A "how-to" guide on acidification

[Steve Johnson]

Thank you Steve! Very informative article, I learned a lot.

You're welcome!

[AirWreck]

I am so astounded at how much things have changed in 20 years. 20 years ago I studied up on growing cacti. Now I'm revisiting the information and finding that everything I was told back then was wrong. I'm a bit sad and dispirited. But that's the way science goes: as new data comes along understandings and practices change. Lay people get upset about "the scientists and experts" constantly changing their minds- but that's how science works.

I used to try to use a pH meter but could never get it to work- readings were all over the place buffer fluids or not, and that's when the battery worked. I had just as much problems with having a working battery as I did with wild readings. Then there's the times the battery leaked and completely ruining the meter, forcing me to have to buy a new one. I'm going to go with a pH strips and I've been meaning to for sometime; I just keep forgetting to buy some. yeah sure, I may not be able to measure tenths of a pH but so much less instability with strips.

[Steve Johnson]

I used to try to use a pH meter but could never get it to work- readings were all over the place buffer fluids or not, and that's when the battery worked. I had just as much problems with having a working battery as I did with wild readings. Then there's the times the battery leaked and completely ruining the meter, forcing me to have to buy a new one. I'm going to go with a pH strips and I've been meaning to for sometime; I just keep forgetting to buy some. yeah sure, I may not be able to measure tenths of a pH but so much less instability with strips.

I'm sorry that you had a bad experience with your pH meter. My bad experience involved a Milwaukee Instruments pH 600, but user error on my part -- nothing wrong with the meter itself. When the last one crapped out on me, here's the meter I've been using for a year:

https://www.amazon.com/Poniie-PH2022Plu ... 776&sr=8-1

2-point calibration vs. the pH 600's 1-point calibration -- much better, and I get more accurate results with the Poniie PH2022 Plus. However, the calibration procedure is a bit labor-intensive since the meter has to be recalibrated unless it's used all the time (I use mine only 2-3 times a year). However, there's nothing wrong with test strips as long as they're giving you reliable results. After comparing results among a number of products, the best I've found are the 17 in 1 Pool and Drinking Water Test Strips made by MedLab Diagnostics. You can buy them on Amazon.

[AirWreck]

I still have pouches of unopened buffer fluids. I suppose I could test the test strips on the buffer fluids.
I'll have to find another source for buying test strips as I don't buy on Amazon.

This thread was interesting reading. I had long assumed that my tap water would be acidic because the local freshwater in the area tends to be acidic. Some of the creeks in the mountains here are so acidic now from acid rain that the native trout are having a hard time; the water was acidic to begin with because of the local geology. We don't have limestone here. The acid rain can push the creeks' pH down to around 3. However, I wasn't aware that municipalities will add ingredients to the water the tap water to make it alkaline. So, testing is truly in order.

Speaking of acid rain. If you're collecting rain water to use for your plants, its worth testing it. Acid rain isn't in the news anymore but it hasn't gone away.

[jerrytheplater]

I still have pouches of unopened buffer fluids. I suppose I could test the test strips on the buffer fluids.
I'll have to find another source for buying test strips as I don't buy on Amazon.

This thread was interesting reading. I had long assumed that my tap water would be acidic because the local freshwater in the area tends to be acidic. Some of the creeks in the mountains here are so acidic now from acid rain that the native trout are having a hard time; the water was acidic to begin with because of the local geology. We don't have limestone here. The acid rain can push the creeks' pH down to around 3. However, I wasn't aware that municipalities will add ingredients to the water the tap water to make it alkaline. So, testing is truly in order.

Speaking of acid rain. If you're collecting rain water to use for your plants, its worth testing it. Acid rain isn't in the news anymore but it hasn't gone away.

I use rain water all the time, a lot of it for my carnivorous plants which need very low pH, low mineral water. But, I also use it to mix up fertilizer solutions. There the concentration of the CO2 in the rain water is the major cause of a low pH. SO2, if there, will cause low pH too. But, the effect of the fertilizer concentration will overwhelm the effect of the low pH rain water.

Earlier you had asked about a water test for your water. If you are using a public water supply company for your water, you can ask them for a water test report. It won't test for all of the compounds used in fertilizers, but it will tell you some good information. If you have a well, then you need to get your water tested at a lab for a couple of hundred bucks. But then you can get exactly what you want. Just know that water can change over the seasons, especially if from surface water. By me, the use of road salt in winter has added a lot (35-50 ppm) of sodium and chloride in our reservoirs, which we drink.

Acid water in pipelines will dissolve old solder and add lead into your water. It will also corrode the pipes themselves. Some brass has lead added to it to make it easier to machine. That lead can dissolve. That is why pH is adjusted by water supply companies. And even some private homeowners will adjust their well water-not all. Water varies depending on where you live.

