JesusFreak
Shohin
And wow the tap water was mid 7 and the rain water wasn’t much better. Kinda shocking. I’ve got Ph (up/down) solutions but is there any better way to drop the pH?
Mic dropIS it possible to return the pH meter for a refund? Reason, pH is a red herring. First, pH meters that cost less than $2000 are notoriously inaccurate. A research grade, or production grade pH meter runs from about $2000 thru $20,000 and really require a fair amount of chemistry training to use correctly. The goofy results you will get from a $150 pH meter, or a $40 pH pen, will send you into endless cycles of adjusting and re-adjusting water that was probably just fine in the first place.
For horticulture, the money is better spent on getting a good characterization of what your tap water is. The critical measurements are TOTAL ALKALINITY, and TOTAL DISSOLVED SOLIDS. With the two measurements, you can design a potting mix and fertilizer program that is perfectly matched to your irrigation water (usually tap water or municipal water). The full explanation is lengthy, use the BNut search engine and look for posts by me on pH.
WHen I was working for we shipped products to nuclear power plant projects, which required their pH needed to be certified as accurate. FIrst you needed to calibrate the meter with standards traceable to National Inst. of Standards (NIST, NIOSH, AASHTO & CRC-D) then you tested your sample, Then you retested the standards to verify that the calibration had not drifted in the 5 minutes since the first calibration was done. AND guess what, nearly every time the meter had to be recalibrated and the test run multiple times to get one "good set". pH is notoriously twisty. You will be adjusting and adjusting, and really have no clue where the pH of your water really is.
Fact: the root tips of plant's roots actively secrete buffers that modify the pH around the root tips to the ideal range for the root to absorb water, minerals and nutrients. Rain running off limestone will be somewhere in the 7.8 to 8.1 range, higher in colder weather. Yet the orchid, or fern or tree, if you measure the water film around the root tip on that limestone the pH will be near 5.5 give or take a little. Trees can fix this pH thing if the water at the roots does not overpower their own ability to BUFFER their environment.
Fact: All municipal water systems are required to buffer the pH of the water they distribute to a pH above 7.8, This is required so that the natural acidity of the water does not dissolve lead from the service pipe lines and from the brass fittings in the plumbing. Remember Flint Michigan? Hole bunch of kids with severely lowered IQ's and multiple health issue due to some bureaucrat deciding to not spend the money to properly buffer the water at the filtration plant. For economic reasons, most water utilities use the least amount of buffering chemicals they can get away with. So high pH from the tap is to be expected, and does not need to be worried about. Worry for your children if the pH of your tap water is less than 7.8.
Water has a buffer capacity. The minerals dissolved in the water determine what the buffer capacity will be. Rain water and DI, & Distilled water have near zero minerals, so have near zero buffer capacity. If you have a water glass with pure distilled or RO or DI water in it, just breathing across the surface of the water can cause enough CO2 from your breath to dissolve into the water and take the pH down from 7.0 to 6.2, nearly instantly. On the other hand, if you are drawing your water from a limestone aquifer near LaCrosse Wisconsin (think old style beer), the dissolved calcium for their wells is around 1400 mg / liter as calcium carbonate. This is HARD water. Which means it has a large buffer capacity. You could add 0.75 grams of concentrated sulfuric acid to every liter of LaCrosse aquifer water and you would just barely budge the pH.
The sad truth is that the pH meter tells you NOTHING about the buffer capacity of your water. But the annual water report your municipality is required by law to issue will indeed list the buffer capacity. The unit of measure for buffer capacity is TOTAL ALKALINITY, measured as milligrams per liter as calcium carbonate. If your municipal report does not list total alkalinity, it will likely list total dissolved solids. This does not directly indicate total alkalinity but it does tell you how much "stuff" is in your water. In the case of LaCrosse Wisconsin, total dissolved solids is nearly identical to Total Alkalinity, because the water is very pure, and the only contaminant is the limestone dissolved into the water from the deep aquifer. In Louisiana and parts of Mississippi, many aquifers are partially sea water. They are "fossil" mostly but not quite totally fresh water estuaries. The total dissolved solids will include a significant amount of sea salt, sodium chloride, in addition to the Calcium carbonates. So the difference in the two numbers, Total ALkalinity and Total dissolved solids gives you a direct measurement of how much sea salt and road salt is in your water.
