What ph should runoff water be?

Richard Drysift said:

Runoff soil ph tells you nothing useful about your grow. You are only reading the results of what the water and nutrient ph is; not what the actual ph of the soil itself is. You need a soil ph probe and a good one at that to check the actual ph at the root zone. If you used a bagged soil it was likely ph balanced already. Adjusting the ph of the water does not adjust the ph of soil. Soil ph can only be adjusted or balanced by adding amendments like D-lime, sulfur, or potash, etc. If you were growing in a sterile hydroponic medium like coco coir then you would need to adjust the ph of your nutrient mix or water each time. Everybody goes out & buys a ph pen when they start growing thinking it's something they need but it's actually kind of a waste of money unless you grow hydro. It helps to have a ph pen to check your nutrient mix just to be sure it's not too much as the buffers should normalize the ph when mixed correctly but checking the runoff doesn't tell you anything useful. What kind of soil do you use?

Click to expand...

Blue Lab makes a soil pH probe that works for the Combo Meter or the pH meter. Not a pen. The seperate probe. Good to have with the regular probe to get the whole picture of the rhizosphere. Runoff and substrate medium.

Dr. Who said:

Fox Farm has a problem in it's charting.... Trio, or any FF nutrient product for that matter. Is not charted for the NPK needs of cannabis growing...
It can work. You just need to feed it at better amounts to be cannabis friendly.

Nice answer Chem...

Click to expand...

Works fine. Follow directions as low as 15% strength and work up to maybe 40% strength for regular feeding under 600 watts. Give only fresh water often for best results.

I don’t like that the individual bottles are not complete. It requires all 3 to properly fertilize or deficiencies will arise.

It also is low quality and contains sediment. And it builds up salt blockage fast and requires steady leaching.


I gave my “test” trio to another grower. He did fine too. I prefer a 1 part as I like it simple and can’t see any real differences between nute lines when used properly. I have tested a few different lines and types. Really doesn’t matter as long as they are complete.

MichiganMedGrower said:

Works fine. Follow directions as low as 15% strength and work up to maybe 40% strength for regular feeding under 600 watts. Give only fresh water often for best results.

I don’t like that the individual bottles are not complete. It requires all 3 to properly fertilize or deficiencies will arise.

It also is low quality and contains sediment. And it builds up salt blockage fast and requires steady leaching.


I gave my “test” trio to another grower. He did fine too. I prefer a 1 part as I like it simple and can’t see any real differences between nute lines when used properly. I have tested a few different lines and types. Really doesn’t matter as long as they are complete.

Click to expand...

I'm growing under cfls a mix of 6500 and 5000k. But what you're saying is I should never go full strength? Keep it low. And I'm still a newb so what do you mean by leaching? Like flushing?

zac graves said:

I'm growing under cfls a mix of 6500 and 5000k. But what you're saying is I should never go full strength? Keep it low. And I'm still a newb so what do you mean by leaching? Like flushing?

Click to expand...

Good questions. The intensity of light determines growth and the level of growth determines how much nutrients are needed.

You didn’t mention wattage but cfl is a low intensity lamp and likely your plants need less fertilizer.

I have fed 8oz dry bud plants at less than 50% strength that stayed green til harvest no problem.

Some guides use wattage as a factor. 1000 watt grow would need full strength bottled nutes. For some plants and strains that is true.

And leaching is “flushing” bit I only ever run an extra gallon through a 3 gallon pot when I see leaf stress from too much nutes.

Also with salt buildup it works better to leach with a low dose of nutes sometimes rather than just water. Salt attracts salt and the light mix will leave something for the plants after so it is usually only 1 step to correct overfeeding.

Hope this helped.

MichiganMedGrower said:

Good questions. The intensity of light determines growth and the level of growth determines how much nutrients are needed.

You didn’t mention wattage but cfl is a low intensity lamp and likely your plants need less fertilizer.

I have fed 8oz dry bud plants at less than 50% strength that stayed green til harvest no problem.

Some guides use wattage as a factor. 1000 watt grow would need full strength bottled nutes. For some plants and strains that is true.