[AirWreck]

After comparing results among a number of products, the best I've found are the 17 in 1 Pool and Drinking Water Test Strips made by MedLab Diagnostics. You can buy them on Amazon.

I just tried those and found that the pH test only goes as low as 6.0. Since we are trying to have an average of 5.5, it leaves something to be desired. So, I just put in an order for a couple more from Fisher Scientific. One is a 3-8 pH test paper the other is a 1-12, iirc. Imo, an ideal range would be 4-9 but no one seems to make pH test paper with that range in mind. For now I'm just using distilled water with fertilizer added.

Otoh, using those Medlab Diagnostics drinking water test strips indicated I've got fluorine and possibly some lead in my drinking water. That was interesting. (I'm more worried about the lead paint in and on my house than I am from my drinking water)

[AirWreck]

So, I just recieved the rolls of pH test paper from Fisher Scientific. I got the 3.0 to 8.0 and the 1.0 to 14.0 test paper. The brand name is Hydrion. I tested the paper using 4.5 and 10.1 buffer solutions. Obviously, I couldn't test the 3.0 to 8.0 with the 10.1 buffer solution; however, I'm very confident of its accuracy in measuring acidic solutions. Otoh, the 1.0 to 14.0 was not very reliable for measuring acidic solutions. It was accurate for indicating alkaline solutions. So, I recommend the 3.0 to 8.0 test paper for measuring acidic solutions. Part of the problem with the 1.0 to 14.0 test paper was that its color straight off the roll is the same as the color for 5.0 pH on the color code chart. So, if you have water with a pH of about 4.5 to 5.5, you don't get a color change. That's why I recommend the 3.0 to 8.0 as its color fresh off the roll is the same color as 3.0 on the color code chart; so you get a color change no matter what pH you are testing > 3.0.

I think I know why the Medlab Diagnostics drinking water test strips indicated lead in my tap water. When I tested my tap water with the 3.0 to 8.0 test paper, it was indicating a pH of a little below 5.0. Not at all alkaline. The acidity may well be leaching lead into my tap water. So, you can't just assume that your tap water is alkaline. Do test it.

I have a spring fed pond in my back yard and I tested the water runoff from the pond. The pH appears to be a little below 4.0. Is this too acidic? Should I buffer it to raise the pH a bit? This weekend I'll test the water directly coming out of the spring.

[jerrytheplater]

I have a spring fed pond in my back yard and I tested the water runoff from the pond. The pH appears to be a little below 4.0. Is this too acidic? Should I buffer it to raise the pH a bit? This weekend I'll test the water directly coming out of the spring.

Spring fed pond: you will not be able to change the water parameters because new water is always coming in from the spring.

[Steve Johnson]

So, I just recieved the rolls of pH test paper from Fisher Scientific. I got the 3.0 to 8.0 and the 1.0 to 14.0 test paper. The brand name is Hydrion. I tested the paper using 4.5 and 10.1 buffer solutions. Obviously, I couldn't test the 3.0 to 8.0 with the 10.1 buffer solution; however, I'm very confident of its accuracy in measuring acidic solutions. Otoh, the 1.0 to 14.0 was not very reliable for measuring acidic solutions. It was accurate for indicating alkaline solutions. So, I recommend the 3.0 to 8.0 test paper for measuring acidic solutions.

Thanks for the recommendation! I seriously need to compile a brand-new "how to" guide since the info in my original guide is old and outdated. Before I do, I'll get a roll of the Hydrion 3.0 to 8.0 test strips and compare their results with my pH meter when I test a batch of my acidified water. If the results are the same, I'll go with the Hydrion strips -- quite frankly having to recalibrate the meter every time I use it is a pain in the you-know-what. And since the pH of my tap water is higher in summer than it is in spring (or it used to be -- I should check that), Hydrion strips are a lot easier to deal with for periodic testing. Here's another "if"...

• If the Hydrion 3.0 to 8.0 strips are indeed reliable, I'll recommend them as the first choice for my new "how to" guide on acidification.

Reliability is key -- for members living outside of the US who can't buy the Hydrion strips, a good digital pen-style pH meter is my fallback recommendation.

I have a spring fed pond in my back yard and I tested the water runoff from the pond. The pH appears to be a little below 4.0. Is this too acidic? Should I buffer it to raise the pH a bit? This weekend I'll test the water directly coming out of the spring.

Check out this nutrient availability chart:

pH_nutrient_ availability_ chart01.jpg (81.4 KiB) Viewed 231 times

You'll need to raise the pH more than a bit -- 6.5 is the "sweet spot" which makes all nutrients the most available to the plant. General Hydroponics makes a pH Up product with potassium hydroxide and potassium carbonate. Bloom City also has a pH Up with just potassium hydroxide, and I think it'll be better since carbonate in the water is counterproductive at least for cacti and succulents. Speaking of carbonate...

