Testing Runnoff

[Breezee77]

Howdy everyone… So I tested the run off after doing a fresh water… I'm using GH FloraNova Simple series in peat moss soil…. Once a week it calls for fresh water… I tested the run off at the end of week 2 of of flower and it is 950 PPM and the PH is 5.7…. Is this good? Is there a guide for it? The last feeding (the water before last) they were fed at about 6.4 PH and 700 PPM….

Any input is greatly appreciated!!!

 

[az2000]

Runoff ph is useful information. The most precise way to do it is called "NCSU Pour-Thru Method" (<<link).

Most people won't go to that extreme to measure runoff ph. Therefore, the variable is how long the water sat in the soil (affected by the soil's ph). At one extreme is immediate runoff. At the other extreme is the one-hour soak of the above method. It takes some experience to mentally adjust the runoff ph depending on how long the water sat in the container until it was displaced into runoff by more water.

If you get immediate runoff, you have to take the difference between poured ph and runoff ph, and subtract that difference from the runoff ph (if the runoff ph is lower than the pour ph). Or, add the difference to the runoff (if the runoff ph is higher than the pour ph).

If there was 15-30 minutes of soaking before displacement into runoff, you have to take (perhaps) half the difference.

This isn't very accurate, but in time you get a feel for how soak time (and quantity, with larger quantities containing liquid that didn't sit as long in the container) affects runoff ph.

Something which helped me a lot is a "Control Wizard Accurate 8" soil ph probe. (<<link) It's a $55 probe. A bit more accurate than those cheap $5 probes at Home Depot. This lets me see how ph changes as the medium dries. Also helps me confirm what I see in runoff. (Also aerates the soil, but you could do that cheaper with wooden dowel.).

Your runoff ph and ppm doesn't sound bad. I was overfeeding some organic'ish nutrients and got 5.0 soil ph in early flower, and 1250ppm runoff. Salt buildup. Reduced my feeding and I'm around 5.6 and 1050ppm runoff.

Are you seeing deficiencies? After you have nutes and medium dialed in you don't need to monitor runoff or probe soil. But, while working out a new variable (nutes, medium, supplement), I think both are useful tools.

 

[Breezee77]

Runoff ph is useful information. The most precise way to do it is called "NCSU Pour-Thru Method" (<<link).

Most people won't go to that extreme to measure runoff ph. Therefore, the variable is how long the water sat in the soil (affected by the soil's ph). At one extreme is immediate runoff. At the other extreme is the one-hour soak of the above method. It takes some experience to mentally adjust the runoff ph depending on how long the water sat in the container until it was displaced into runoff by more water.

If you get immediate runoff, you have to take the difference between poured ph and runoff ph, and subtract that difference from the runoff ph (if the runoff ph is lower than the pour ph). Or, add the difference to the runoff (if the runoff ph is higher than the pour ph).

If there was 15-30 minutes of soaking before displacement into runoff, you have to take (perhaps) half the difference.

This isn't very accurate, but in time you get a feel for how soak time (and quantity, with larger quantities containing liquid that didn't sit as long in the container) affects runoff ph.

Something which helped me a lot is a "Control Wizard Accurate 8" soil ph probe. (<<link) It's a $55 probe. A bit more accurate than those cheap $5 probes at Home Depot. This lets me see how ph changes as the medium dries. Also helps me confirm what I see in runoff. (Also aerates the soil, but you could do that cheaper with wooden dowel.).

Your runoff ph and ppm doesn't sound bad. I was overfeeding some organic'ish nutrients and got 5.0 soil ph in early flower, and 1250ppm runoff. Salt buildup. Reduced my feeding and I'm around 5.6 and 1050ppm runoff.

Are you seeing deficiencies? After you have nutes and medium dialed in you don't need to monitor runoff or probe soil. But, while working out a new variable (nutes, medium, supplement), I think both are useful tools.

Any chance you could spell out the math that you were explaining with my numbers? I mean, from what I think you meant was they were poured at 6.4 PH and then the runoff say 15 mins later was 5.7 PH, so are you saying take the difference (.325) and subtract it from the runoff PH (5.7) to get 5.4 PH? Wouldn't 5.4 be lower than you want?