And leaching is “flushing” bit I only ever run an extra gallon through a 3 gallon pot when I see leaf stress from too much nutes.

Also with salt buildup it works better to leach with a low dose of nutes sometimes rather than just water. Salt attracts salt and the light mix will leave something for the plants after so it is usually only 1 step to correct overfeeding.

Hope this helped.

Click to expand...

Definitely. But just a few more things.

I have 3 5000k 23w equivalent to 100w. And 7 6500k 13w equivalent to 60w. Totaling 720w. Me being stubborn and wanting to start ASAP, that's my setup.

And I only use a gallon for all 3 3gal pots. They each get a third and have been thriving from just that. Should I do a full gallon when flushing? When is too much and will be considered overwatering. They never experienced a lot at one time so would it harm them in any way

Fox Farm nutes definitely work but they arent formulated right. Low quality. I remember when they were up and coming back in the day. A small mom and pop outfit and still are. They kinda winged it with the whole semi - organic nute thing. I still think they are sorta shitty to be honest. Much better brands that put alot more thought into a base. Dont get me wrong. They work. Alot of people have had a fine crop come outta Fox Farm nutrients and soils but Ive ran skme nice sized grows back in the day and side to sides with other brands. One part simple Dynagro and Ionic as well blew it outta the water. Same with Botanicares Pure Blend Pro. Kinda sucked.

zac graves said:

Definitely. But just a few more things.

I have 3 5000k 23w equivalent to 100w. And 7 6500k 13w equivalent to 60w. Totaling 720w. Me being stubborn and wanting to start ASAP, that's my setup.

And I only use a gallon for all 3 3gal pots. They each get a third and have been thriving from just that. Should I do a full gallon when flushing? When is too much and will be considered overwatering. They never experienced a lot at one time so would it harm them in any way

Click to expand...

The equivelent wattage of a cfl is meaningless. The actual wattage is all you have on your plants.

And salt buildup takes time so you can still be fine but if you are feeding bottled nutrients I feel it is best to saturate the pot to 15-20% runoff and then wait to water again until the pots are very dry. Like 3/4 the way down.

I use a gallon of water/nutes to water a 3 gallon pot and check the runoff for ppm’s (ec) every time and take notes for later in case I need to review.

The drainage of the medium will affect how much water is needed. I use ocean forest with 20% large perlite mixed in. It holds more water than promix Hp did. So these are just guidelines.

Also try to keep the cfl’s as close to the plant all around as possible. Within a few inches for best results.

The website grow weed easy has a great cfl Grow guide.

http://www.growweedeasy.com/cfl-coco-coir

http://www.growweedeasy.com/cfls

since1991 said:

Fox Farm nutes definitely work but they arent formulated right. Low quality. I remember when they were up and coming back in the day. A small mom and pop outfit and still are. They kinda winged it with the whole semi - organic nute thing. I still think they are sorta shitty to be honest. Much better brands that put alot more thought into a base. Dont get me wrong. They work. Alot of people have had a fine crop come outta Fox Farm nutrients and soils but Ive ran skme nice sized grows back in the day and side to sides with other brands. One part simple Dynagro and Ionic as well blew it outta the water. Same with Botanicares Pure Blend Pro. Kinda sucked.

Click to expand...

I agree and stated above about the quality of fox farm. But all complete nutes can work fine. Side by sides are not a reasonable test unless you have taken the time to really dial in the nute usage.

I had stripped the leaves on this plant for harvest before taking the pic. It was grown in ocean forest with pure Blend Pro Grow only added once the nutrients in the soil were depleted.

MichiganMedGrower said:

I agree and stated above about the quality of fox farm. But all complete nutes can work fine. Side by sides are not a reasonable test unless you have taken the time to really dial in the nute usage.

I had stripped the leaves on this plant before harvest. It was grown in ocean forest with pure Blend Pro Grow only added once the nutrients in the soil were depleted.

View attachment 4057613

Click to expand...

Now thats a HUGE BITCH!!!

since1991 said:

Now thats a HUGE BITCH!!!

