To flush LECA medium with tap water or reverse osmosis water?

[Ray]

Aw, c'mon now, OW. Now you're getting pickier than me!

I suspect that a lot of this is due to English not being the author's primary language, but in that questionable "dictionary", they state that "permanent hardness is caused by the presence chlorides, nitrates and sulphates of calcium and magnesium, which will not be precipitated by boiling", while every other water quality text I've ever seen says that it is calcium-, magnesium-, and iron carbonates. They go on to contradict that with their "lime scale" comments in the same paragraph.

They also describe that boiling does not get rid of temporary hardness; it changes it into permanent hardness!

[OrchideeNormus]

This is interesting to see this debate because the information I've been finding regarding this subject can be contradicting. Just like this conversation lol.
I suppose the important part for me to understand is that my water is definitely not good for orchids. Any other house plant or cacti I have has never had an issue, but I noticed a salt build up right away on the roots when I got my first orchid. After my initial research I did try boiling the water and allowing it to sit for 24 hours before using it, I even tried adding the water treatment for my fish tank to it lol. Now that I've got this TDS meter... I'm just trying to figure out what all that mean now lol. As far as complaining about the water company, as I mentioned before, it's been done before and failed. The people who run it have the monopoly on it somehow in this community and seem to have friends in high places. The ones who have already gone up against them have more pull than I do in this community. If they couldn't do anything about it, I highly doubt there's much I can do that will have a different outcome. I will see if I can't get that report today, they are already 20 minutes late so we shall see if they even show up today. For now the best I can do is be conscious of what I have learned and apply that knowledge to my life ♡

[estación seca]

Are you on the reservation?

[OrchideeNormus]

Originally Posted by estación seca

Are you on the reservation?

No I'm not

[Orchid Whisperer]

Originally Posted by Ray

Aw, c'mon now, OW. Now you're getting pickier than me!

I suspect that a lot of this is due to English not being the author's primary language, but in that questionable "dictionary", they state that "permanent hardness is caused by the presence chlorides, nitrates and sulphates of calcium and magnesium, which will not be precipitated by boiling", while every other water quality text I've ever seen says that it is calcium-, magnesium-, and iron carbonates. They go on to contradict that with their "lime scale" comments in the same paragraph.

They also describe that boiling does not get rid of temporary hardness; it changes it into permanent hardness!

Ray, that just happened to be the first description of permanent vs temporary hardness I came across at zero-dark-thirty in the morning while getting ready for my morning commute.

The concept is well known. So-called "temporary hardness" is associated with precipitation and scale formation, which can be induced by boiling, the remaining water will have lower hardness. It is associated with Ca and Mg bicarbonate (the Wikipedia page on hard water describes the chemistry in general terms, and also describes the difference from permanent hardness). My point is the OP was correct in saying some hardness can be removed by boiling; it depends on what minerals are dissolved that contribute to the hardness.

[Ray]

Originally Posted by Orchid Whisperer

Ray, that just happened to be the first description of permanent vs temporary hardness I came across at zero-dark-thirty in the morning while getting ready for my morning commute.

The concept is well known. So-called "temporary hardness" is associated with precipitation and scale formation, which can be induced by boiling, the remaining water will have lower hardness. It is associated with Ca and Mg bicarbonate (the Wikipedia page on hard water describes the chemistry in general terms, and also describes the difference from permanent hardness). My point is the OP was correct in saying some hardness can be removed by boiling; it depends on what minerals are dissolved that contribute to the hardness.

The problem with that is that in order for the dissolved solids to precipitate - the scale to deposit, if you will - the water must evaporate, which concentrates the solute, not dilutes it.

Maybe, based upon my experience, I'm just missing something, or maybe it's just a "terminology in the subject area" that's different.

[Orchid Whisperer]

Yep, you're missing something.
(Still using the Chemcraft chemistry sets at Georgia Tech? )

The heat drives a bicarbonate / carbonate reaction.

This website provides a good explanation, authored by chemists: Water Hardness

[estación seca]

Back to advising OrchideeNormus.