If your total alkalinity is less than 150 mg/l as calcium carbonate or less than about 175 ppm total dissolved solids, your water is "pretty okay" and you absolutely should not make any attempt to muck about with adjust pH. You will be "going down the rabbit hole" of wrecking perfectly good water.
Total alkalinity above 150 mg/liter but below 350 mg/liter, this is medium okay water, considered good enough for landscape nurseries. Here you don't adjust the pH of the water, you adjust your potting media. Nurseries often use a composted bark based mix, with some peat moss and maybe other additives. This bark based mix will bring high pH down by binding up calcium from the irrigation water. They will also use fertilizer for "acid loving plants", that help bring down the amount of free calcium carbonate. This type of water usually has a total dissolved solids somewhere between 200 ppm and 450 or even 500 ppm total dissolved solids.
So in this case, they do nothing to the water, they change their potting media choices and fertilizer choices for medium alkalinity water.
Somewhere near 450 and up total alkalinity you are getting into the "hard water" situation. Here adjusting your potting mix alone will not be enough. Collecting rain water, blending rain water into your tap water. Top dressing potting media with elemental sulfur, using acid fertilizers and maybe resorting to fancy water treatments are the way to go. Only in this situation might a pH meter be vaguely useful, but if you start with an accurate total alkalinity test of your "average" tap water, you can do the calculations, and figure out your dose rates with out ever having to measure pH. Ph meters are only useful for those who can not do the maths. And the you better hope your meter is accurate.
I've typed enough for now, search for the many threads on pH. Re-wrap this pH meter up and return it for refund. If need be you can use the money to get your water tested for total alkalinity if you are on a private well. When we had the test done for the farm, Total Alkalinity was about $40 per sample and $20 per sample for total dissolved solids. Your local county ag extension agent will have a list of labs in your county.
Hope this helps. My fingers need to uncramp, so it will be a day or two before I answer follow up questions. LOL
pH drops, and paper strips, long term will be more accurate than an inexpensive meter. No matter how many decimal places it displays. @MrWunderful if you have some chemistry background, you can probably make a cheap meter work for a while. The glass tip of the probe will degrade over time, usually within 18 months it will be wildly inaccurate.
Thanks for responding. I went more indepth into your post because I had time and appreciate your insight. My city water report has alkalinity as (CaCO3) but listed in ppm instead of mg/L. (Its 114 btw) - Am I reading it incorrectly? Am I even looking at the correct data point? Thanks.
@Leo in N E Illinois when was the last time you used one of those pH sensors?
I worked with a lot of them in pharmaceuticals, and ours were not that expensive but they were medical production grade accurate, certified and all that. We steam sterilized the things and they still performed well after 5-10 times.
If the pH reading is unstable, either your probe contains air, or it's dirty.
Membranes and sensors have greatly improved over time, even though they still adhere to the basic principle.
I found cheap 30 dollar pens to be accurate to the decimal based on my calculated water pH and pOH.
That's actually pretty good. Good enough at least for home stuff.
I do agree that when you start measuring, you're entering the rabbit hole; one bad reading, poor calibration or just some dirt or air bubbles will cause a person to rip out his hair trying to adjust it. Especially if one doesn't understand the science behind it.
It took me half a year to get to know my sensors at work and everything that bothered them. And even then, they sometimes surprised me with poor readings.
I do however think that the cheap stuff can be surprisingly accurate nowadays. Compared to five or ten years ago at least.
Wow Leo my head hurts. Quite remarkable. I also bought a meter that test the Electrical activity in the water. But it seems that I don’t really need it either. And I only paid like $14 for each so it’s not that big of a deal. I was just trying to get it around 6-6.5 by adding some buffer to it.
Damn! I really wanted to drop that knowledge bomb!! friggin Leo strikes againFact: the root tips of plant's roots actively secrete buffers that modify the pH around the root tips to the ideal range for the root to absorb water, minerals and nutrients. Rain running off limestone will be somewhere in the 7.8 to 8.1 range, higher in colder weather. Yet the orchid, or fern or tree, if you measure the water film around the root tip on that limestone the pH will be near 5.5 give or take a little. Trees can fix this pH thing if the water at the roots does not overpower their own ability to BUFFER their environment.