You might have calcium and magnesium in your pond water. If you do, they won't be carbonates, so the Ca and Mg will be immediately available to your plants. This isn't something you can test for yourself, so I'll point you to JR Peters:

https://www.jrpeters.com/lab-testing-services

A basic water analysis is all you need, $46 -- not bad. If you do have Ca and Mg in the water, you'll get the resulting amounts in ppm. This takes us to something I've posted a number of times elsewhere -- from hydrobuilder.com:

• "Magnesium and calcium go hand in hand, and are often an area where plants become deficient. Magnesium helps aid in the uptake and utilization of other nutrients, along with producing carbs and sugars to help during flower."

• "Calcium has a similar role in plants as in humans, helping produce strong cells and root walls. This leads to stronger plants. We've recently come to understand that calcium is actually the dominant nutrient in most plants." [My emphasis]

The take-away I get for our purposes -- Ca should be as high as or higher than N. My watering solution contains 48 ppm N per feeding -- between the Ca and Mg from my fertilizers and the Ca coming from the acidified tap water, we're looking at about 75 ppm there. Compared to the lower amounts of Ca my cacti got prior to last year, their growing quality has improved substantially. Long story short -- if your pond water does contain Ca (and Mg if it's there too), it'll do your plants nothing but good. Bring the watering solution from your pond water up to pH 6.5, and you're set.

[Steve Johnson]

I have a spring fed pond in my back yard and I tested the water runoff from the pond. The pH appears to be a little below 4.0. Is this too acidic? Should I buffer it to raise the pH a bit? This weekend I'll test the water directly coming out of the spring.

Spring fed pond: you will not be able to change the water parameters because new water is always coming in from the spring.

I think he was talking about buffering his watering solution, not his pond.

[AirWreck]

I think he was talking about buffering his watering solution, not his pond.

you are correct. Its silly to try to buffer the spring. I'm not putting the cactus plants into the pond. I'm collecting water from the pond with a bucket. The water to be buffered is in a bucket.

It'll be interesting to see your comparison results between the pH papers and your meter. The pH papers can give rough pH indications, such as 4.0 vs 5.0. However, you can assume in-between measures such as 4.5 when the shade of the pH turns into something that appears between 4.0 and 5.0 on the color chart because I did get results like that.

BTW: the price of the Hydrion 3.0 to 8.0 seems high compared to the 1.0 to 14.0 but you actually get 2 rolls of pH paper. That's why its more accurate for its measurement range. One roll goes from 3.0 to 5.5. The other roll goes from 6.0 to 8.0. One thing to know: they do have expiration dates. I'm not sure how well they work outside of their expiration dates. I suspect exposure to humidity may be the limiting factor. So, maybe store the pH papers in a container with a desiccant? I do have desiccants to keep my astronomy gear dry.

I'll look into those pH up products. I was hesitant to use baking soda to up the pH due to the sodium content. Your chart is very informative. Although, that makes me wonder about using wood ashes. I do have a lot of wood ashes from using a wood stove in winter. I've made lye water from wood ashes before.

[jerrytheplater]

I think he was talking about buffering his watering solution, not his pond.

you are correct. Its silly to try to buffer the spring. I'm not putting the cactus plants into the pond. I'm collecting water from the pond with a bucket. The water to be buffered is in a bucket.

Ha. I immediately thought of buffering the pond, probably because I've been talking about water lilies with friends on another forum. I have two tubs in my yard where I grow lilies and fish. Cross connection in the mind.

[Steve Johnson]

I'll look into those pH up products. I was hesitant to use baking soda to up the pH due to the sodium content. Your chart is very informative. Although, that makes me wonder about using wood ashes. I do have a lot of wood ashes from using a wood stove in winter. I've made lye water from wood ashes before.

Thanks for the info on the Hydrion strips. That chart came from SDK1 when he responded to my "Fertilizers explained" presentation, and yes it is very informative.

I read this article on Wikipedia...

https://en.wikipedia.org/wiki/Wood_ash

...and it sorta kinda looks like wood ashes will put calcium carbonate into your watering solution, making the Ca completely unavailable to your plants. I honestly think your best choice is going with a pH Up that has just potassium hydroxide and nothing more. I'm sure that Bloom City isn't the only company selling it.

[AirWreck]

Ha. I immediately thought of buffering the pond, probably because I've been talking about water lilies with friends on another forum. I have two tubs in my yard where I grow lilies and fish. Cross connection in the mind.

I kind of thought you might have been referring to the tub type ponds. You are correct that in your type of tub type ponds that the water pH in it needs to be actively controlled. My pond is a legit pond of at least 1/8 acre in size which is fed by a spring that flows at least 5gallons per minute. There's no controlling the pH in it. It is what it is. But having a means to get a reasonably accurate measurement of the pH is important. A person needs to know what they are starting with before making any adjustments to it and that's what I'm trying to do.