Great information man… I did notice they are losing some of their color… They are due next time for a feeding and I believe that GH recommends 500-700 PPM to pour into them. They have been getting GH FloraNova series with Silica and Calmg added on feeding days…. If they are turning a little yellow, would you bring back FloraNova Grow? If you are unfamiliar, FN Grow is used at 1/2 with FN Bloom for first week of flower and then Bloom is used at full strength for week 2, which they go this week at full strength Bloom… They are going on to week 3 now, but I could add some grow back in? Would you up the PPM or add back in grow since it has nitrogen in it?

Thanks man!

 

[Rudi I&I Automan]

with weeds needs changing constantly during the day/day (24) or daynight (20/4-12/12 ) how can you hope top keep a log? sounds like your tryiong to climb a greasy pole with wet habnds.; geranted it would be great, but wit so many differant growth senarios to concider and take into concideration (door to house open for 20, mins, house tepm down by 1 degree overall etc,what will you be setting your max min values at for this?

 

[az2000]

Any chance you could spell out the math that you were explaining with my numbers?

Let's say you pour in 6.4 and runoff is 5.7.

1. If you saturated the soil, waited an hour, and poured a little more to displace only enough runoff to measure, 5.7 is representative of the ph of the soil. (At least when wet. If you used a decent soil probe you'd see it swing between 5.7 and 6.6 as it dries). It had enough time to reach equilibrium and wasn't diluted with too much pour-thru.

2. At the opposite extreme, let's say you water until you get runoff. No time to sit and equalize to the soil's ph. You're in a hurry to go to work, you just pour until 20% runoff which happens within 2-3 minutes.

soil ph = runoff ph - (pour ph - runoff ph)

4.8 = 5.7 - 0.9 (which is 6.6 - 5.7)​

The idea is, with so little time to equalize to soil, you extend the runoff ph even further.

3. If you water in intervals, pre-wetting the soil, pouring more in 5 minutes, maybe getting runoff after 2-3 pours over 10 minutes, you'd do something between #1 and #2. Maybe half the difference.

This is where a decent soil probe like I mentioned in my prior post can help you develop a feel for interpreting runoff.

Neither runoff nor the probe are "accurate." But, they can help you see trends. If you water the same way every time (3 stages of wetting, saturation and final pour/runoff over 15 minutes), and you see the runoff change from 6.2 to 5.6, and you start having ca or mg deficiency (which are available at higher ph), you might raise your input ph to 6.8 to hold the soil higher. And/or, do a water-only feed to reduce salt build up.

The probe helps too because if you confirm the wet soil is at 5.6, and you see it rise to 6.8 as it dries, you know you're getting decent exposure to the nutrient ranges. However, if it only raises to 6.2, you might question if you're watering too soon.

People get hung up about how runoff and probes aren't accurate. But, when working with new nutes or medium, I think it's useful information to help find the sweet spot. Once you have it dialed in you don't have to continue monitoring it.

In your case, you have to recall how long it took to get the runoff.

The photos look good, but it's hard to tell because they aren't under normal light (color corrected). I'd increase the feed ph to raise the soil ph and continue watching runoff.

 

[Rudi I&I Automan]

HAVE YOU ACCESS TO THE BOOK WITH THE LIGHTBULB ON THE COVER? IT'S THE ONE WITH SANDY HOLDING A LEBANIESE ?? MAIN COLA THATS THE SAME SIZE OF HIS HEAD GROWN UNDER SADONA'S i F MEMERY SERVES, i SEEM TO RTEMEMBER THEIR BEING MORE INFO OF THAT NATURE THEN THE GROW BIBLE i USE.
oOP'S
Wouldn't you give the PH of 2 the same value as the mother solution your using to water with ?

 

[Rudi I&I Automan]

yes for PH / TEMP AND TDS (SAME AS PH) http://www.facstaff.bucknell.edu/mastascu/elessonshtml/Measurements/MeasVolt.html

jUST TREYING TO FIND MY READINGS AND MATH FOR CONVERTIG THEM ALL :~)

tempriture and other natural voltage fluctuations within the soil will give incorrect readings, but not enough to worry about for our purposes.

Don't forget that natural organisms breaking down the soil will effect your final results too

 

[Breezee77]

Let's say you pour in 6.4 and runoff is 5.7.

