"HELP" - PH & PPM reading confusing

This is a soil grow with ffof in 10 gal. pots, end of week 4 bloom. I've been checking my PH @ feedings from day one 6.3 - 6.5. Yesterday I received a new PPM meter, so I thought I would check nutrients PH & PPM @ feeding and check run off. PH was 6.3 going in and 5.9 run off in trays. PPM was 470 going in and 1040 run off in trays. I'm confused, thought ppm would be lower coming out. Also should I adjust my PH up to get a higher PH on the run off.

That's a very high runoff ppm for soil. You have buildup. This buildup is killing the microbes in the soil that naturally regulate the pH. Their little dead bodies are being fed on by bad bacteria which is dropping your pH levels.

You need to brew a compost tea. No nutrients, just compost and some molasses, maybe a little kelp and some worm castings but those are not needed. Do some reading on organics and compost tea while you're going about all this too. A good rinse with some quality compost tea will rebuild your soil's microbial population and wash out the salty buildup. Dirt IS nutrients, you just need bacteria to free it up.

Never "high-low" a system. The proper answer to a low pH in a soilless mix is using a large volume of nutrient solution at the correct pH until the media balances. In soil the easiest way to regulate your nutrient availability is to encourage the symbiotic relationship between roots and microbes in the dirt.

Your runoff ph is higher because there are more salts in it indicated by your EC/ppm runoff measurement. Lots of excess in your soil...might consider purging your medium before feeding anything more.

supercycle said:

...PH was 6.3 going in and 5.9 run off...

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JimmyToucan said:

Your runoff ph is higher because...

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Whoops! Ph *lower*....was thinking higher acidity and mistyped. The point was that when taking runoff measurements of ph the EC needs to be considered as well, otherwise people end up chasing their tails wondering why the ph is bouncing around.

Well, I watered again last night PH 6.5 and my run off PH was 5.9 & 6.0, my PPM was 145 in and the run off was 840 & 1340 on the 2 different plants. Ya think I need to FLUSH. I have the ff SledgeHammer.