This year is the first year I've been watering my cactus plants with the pond over-flow water. I've never used it before because I'm often too lazy to walk down to the pond to draw a bucket from the over-flow. So, far the plants really seem to be responding well to it. The water has a lot of algae in it. There have been times past when I would collect the algae and apply it directly to my vegetable garden. The vegetables would do very well whenever I did that. So, I'm sure those same nutrients are going to the cactus plants- magnesium and what not. Obviously, I'm not applying rotting algae to the cactus plants. My main concern I had with using water from the pond was the chance of root rot on my cactus plants from introducing opportunistic organisms of which the cactus may not have a means to defend itself from. That doesn't seem to be an issue as I'm not seeing that happen. So, the live water from the pond appears to be safe to me to use. So, if I get better results this year from using the pond water than I did with using tap water, I may be more motivated to make that walk down to the pond to draw a bucket.

The next step is to use the Medlab Diagnostics drinking water test strips to test my pond water since those strips test for nitrates and nitrites. I need to remind myself which one it is that is desired- nitrate or nitrite? I wish magnesium and calcium were on the strips and I don't know if Total Alkalinity and Total Water Hardness can suggest calcium/magnesium presence or concentrations. That fact that there's algae growing in the pond indicates that there has to be some magnesium as magnesium is a component of chlorophyll.

[Steve Johnson]

I need to remind myself which one it is that is desired- nitrate or nitrite?

Both are desired, although this requires an explanation as to why:

Molybdenum.jpg (87.47 KiB) Viewed 47 times

Poinsettias are succulents, so it stands to reason that all cacti and succulents are particularly vulnerable to Mo deficiency. Can they get Mo from the soil in a soil-based mix? Let's find out From Gardening Know How (https://www.gardeningknowhow.com/garden ... bdenum.htm):

• "Molybdenum is a trace mineral important for plants and animals. It is found in soils that are alkaline with high pH levels. Acidic soils are deficient in molybdenum but improve with liming. As a trace element, molybdenum for plant growth is a moderately important catalyst for two very important enzyme activities. Plants can tolerate very high levels of molybdenum but do poorly with little to none of the element."

• "Sandy soils and acidic soils contain less available molybdenum for plant growth. The element is crucial to the functions of nitrogenase and nitrate reductase, two enzymes important for nitrogen-fixing and nitrogen reduction."

Plants growing in the open ground with the right soils have access to an unlimited supply of Mo from the soil, but plants growing in pots don't. This brings up another quote from Gardening Know How:

• "There are also many fertilizer formulations with molybdenum added, which will work well to increase the availability of the element in most plants."

Well, yes and no -- the fertilizers I've seen here in the US come up way short on Mo (if they even have it). Mike recommends 0.05 ppm per feeding (consistent with hydroponic applications), but the General Hydroponics 5-0-1 I use in my fertilizer regimen contains only 0.0008% Mo (0.005 ppm per feeding). Ferts should contain 10 times the amount we see with the 5-0-1 -- 0.008%. I made up for the shortfall with a sodium molybdate stock solution, so my watering solution includes 0.053 ppm Mo per feeding. After 10 years of being Mo-deficient, the addition of Mo last year was a contributing factor in the substantial growing improvements I've seen with my cacti. Check your fert -- if it has the right amount of Mo, you don't have to worry about it. But if it comes up short (or it doesn't have any at all), let me know, and I'll give you the recipe for my sodium molybdate stock solution plus the proper dilution rate per gallon for your watering solution.

If you have nitrate or nitrate and nitrite in your pond water, the right amount of Mo in your watering solution will make the N available to your plants. The next thing we should look at -- the ppm number(s) you get from reading a Medlab Diagnostics test strip. If nitrate/nitrite N is 50-100 ppm, I'd recommend against adding more N with a fertilizer. I've seen growers blowing their cacti up like beach balls, and this is due entirely to excess N. (Well, that and watering too often -- definitely not a good combination for the plants.)

I wish magnesium and calcium were on the strips and I don't know if Total Alkalinity and Total Water Hardness can suggest calcium/magnesium presence or concentrations.

You need hard water for that, and your pond water isn't hard.

That fact that there's algae growing in the pond indicates that there has to be some magnesium as magnesium is a component of chlorophyll.

Correct. Your pond's source is water percolating up through a dolomite (calcium magnesium carbonate) formation, and the water is already acidified for you. Since the Mg is available to the algae for chlorophyll production, it'll do the same for your plants. The only way to know the amounts of Ca and Mg in the pond water will be taking a sample to a test lab (hello, JR Peters!). Unfortunately there are no shortcuts on this one.