1. If you saturated the soil, waited an hour, and poured a little more to displace only enough runoff to measure, 5.7 is representative of the ph of the soil. (At least when wet. If you used a decent soil probe you'd see it swing between 5.7 and 6.6 as it dries). It had enough time to reach equilibrium and wasn't diluted with too much pour-thru.

2. At the opposite extreme, let's say you water until you get runoff. No time to sit and equalize to the soil's ph. You're in a hurry to go to work, you just pour until 20% runoff which happens within 2-3 minutes.

soil ph = runoff ph - (pour ph - runoff ph)

4.8 = 5.7 - 0.9 (which is 6.6 - 5.7)​

The idea is, with so little time to equalize to soil, you extend the runoff ph even further.

3. If you water in intervals, pre-wetting the soil, pouring more in 5 minutes, maybe getting runoff after 2-3 pours over 10 minutes, you'd do something between #1 and #2. Maybe half the difference.

This is where a decent soil probe like I mentioned in my prior post can help you develop a feel for interpreting runoff.

Neither runoff nor the probe are "accurate." But, they can help you see trends. If you water the same way every time (3 stages of wetting, saturation and final pour/runoff over 15 minutes), and you see the runoff change from 6.2 to 5.6, and you start having ca or mg deficiency (which are available at higher ph), you might raise your input ph to 6.8 to hold the soil higher. And/or, do a water-only feed to reduce salt build up.

The probe helps too because if you confirm the wet soil is at 5.6, and you see it rise to 6.8 as it dries, you know you're getting decent exposure to the nutrient ranges. However, if it only raises to 6.2, you might question if you're watering too soon.

People get hung up about how runoff and probes aren't accurate. But, when working with new nutes or medium, I think it's useful information to help find the sweet spot. Once you have it dialed in you don't have to continue monitoring it.

In your case, you have to recall how long it took to get the runoff.

The photos look good, but it's hard to tell because they aren't under normal light (color corrected). I'd increase the feed ph to raise the soil ph and continue watching runoff.

Wow! If my run off is 4.8, then I'm worried lol… Going to try testing it next time using the said method you mentioned. Is that equation something you just made up or just a rough estimate?

So in my case, they were never watered over 6.5 PH because that's whats recommended on the bottle of the PH Down. Are you saying you would try it at say 6.8 or so next time if you were me?

Thanks for all the information! Any thing you would do regarding the nutrients PPM/nute levels I mentioned in the last post above?

 

[Silky Shagsalot]

unless your plants are displaying some sort of issue, don't worry about run-off ph. it's gonna be diff. coming out, cause you're washing out built up nutes. even when i'm in soil, i allow for a good bit of run-off.

 

[greenlikemoney]

I have a different view. The food I consume looks entirely different coming out than it looked going in. Thats how I feel about pH in soil. If your plant is healthy and you are feeding it properly pH'd food ( nutrients ), why drive yourself crazy analyzing your plants shit.

 

[az2000]

Is that equation something you just made up or just a rough estimate?

The math is something promoted on a different forum. But, it's not as simple as that because it depends on how long the water sat in the medium. Immediate runoff would be estimated with that "add the difference" formula. A one-hour soak, displacing just enough to measure (the NCSU Pour-Thru Method) should represent the soil's ph (wet ph) without any manipulation of the measurement. Anything in between (time soaking or volume displaced) requires some adjustment to the measurement (maybe adding part of the difference).

A good soil probe helps you see how various runoff (time/volume) relate to actual soil ph. It also lets you watch soil ph as it swings from wet to dry. I.e., 5.6 isn't that bad when you see how it spends considerable time at 6.2-6.6 as the soil dries. You don't get that visibility with runoff.

I agree with others that runoff or probing isn't hugely accurate or necessary. To me, it's only useful for new growers or when trying new nutes or medium. It can reduce surprises, eliminate a variable (ph) if there are deficiencies. Once nutes/medium are dialed, there's not much reason to continue.

I'm not familiar with GH Flora Nova. I agree with others, if you're not seeing signs of deficiency, I wouldn't worry about it. However, if you started to see defs, a history of soil ph (trend) would be good info to have. You can water/feed at a higher ph to pull the soil higher.

Whether you need to raise ph, I don't know. It seems common for soil to acidify going into flower due to salt accumulation. Also common to feed higher ph in flower because ca/mg are available at higher ph and craved more in flower.

