pH help!

[treezzz]

hi everyone. i just started my first indoor grow in soil and i am trying to keep a low budget. i happened to find a bottle of "pH up" in my closet that is used for raising the pH of hot tub water. it is one hundred percent sodium bicarbonate. i was just wondering if anyone knew if this is safe to use in my water for my mj plants if i need to raise the pH. also is using gardeneing pH up and down products a cheap and effective way of controlling the pH of my water/ nute solution? thanks for any responses in advance!

 

[Goldengoose7]

hi everyone. i just started my first indoor grow in soil and i am trying to keep a low budget. i happened to find a bottle of "pH up" in my closet that is used for raising the pH of hot tub water. it is one hundred percent sodium bicarbonate. i was just wondering if anyone knew if this is safe to use in my water for my mj plants if i need to raise the pH. also is using gardeneing pH up and down products a cheap and effective way of controlling the pH of my water/ nute solution? thanks for any responses in advance!

NO!

Baking Soda can be used as a DIY pH UP but it can be risky if you use too much. Better to use pH UP intended for plants.

I suggest buying the pH kit from General Hydroponics. It's under $20.00 online.

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[Droopy Dog]

If you're in soil, adding dolomite lime will take care of pH issues along with cal/mag issues.

DD

 

[Goldengoose7]

If you're in soil, adding dolomite lime will take care of pH issues along with cal/mag issues.

DD

That's good advice provided that his soil pH is too low. The Lime has a pH of close to 10 so it can cause problems if the soil is already above the preferred 6.2 to 6.8 range. If just the right amount is mixed into the soil at potting time, Dolomite Lime is great for stabilizing soil pH, but harder to get right just using a top cover. However, I find with Cannabis that it is better to ride the high side (alkaline) than the low side (acidic).

What I do is UP the nutes to 6.5 but I water with our tap water which is mountain spring well water with a stable pH of 7.05. For a time I started lowering my plain water to 6.5 and started having low pH issues with one of my most valuable plants! It never recovered, so now I am back to my multi-decade practice of only pH adjusting nute solutions and leaving the plain water alone.

If you have a Chlorine problem, it pays to fill several containers with the tap and let them sit for 24-48 hours to evaporate off the Chlorine before use.

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[treezzz]

thank you both for the help. i think i'll check out GH's pH adjusting kit like you suggested.

 

[Droopy Dog]

Dolomite lime has a pH of 7. Where did the 10 come from?

And lets face it, just about every bagged *soil* is actually a peat based soiless mix and 49 times out of 50, on the acidic side.

IDK though. I'm mainly a gardener (soil and container), and do mj in the winter for something to do. Anyway, I get the pH right in the soil or the mix (I make my own), and that's it for the season or the cycle.

I use better than 100 gals to water everything and couldn't even conceive of pHing that amount of water. Other than mj growers, I can't recall ever hearing of farmers or gardeners pHing irrigation water. They let the soil do it. Commercial hydroponics, IDK and have no knowledge on that. Most certainly agree with you about plain water for irrigation.

Not trying to flame or slam here, we are pretty much in agreement, except for that pH of 10 thing. LOL But, I just feel if people would get their soil/mix right with lime, or oyster shell flour, or something similar, all this pHing would simply not be necessary.

DD

 

[Goldengoose7]

Dolomite Lime is a VERY alkaline mineral and as a result its pH value is high. However, this doesn't mean that it makes your soil rise to 9.5 or 10 or whatever its own pH is if you use it.

This is because it will always interact with whatever it is mixed with. It not only can raise the soil pH of acidic soils, it primarily helps to stabilize the pH of soil and that is why many people use it, especially on lawns and ground cover.

When this lime is added to a soil that is overly acidic, it neutralizes the acid and stabilizes the soil and over time prevents the treated soil from drifting out of range again. With an existing pot that is suffering from a pH that is too low (below 6.2 for Cannabis) adding a few cups of Dolomite Lime to the top surface of the potted soil (top cover) and watering, will eventually help to raise the pH back to the optimum range of 6.2 to 6.8.

I totally agree with you that much of the obsession with pH by Cannbis growers is misplaced. As you said, if you start with a good soil mix that has ingredients in it to help stabilize and maintain the proper pH, you shouldn't need to pH your irrigation water.

I never bother doing this with any of my food crops, and only ran into problems with a potted plant when I have wavered from that practice and started pHing my irrigation water. Now, I just raise the pH of nute solutions back up to around 6.5 before feeding it to my plants, but I don't do anything to the tap water I use for irrigating the Cannabis just like all our other crops growing next to them.

I think folks would have a lot less soil problems if they stopped getting so carried away with pHing everything they put on their plants unless they have some terrible tap water that is super high or super low.

 

[ShutUpDonny]

Brotha, can you spare a clarification?

I'm somewhat confused about this idea of pH-ing nutes vs pH-ing irrigation water. Are you saying that you pour the water on if its pH is reasonable, but only adjust pH when you apply nutes +/- weekly?

And to do the inevitable Noob Maneuver™ and make this discussion more about me - I just want to double check that I'm testing/adjusting pH correctly. When I _water_, I collect the first of the runoff and test it. If runoff is 6.2 - 6.5 I'm all good. But if it is (hypothetically) 6.7 and the nute solution I use is 6.9, then next time I feed I should pH-DOWN the nute solution to 6.4, hopefully accounting for the soil reducing pH by .2 and bringing the runoff to read 6.2?

In other words I should water as needed, adjust pH only through adding nutes weekly... and oh yeah - stop worrying so much about pH!

Thanks!

 

[spice]

Soil Acidity and Liming (Overview)