Peter's Cal-Mag Excel

[aerides]

Thank you, Ray.

[aerides]

I also wondered how the pure water fertilizer would affect my water pH, which is 7.1-7.3. Since Argo's article states that RO water ranges from 4.0-5.5 and assuming that fertilizer designed for pure water would not further decrease pH, would it raise it? Waynes formula is buffered at 420#cal carb. or equiv. per ton. I looked at the fert. on your site, Ray, but can't see label too clearly. Assuming the RO formulas are all buffered about the same.

I'm guessing I'm looking for a final pH between 5.8 and 6.2 (?), which may mean I'd have to lower the solution? Ray, you mentioned familiarity with other growers in my area... do they have to fool with their pH?

Please forgive the clumsiness. I'm not chemically oriented - just doing a lot of reading and trying to assimilate rudimentary ideas. It's fascinating, but confusing.

Thanks so much,

John

[orchids3]

Wish pH meters were less expensive. Mine gave up a long time ago - it didnt last to long and required close attention to calibration when it did work. I shot for a pH of 5.8 to 6.2 when it did work. pH determines how well plants take up the required nutrients and my orchids deffinately improved with pH correction. Without an insturment to measure with I am flying by the seat of my pants (My aviation days). As long as I have the same bag of fertilizer (I bought 50 lbs) and use the same water I will be ok but as soon as I buy the next bag I will look for a way to test pH. It doesnt matter how good your fertilizer is with a bad pH because the plant may not take in enough to provide the necessary nourishment. pH result may vary from bag to bag and the water may vary a little due to inflow in the aquifers. Really need to get back to testing myself.

[kavanaru]

pH paper is a cheap way to test you final solution. It's not the optimal, but a good soluton so long you do not have a pH meter...

and by the way, it's also a very well accepted and used method even in high-tech scientist labs

[Ray]

Aerides,

Pure water has a pH of 7 - absolutely - but because it is totally unbuffered, almost anything can cause the pH to change. Most of us see acidification to the 4-5 range due to the absorption of CO2 from the air, forming carbonic acid. That is not a very strong reaction - it's a really dilute acid - so its effects are easily negated by the minerals in a fertilizer.

I do not know of the makeup of Wayne's fertilizer, but I do know it is different from the original, but the original, if added to your "almost pure" water, will give the correct pH with no need of further adjustment.