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Soil pH: Most accurate measuring method...Household products for pH calibration?

maxbaker

New member
Hello everyone!

This is my first grow. Im growing under MH/HPS 250w in composted soil indoors.

Im 2 weeks in and all is going well.

The pH of my soil was ~9, the compost ~8.5 and my filtered tap water also ~9.

I bought some pH down and using some small samples I found out I had to water at a pH of 3 to get a run off of ~7. Couldnt get it lower without using a lot more pH down. (Ended up using 7mL/L)

This felt wrong and after asking for some help on this site someone told me that i wouldve killed my plant if i had continued to do so and that measuring run off pH isnt accurate. He explained that I should get a 1:1 ratio with distilled/purified water with a pH of 7 and filter it through a coffee filter then measure that pH. I did some more research and it seemed correct.

Unfortunately the only distilled water i can get my hands on has a pH of 7.5/7.7. I also live in a developing country without any weed tailored products.

Im using a pH pen which only came with one buffer solution for calibration. I measured the pH of the white vinegar I use and it was 2.4 which is was what it should be I guess. Tap was also ~7.5.

Any advice regarding the most accurate method to measure soil pH and what to do if I only have access to distilled water with pH of 7.5 for testing?

Are there any other reliable common household products i can use to calibrate pH?

I've read quite a lot online and have come across articles and forums stating that with good composted soil managing the pH isnt as important because of how the organisms break down and get fed to the plant but I would rather get my soil to 6.5 to be safe.

Any advice would be much appreciated!

Thanks :)
 

Mikell

Dipshit Know-Nothing
ICMag Donor
Veteran
Odd. Distilled water should test closer to 7 and lower once the seal (assuming it was bought in a sealed container) is broken and it begins to absorb CO2 from the atmosphere.

How broken down is the compost? It should lower with further aging.

I would suggest getting a two point calibrated pen. Litmus paper would be a cheaper alternative.

https://blog.hannainst.com/soil-ph-testing
 
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