 2023 9:37 pm Hallo Mrs. Green,
you've got really lovely Astros there (I am a fan, too) & I am really happy that so many survived. Those are really nice flowers, too. So you did everything right, didn't you?

I admit I was very suspicious when I read about your soil:

Fully-coated, premium-quality fertilizer. The coating is purely organize and breaks down without leaving any residue. The fertilizer supplies your plant with nutrients for up to 6 months.

How could one ever get that stuff washed out...?! But obviously the mix was fine for your plants?
Would you write, where you live, that it is so hard to get pure pumice?

Keeping fingers crossed for your Astros,
N.

Hi Nachtcrab Thank you,the myriostigmas seems to thrive in the mentioned substrate. A fourth flower opened and there are more buds, that hopefully will open, if the weather gets nice enough this summer/fall.

I live in Norway and so far haven’t been able to find pumice locally, even when asking for it . I have found a few vendors online but the price wasn’t to my liking and when adding the freight cost..no, no.

Mats Winberg who operates the seed retail website (SuccSeed) lives in Sweden, and grows not only Astrophytum, but many other plants from warm climates, He produces many flowers (his photos prove that), and he also produces a good percentage of the seed he sells himself.

If you live near a volcanic region, pumice and other similar minerals typically are near by. So there is likely someone profiting from them, and you should be able to acquire such materials from them or their distributors. Good luck, and good growing!

Tom in Tucson wrote: ↑Wed Aug 16, 2023 7:07 pm Mats Winberg who operates the seed retail website (SuccSeed) lives in Sweden, and grows not only Astrophytum, but many other plants from warm climates, He produces many flowers (his photos prove that), and he also produces a good percentage of the seed he sells himself. (...)

Yes, on https://www.succseed.com/ they have real nice pictures. But they offer no pumice or any other kind of soil.
N.

greenknight wrote: ↑Wed Aug 16, 2023 8:52 am

jerrytheplater wrote: ↑Tue Aug 15, 2023 6:53 pm Carbon dioxide dissolving in water will produce Alkalinity in perfectly pure water very rapidly.

Afraid you have that backwards, Jerry - CO2 reacts with water to produce carbonic acid, which makes rainwater weakly acidic.

Spence, I did say the Alkalinity would be slight and was thinking of the Alkalinity tests I've done that have an endpoint of pH 4.5 for Total Alkalinity like in this procedure: https://www.cefns.nau.edu/~teb/ambl/sop ... linity.pdf

I found this site: https://www.globalseafood.org/advocate/ ... uaculture/

...Which explains how CO2 forms acid in water, yet it can raise alkalinity in water. The explanation is a little confusing, but if I understand it correctly it's because the CO2 increases the solubility of calcium-containing minerals.

The link is discussing the effects of rising atmospheric CO2 levels on both fresh and salt water aquaculture. Very interesting reading.

The article discusses fresh water containing Alkalinity from dissolved limestone (calcium carbonate) and other minerals including silicates. It gives the equilibrium chemical equation for the dissolution of limestone by CO2 dissolving in water to give Calcium and Bicarbonate.

CaCO3 + CO2 + H2O ⇌ Ca2+ + 2HCO3- .

⇌ is the symbol for an equilibrium condition, that the equation can go both ways-left or right. So, when CO2 from the air dissolves in the water on the left side, it forms carbonic acid which lowers the pH and dissolves more limestone. That means the bicarbonate, HCO3- increases on the right along with the calcium. The bicarbonate is what increases the Alkalinity.

But, originally I said "Carbon dioxide dissolving in water will produce Alkalinity in perfectly pure water very rapidly. It will be slight, but it will be measurable. Nothing we'd worry about." I was talking about absolutely pure water with nothing in it at all, no alkalinity, pH 7.0, no CO2, no silicates. That is very hard to get and I'm not even sure if it really can be gotten. Labs can produce what is known at 18 meg ohm water and that is very pure.