Click to expand...

I want to say thank you but she did all the work!

But thank you.

If ya look at it a certain way...we arent really "growing" anything. They do the growing. We just dust off the welcome mat and grease the door hinges every now and again. May even get fancy and wire up a door bell...but that's about it.

@ MichiganMedGrower --D e f o l i a t o r coming out party is in order perhaps? lol

say it isnt so, I was starting to like you

chemphlegm said:

@ MichiganMedGrower --D e f o l i a t o r coming out party is in order perhaps? lol

say it isnt so, I was starting to like you

Click to expand...

I edited my wording above. There was an itypo. I stripped the leaves FOR harvest before I took the pic.


Green til the end is the only way to get to a plants potential and truly potent marijuana in my opinion. And a ton of testing different levels of “flush” and fade.

Here is a Black Widow x Blue Lemon Thai I harvested last night. She still had her single baby leaves.

3 day’s ago still staked and tied up.


Stripped of its leaves and stakes and ties removed. I think untrained she would have been 6 feet tall easy.


Nice frosty pheno



Sorry to the OP. I can’t have chemphlem thinking I do silly crap like stripping healthy leaves.

I did have to “flush” the big budded plant above as I overfed her a bit and burned some leaves.

I call it leaching of course.

Lol.

Back to our scheduled program......

MichiganMedGrower said:

I agree and stated above about the quality of fox farm. But all complete nutes can work fine. Side by sides are not a reasonable test unless you have taken the time to really dial in the nute usage.

I had stripped the leaves on this plant for harvest before taking the pic. It was grown in ocean forest with pure Blend Pro Grow only added once the nutrients in the soil were depleted.

View attachment 4057613

Click to expand...

Just had to play the 3000 lb plant card huh?

frizfrazjaz said:

Just had to play the 3000 lb plant card huh?

Click to expand...

MichiganMedGrower said:

I edited my wording above. There was an itypo. I stripped the leaves FOR harvest before I took the pic.


Green til the end is the only way to get to a plants potential and truly potent marijuana in my opinion. And a ton of testing different levels of “flush” and fade.

Here is a Black Widow x Blue Lemon Thai I harvested last night. She still had her single baby leaves.

3 day’s ago still staked and tied up.
View attachment 4057630

Stripped of its leaves and stakes and ties removed. I think untrained she would have been 6 feet tall easy.
View attachment 4057631

Nice frosty pheno
View attachment 4057632


Sorry to the OP. I can’t have chemphlem thinking I do silly crap like stripping healthy leaves.

I did have to “flush” the big budded plant above as I overfed her a bit and burned some leaves.

I call it leaching of course.

Lol.

Back to our scheduled program......

Click to expand...

Nice plants, btw. I’ve read that getting equal parts soil from root zone and ro water, and let sit 24 hours,(shaking occasionally), would give an accurate reading on soil ppm and ph. Does this seem like it would work?

frizfrazjaz said:

Just had to play the 3000 lb plant card huh?

Click to expand...

Lol. It was only 30” x30” tied down.

But it took 8 quart size mason jars just to hold the dense dry buds. 6.1 oz top shelf buds and 2 jars of nickel size or smaller buds and larf and bud leaf trim.

But she went over 12 weeks. She has a souring sativa old school high with a nice background medical buzz.

I want to see a 3000 lb plant!

MichiganMedGrower said:

I highly disagree with your assertion that runoff tells nothing. It is a very useful informative tool when used properly.

It is to show changes over time. Not exact numbers at each test. If you are over fertilizing the runoff ph will likely be going down and the ppm’s up.

It is important to take the runoff the same way and amount each time for consistency.

This is standard practice in container crop production.

I even learned it from the premier horticulture (pro mix) website learning center.

I also learned about different types of lime and that pro mix adds calcitic lime and dolomite for immediate and long term buffering.

They suggest un adjusted tap water for the first week while the powdered lime charges. After that it starts to be available to the plants too. But it is added to the mix as a buffer not so much as a calcium or magnesium source.


