Great thread guys! We're getting a lot covered here.
My question- If your soil is at 5.5ph and you wanted to get it at 6.0ph on the dot, would a watering with plain sink water of 7.2ph do the trick just fine instead of using ph+?
No and yes!
You have to work out why your soil was at 5.5 in the first place, most store bought soil is pH6.3 out of the bag and above so what would have happened to lower this to 5.5???
Could it be the ferts you added to the soil, there pretty acidic and would probably do it, possibly if you have had wet soil sitting around for ages the soil microbes who thrive on anaerobic respiration (require no oxygen) might have made enough waste products to acidify the soil. Personally and for most of us we have simply added to much ferts.
So we add ferts to the plant and the pH levels go down but the levels go up as the plant eats them again. This is what you are seeing in the runoff, overfertilise and the pH gets worse and worse and also the ec/ppm will rise and rise.
And you thought that taking the runoff was a measure of the soil pH, really it is the soils pH plus the effects of anything futher you have added to it.
Now to chasing pH which is fruitless, you get a runoff of 5.5 and think i'll add 8.5 water to compenstae, of course the runoff comes out looking good at pH7 but this is not right because the runoff is now a mixture of the soil pH plus anything you have added i.e. ferts plus the effects of a completely different pH water. As you can see your runoff simply gives you a mixture of all the results.
So to do a correct flush we pH all water to similar to our soils original starting pH say around 6.5 to be safe and certain. We dont stop flushing till our runoff pH is close to the input water of 6.5. Only this way in watching the pH rise to the original soil pH level do we know we are flushing the built up salts/ferts out of the soil as these are what are affecting our pH in the first place and lowering it. If we flush at pH8 we are back to getting that mixture again.
Flush at the rough pH of the soil minus the ferts that way when the runoff gets close to this your soil will just be soil again with no ferts.
I had to work the same stuff out for soil and pH a while ago, even my explanation mught be confusing but im happy to explain any futher if there are questions. Believe me it gets more complicated and let me just say i dont bother pH'ing ferts and water in soil anymore as lime dose that for me and we have no conception of the acidity and alkjalinity produced by the two different types of nitrogen, Ammoniacal Nitrogen and Nitrate Nitrogen.
Let me know what your stuck on dudes. Peace
