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- fine-ass '22 harvest!
Ah! That's a grow formula, with those numbers,.. note the relatively low value on the P source, and that including the oxide portion (the analysis numbers are expressed in different ways, country to country, product to product),... So, you're low on P for a blooming plant for sure! Do you have other formulations? .... I have to disagree with HashMaster on the subject of the r-o test vs. even a simple pH probe like the A8... when used correctly, with well moistened soil, it's plenty close to the +/- 0.2 pH rating, compared to the professional units that do indeed run $200+,... I've tested color kits, r-o method, A8, against a borrowed pro' grade pH probe on samples before, and the A8 when used right, was the best out of the 3,... I believe the use of DI/RO on that final pour through before the collection of leachate in the r-o test is needed to make sure you're not adding potential buffering minerals (CaCO3) from the tap water, which will skew the results,.. the r-o method in general has several sources of measurement error inherent in it, some of which is addressed in that link method I gave,... HashMaster is right about the pH differences from the surface and down deeper,.. the root zone is a very dynamic place for pH, input/outputs from the roots, microbes, etc. make it vary some from place to place,.. one thing I like about the probes is that you can place the tip at different levels, and see how the pH is differing with depth and root proximity,... and you don't have to saturate the pot with water!
... EC and ppm are very closely related; ppm is an extrapolation of EC in fact,... the info they give tells you how hard your water is, or how concentrated a nute soln. is... No matter what you grow in, when there's a problem, this is the kinda data that matta'! ....
Oh my yes, low batteries make for wonky readings! 7.1 is damn nice water mate 
- likely, low ppm/EC,.... *** HashMaster is right again on pH'ing RO/DI water; it can give weird readings sometimes, I get this too,.. it has to do with the purity of the water, and ultra-low [H+/OH] conc.,... usually, from the atmospheric CO2 turning into carbonic acid in solution, you'll get a slightly acid pH in this type water...
...so, even with slightly dicey pH readings, it's safe to say you don't have overly acidic soil pH! In fact, it's too high (mid to low 6's is best range for true soil), so watch out for sudden yellowing on the top leaves, which is Fe defc. starting (Fe locks out fast above 7.0)... I'd say you have a lack-of P defc., and need to get more P in there right away,... I don't think you have to flush, try adjusting the water/feed inputs down mid to low 6's,...flushing is a stressor itself for the plant, to say nothing of the hassle and resources! Also, you may not necessarily have been adding in low 5's pH, the way the meter behaves with low batt's makes that estimate unreliable,... you can always flush later if the additional P input doesn't halt progression of symptoms,...
... EC and ppm are very closely related; ppm is an extrapolation of EC in fact,... the info they give tells you how hard your water is, or how concentrated a nute soln. is... No matter what you grow in, when there's a problem, this is the kinda data that matta'! ....
Oh my yes, low batteries make for wonky readings! 7.1 is damn nice water mate - likely, low ppm/EC,.... *** HashMaster is right again on pH'ing RO/DI water; it can give weird readings sometimes, I get this too,.. it has to do with the purity of the water, and ultra-low [H+/OH] conc.,... usually, from the atmospheric CO2 turning into carbonic acid in solution, you'll get a slightly acid pH in this type water... ...so, even with slightly dicey pH readings, it's safe to say you don't have overly acidic soil pH! In fact, it's too high (mid to low 6's is best range for true soil), so watch out for sudden yellowing on the top leaves, which is Fe defc. starting (Fe locks out fast above 7.0)... I'd say you have a lack-of P defc., and need to get more P in there right away,... I don't think you have to flush, try adjusting the water/feed inputs down mid to low 6's,...flushing is a stressor itself for the plant, to say nothing of the hassle and resources! Also, you may not necessarily have been adding in low 5's pH, the way the meter behaves with low batt's makes that estimate unreliable,... you can always flush later if the additional P input doesn't halt progression of symptoms,...
Vlad, you need to get something with real PK ooomph! GH Koolbloom is a nice choice, 0-10-10, or Grow More Sea Grow Bloom 4-26-26 (strong!), but whatever is handy/available readily will be fine, it's those higher PK#'s you need!