And just an intersting fact

Agricultural lime is a mix of calcitic and dolomite and has a much better ratio of cal to mag than dolomite.

And adding 1/4 cup to ocean forest stopped my calcium deficiency. Which was caused by my well water going too soft during the dry summer and fall we had.

Sorry for the long post. I was up trimming all night and am high and wired.

Click to expand...

Sure ok maybe for a large grow where you want to monitor everything but for the average Joe starting out with a few plants in small containers checking runoff with a digi ph pen all the time just makes for a lot of confusion and tail chasing. I'm not sure what helpful info you can extrapolate from monitoring daily ph in a small soil grow but I do understand in a larger operation with more moving parts how that info could be useful over time. The minute I stopped bothering with ph (and ppms for that matter; no more bottles of stuff) growing got easier and the plants started to take care of themselves better than I ever could. Keep it simple.

frizfrazjaz said:

Nice plants, btw. I’ve read that getting equal parts soil from root zone and ro water, and let sit 24 hours would give an accurate reading on soil ppm and ph. Does this seem like it would work?

Click to expand...

Yes search for “slurry method” for checking ph.

Even field soil test workers use that method. I read a ph tester comparison article from a soil conservation worker a while back and they trust that method more than any probe style testers for consistency.

I do believe the ph is not usually an issue in potting mix with lime or oyster shell buffer.

I only check new bags after mixing in perlite or if there is a continuing problem. I don’t ph adjust my well water even though it shows 8.0 as it is relatively soft and does not affect the medium. I dont ph after adding nutes either. The solution will adjust to the soil mix. Unless it is very hard water or very acidic mixture over time.

And a fresh water leach usually resets the medium even with salt buildup. Which is usually the cause for the acidic ph readings. I may leach with light nutes as it helps remove more built up salts from the soil as salt attracts salt.

It is important to know source water alkalinity. As if it is high it I should like pouring some lime in each time.

Ro water has no buffer and causes other problems if things are not in balance.

If I had higher than 400ppm mineral content water I would mix down to 150-200 ppm with ro.

This is always mentioned in Greenhouse guides and Grow books but not on this forum so much.

My hydro store sold me an ineeded ro machine too though when I got started. I use it for filling the humidifier now.

Richard Drysift said:

Sure ok maybe for a large grow where you want to monitor everything but for the average Joe starting out with a few plants in small containers checking runoff with a digi ph pen all the time just makes for a lot of confusion and tail chasing. I'm not sure what helpful info you can extrapolate from monitoring daily ph in a small soil grow but I do understand in a larger operation with more moving parts how that info could be useful over time. The minute I stopped bothering with ph (and ppms for that matter; no more bottles of stuff) growing got easier and the plants started to take care of themselves better than I ever could. Keep it simple.

Click to expand...

I don’t worry about ph in a buffered potting mix. I check ppm’s and take notes as I run different plants at different stages perpetually. Easy to get into habits and overfeed a sensitive plant or underfeed a hungry one with all the varied strains. Usually 10-12 different plants at different stages a week to 2 weeks apart between veg and flower rooms.

I do agree that ph is almost never the issue causing the problem in soil type Grows. Low ph is usually caused by salt buildup and high ph by underfeeding and using hard water.

It is all self regulating when in balance like you say. I keep my Grow pretty simple. Water only in amended potting mix in veg and pure Blend Pro Grow only in flower once the soil is depleted of nutrients.

But the testing and note taking has helped many times. I can see what I did wrong and when. Or right lol.

since1991 said:

Blue Lab makes a soil pH probe that works for the Combo Meter or the pH meter. Not a pen. The seperate probe. Good to have with the regular probe to get the whole picture of the rhizosphere. Runoff and substrate medium.

Click to expand...

The Hanna Instruments HI99121 meter w/the proper pre-amplified probe is my choice. Brace your wallet..... We use 2 of these on the farm...... I don't have time to do slurry test's on fields. You meter the fields in many places, or a few. It depends on what was in the field and what is going in the next spring....... Container to container metering is made much simpler...With a meter...