So, what I was saying is that if carbon dioxide dissolves in pure water it will produce Alkalinity. It will first produce carbonic acid like this:

CO2 + H2O ⇌ H2CO3

Then the carbonic acid will dissociate into bicarbonate and hydrogen ions like this:

H2CO3 ⇌ HCO3- + H+

The pH will drop to maybe 5.5 and you will now have water that contains:

H2O + CO2 + H2CO3 + HCO3- + H+ all together at equilibrium. The bicarbonate will produce a measurable Alkalinity in the now no longer pure water over time as it absorbs atmospheric carbon dioxide.

Want a low tech video to explain? This one is from an aquarium explanation: https://youtu.be/pvfZUFI9lDw

jerrytheplater wrote: ↑Tue Aug 15, 2023 6:53 pm Steve, Temporary hardness would be from Sodium or Potassium bicarbonate. That is also known as Alkalinity. If you have a solution of Calcium bicarbonate you will have both Alkalinity and Hardness. Alkalinity from bicarbonates, Hardness from Calcium. Carbon dioxide dissolving in water will produce Alkalinity in perfectly pure water very rapidly. It will be slight, but it will be measurable. Nothing we'd worry about.

Got it -- thanks, Jerry!

Thanks to everyone replying in this thread I do find it interesting to read but I have to confess I like to do things as simple as possible. (as long as it works for me) I know myself and I know that having to pick up a calculator everytime I use ferts on my plants.. maybe the first two times ( at best) but after that nah..

I belive there is more than one way to Rome, what works wonders for grower A and D, may not give the same results for growers B and C and vice versa. Only natural, since these growers may be growing their plants under very different conditions.

For me, a combination on learning from other peoples experience and not at least from my own plants/ experience is what is interesting .I also find it intersting that people that seemingly have no ‘serious’ interest in cacti, have success with the plants they grow. They just have years of experience with growing plants and ‘fingerspitzgefühl’.
I am again thinking of the old lady I visited. She really has green thumbs , both outside and inside is filled with plants and among these cacti. She didn’t knew the name of any of the cacti, grew them in ordinary potting soil but they really looked good and flowered too.

Do I think that special substrate and ferts adjusted to cacti is a waste? No,not at all. But I am pretty sure that there are no simple answers to the ‘right’ substrate/ferts/watering.

Hi Mrs.Green,
I admit to agree with you. I have met a person who had no idea that what he grew in one pot were a fern plus a cactus. Both thrieved. The cactus flowered each year. Well.

This convinced me that it is not only the plant, but also the planter, who make a difference, as well as the whole of the umwelt: Climate, other plants in the surrounding or even the same pot, air & air flow, light & shadow, temperatures over the year, pot & soil, kind & portions of water, fertilizers, etc.etc.etc. Always the combination & the interplay are important -- not to mention the "plant personality":
I have two Astrophytum ornatum. The one wants to spend its summer in full sun on the South balcony. The other prefers a shady place below the Cycas' leaves on the Western balcony. Well...?

So I am growing my plants unscientifically. If I look at the growth & the flowers, it might be a well enough approach for them. They look as happy as I feel.
N.

nachtkrabb wrote: ↑Sat Sep 16, 2023 1:35 pm Hi Mrs.Green,
I admit to agree with you. I have met a person who had no idea that what he grew in one pot were a fern plus a cactus. Both thrieved. The cactus flowered each year. Well.

This convinced me that it is not only the plant, but also the planter, who make a difference, as well as the whole of the umwelt: Climate, other plants in the surrounding or even the same pot, air & air flow, light & shadow, temperatures over the year, pot & soil, kind & portions of water, fertilizers, etc.etc.etc. Always the combination & the interplay are important -- not to mention the "plant personality":
I have two Astrophytum ornatum. The one wants to spend its summer in full sun on the South balcony. The other prefers a shady place below the Cycas' leaves on the Western balcony. Well...?

So I am growing my plants unscientifically. If I look at the growth & the flowers, it might be a well enough approach for them. They look as happy as I feel.
N.

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