Help with ph in soil please!

Im 5 weeks into 12/12 and I noticed leafs turning yellow and I'm sure it's not nit def so I checked ph in soil. I'm using ffof and ph is just under 8 what can I do to fix ph? Just flush with water with ph in the 5 range? Or is there something else to do that's better. Any advice is appreciated.

I was having similar problems in the beginning of my grow. Do not flush with water with a pH of 5. Flush with water with a pH of 6.2-6.5. Keep flushing until your runoff pH is the same as the water going in.

myself i would just feed @ around 5.8-6.0 for a few feeds and keep checking ph until it comes down to 6.2-6.5 range,but alter ego's way is also not a bad option.gl

Here's a link with the basics of pH in soil and solutions for raising/lowering pH: http://www.cannabis-spain.com/ph-soil.htm

If you're comfortable with safely handling lab reagents, you can use nitric acid (NHO3; pH down) and potassium carbonate (K2CO3; pH up). Some important things to remember: 1) dilute the reagents with distilled water before adding them to your watering can; 2) add the reagent to the water, not the other way around; 3) use glass/Pyrex implements (graduated cylinders, stirring rods, beakers, etc.) for mixing/storage; 4) store reagents in their original containers in the refrigerator or freezer (or at the very least a cool, dark, dry place).

The "pH up" and "pH down" solutions you make should be stored under similar conditions (#4 above). Amber/cobalt glass dropper bottles (with glass droppers) work well for dispensing them into the water. If your water supply is fairly neutral, 500mL of azeotropic (68%) NHO3 and 500g of K2CO3 should last for several years. The liquids you'd buy in a hydro/gardening store are usually made from these (or comparable) chemicals. The commercial solutions are just watered down and ridiculously overpriced.

Like "Alter Ego" wrote; don't adjust the pH too rapidly. The water you use to adjust pH should only be slightly lower than the low range of "ideal". Remember; 1 "pH" (unit of measurement) is 10x as acidic/basic as the next. You definitely want to get the pH down but drastic changes of any kind are generally a bad idea. You may want to figure out what caused such a high pH in the first place (medium, nutes, water supply, etc.) so you don't end up in the same situation again. Good Growing!

Thanks for link. If I need to add lime can I mix in w water? And how much per gallon?

1 tablespoon per gallon of soil

you can just add it as a top dressing...add 1 tablespoon lime per gal to top of soil and then just water the plant

Chillintxstlye said:

Thanks for link. If I need to add lime can I mix in w water? And how much per gallon?

Click to expand...

It took me a while to get this finished; looks like "Trulife69" already addressed this but I'll add my comments anyway:

I presume that you mean dolomite lime (as opposed to hydrated lime). I wouldn't bother trying to dissolve it. In fact, it's probably easier to distribute it evenly if you just sprinkle it onto the soil and wash it down with clean pH-adjusted water. I'd suggest going to the acidic/low end of "ideal" as far as the pH goes. Let it chill overnight or something before you check the pH. It's really best added to the medium before the grow begins (or when transplanting) but it should still buffer/stabilize pH if you sprinkle it onto the top.

I've never used it indoors but I'd agree that a tablespoon per gallon would definitely work. I was going to suggest a teaspoon/gallon as a "first try" just to see how the mix reacts. Remember that it also provides calcium and magnesium to the plants so you don't need a cal/mag supplement if you use dolomite lime.

My grandfather used it every three to five years on his veg garden (depending on the soil conditions). Too much or too often isn't good for the soil. We never really measured or anything but a 50-pound bag covered a ~30'x~100' patch and the veggies thrived. Of course, we added compost on even years and seasoned horse/cow manure on odd years before the first frost. We also did complimentary plantings (marigolds and whatnot) to control pests and it worked really well.

Soil is a natural buffer and does not need phing I never have and never will, no need to over complicate growing.

2 tbs elemental sulfur worked in and watered in.

Dub..I must be the only guy on the planet that's soil doesn't naturally buffer...I have a bluelab soil tester and my results are far different than the "natural" buffer. Im not saying stuff cant grow but to obtain optimal ph in soil I think it would be better to pay attention to it and adjust if you need to than just winging it and hoping for the best