With high-mineral water, your growing method results in more minerals concentrating at the medium surface, due to evaporation, than you would have with pour-through watering. I would use R/O water most of the time for self-watering pots. Once minerals form on the surface (efflorescence), they won't dissolve back into the water to any practical degree, so this would not be removed by periodic flushing with pure water.

You can mix RO with well water to decrease the mineral concentration, but it helps to know exactly what you're starting with. See how much it would cost you to have a water quality analysis done on your tap water. It's for your safety, as well. Find out concentrations of total dissolved solids, nitrates, sodium, phosphate, boron and metals. Find the hardness.

Your water company might have their annual water quality report online. I think in the US they are required to provide it, though it is true some small rural water providers don't always do the best job.

[OrchideeNormus]

Originally Posted by estación seca

Back to advising OrchideeNormus.

With high-mineral water, your growing method results in more minerals concentrating at the medium surface, due to evaporation, than you would have with pour-through watering. I would use R/O water most of the time for self-watering pots. Once minerals form on the surface (efflorescence), they won't dissolve back into the water to any practical degree, so this would not be removed by periodic flushing with pure water.

You can mix RO with well water to decrease the mineral concentration, but it helps to know exactly what you're starting with. See how much it would cost you to have a water quality analysis done on your tap water. It's for your safety, as well. Find out concentrations of total dissolved solids, nitrates, sodium, phosphate, boron and metals. Find the hardness.

Your water company might have their annual water quality report online. I think in the US they are required to provide it, though it is true some small rural water providers don't always do the best job.

Are you saying flushing the pots isn't making any difference at all? I exclusively use RO water for watering and feeding. If flushing isn't going to make a difference I would rather not. It seems to be a popular habit and according to some deemed necessary. I have read several articles stating that the efflorescence won't hurt the plants so long as it's only on the medium and not on the roots. Only one of my phals is having issues with salt build up on the roots and I think I've figured that issue out (my ph was way too high for them to be absorbing anything). I was trying to be safe rather than sorry! If it's not necessary then tell me now and I won't waste my money anymore lol.

[Ray]

Originally Posted by Orchid Whisperer

Yep, you're missing something.
(Still using the Chemcraft chemistry sets at Georgia Tech? )

The heat drives a bicarbonate / carbonate reaction.

This website provides a good explanation, authored by chemists: Water Hardness

Hah! It has only been about 50 years, so what the hell.... Besides, merely boiling temperatures rarely played a role in my education. Start talking in the 2000°C area, and I'm far more comfortable.

From reading horticultural info, I was under the impression that bicarbonates expressed alkalinity, and as that article states, it's the carbonates that constitute hardness.

That Washington U article was good. Thanks for digging it up.

---------- Post added at 03:41 PM ---------- Previous post was at 03:27 PM ----------

Originally Posted by OrchideeNormus

Are you saying flushing the pots isn't making any difference at all? I exclusively use RO water for watering and feeding. If flushing isn't going to make a difference I would rather not. It seems to be a popular habit and according to some deemed necessary. I have read several articles stating that the efflorescence won't hurt the plants so long as it's only on the medium and not on the roots. Only one of my phals is having issues with salt build up on the roots and I think I've figured that issue out (my ph was way too high for them to be absorbing anything). I was trying to be safe rather than sorry! If it's not necessary then tell me now and I won't waste my money anymore lol.

If you use RO for watering and feeding, then use your hard water for flushing, you're defeating the purpose of flushing, to some degree.

If you don't want to flush (I've not done a separate flushing in 20 years), consider following my approach:

• feed low-concentration fertilizer solution at every watering ("low concentration" will be defined by your watering frequency)
• always fill the pot rapidly to the top and let it drain, accomplishing feeding, watering, and flushing at once. If you still want to do a periodic plain water flush, use the RO.

Precipitates on the medium can, indeed, poison the plant. When they get wet, some of those solids redissolve, raising the solution concentration in the medium. The more extensive the buildup, the worse it is, and, if a newly-emerging root comes in contact with the mineral deposits, the tips will die and the roots stop growing.

Also, unless the pH was SO high that it resulted in the creation of odd dissolved radicals (which is unlikely), your plant can still absorb anything in solution. Read this.