I wouldn't make a huge conclusion about one runoff measurement. I don't think the measurement is that accurate. OTOH, if you feed at 6.4 and increase it to 6.6-6.8, that's not going to make a big change in soil ph either. If you don't see defs, it's probably better to leave things alone. OTOH, if you start having defs and continuous measurement of runoff (and soil probing) shows 5.0, you might want to water at 7.0-7.2 to pull the soil up higher, faster. (Or, consider the possibility of salt build-up and the need to flush).

I'd hold tight for now and continue measuring ph, developing your interpretation skills.

 

[Breezee77]

The math is something promoted on a different forum. But, it's not as simple as that because it depends on how long the water sat in the medium. Immediate runoff would be estimated with that "add the difference" formula. A one-hour soak, displacing just enough to measure (the NCSU Pour-Thru Method) should represent the soil's ph (wet ph) without any manipulation of the measurement. Anything in between (time soaking or volume displaced) requires some adjustment to the measurement (maybe adding part of the difference).

A good soil probe helps you see how various runoff (time/volume) relate to actual soil ph. It also lets you watch soil ph as it swings from wet to dry. I.e., 5.6 isn't that bad when you see how it spends considerable time at 6.2-6.6 as the soil dries. You don't get that visibility with runoff.

I agree with others that runoff or probing isn't hugely accurate or necessary. To me, it's only useful for new growers or when trying new nutes or medium. It can reduce surprises, eliminate a variable (ph) if there are deficiencies. Once nutes/medium are dialed, there's not much reason to continue.

I'm not familiar with GH Flora Nova. I agree with others, if you're not seeing signs of deficiency, I wouldn't worry about it. However, if you started to see defs, a history of soil ph (trend) would be good info to have. You can water/feed at a higher ph to pull the soil higher.

Whether you need to raise ph, I don't know. It seems common for soil to acidify going into flower due to salt accumulation. Also common to feed higher ph in flower because ca/mg are available at higher ph and craved more in flower.

I wouldn't make a huge conclusion about one runoff measurement. I don't think the measurement is that accurate. OTOH, if you feed at 6.4 and increase it to 6.6-6.8, that's not going to make a big change in soil ph either. If you don't see defs, it's probably better to leave things alone. OTOH, if you start having defs and continuous measurement of runoff (and soil probing) shows 5.0, you might want to water at 7.0-7.2 to pull the soil up higher, faster. (Or, consider the possibility of salt build-up and the need to flush).

I'd hold tight for now and continue measuring ph, developing your interpretation skills.

Gees man, thanks for all the information! Here's the deal, I see some deficiencies in some of the plants… Some of them, particular the ones closest to the CO2 tank are starting to yellow. Last water was just a fresh water and the PPM of the runoff was 950. I have only been giving them 700 PPM… You say I should increase nutrients? What PPM do you think would be the highest for week 3 of flower?

Also, what I could do is give them a heavy dose next feeding and then for the fresh water feed, I could do FloraKleen, which is supposed to get rid of the salt build up and kill all the nutrients from what I understand…. Would you recommend this?

Thanks again to everyone who is contributing to this post!

 

[az2000]

I could do FloraKleen, which is supposed to get rid of the salt build up and kill all the nutrients from what I understand….

I'd take it easy on remedies until you have a better understanding of what the problem is (feeding enough? salt buildup? ph?)

More pictures of the plants would help, emphasizing the deficient leaves. Pictures need to be under normal light or color balanced using photoshop.

I can't tell you whether to feed more or less. You'd have to google for floranova feed schedules, what others have done. There is a drain-to-waste schedule at GH. (<< link). It says 600-800 ppm is correct. Also says to use water-only once per week.

If your searches indicate you're feeding correctly, the next step will be to see the photos.

I'd be inclined to believe it's acidification. You said you use peat moss. Did you add dolomite lime? Peat tends to acidify. It shouldn't hurt to feed .02 higher if you're taking shots in the dark. If it is acidification, you'll at least start pulling it higher.

 

[az2000]

One thing I wanted to add: Resist the temptation to get additional runoff data by watering too soon. Watering too soon will not let the soil's ph rise as it dries, allowing the plant to experience a better range for some nutrients (like ca/mg). If your soil has become too acidic, limiting the upper range it will drift into compounds the problem.

 

[Breezee77]

One thing I wanted to add: Resist the temptation to get additional runoff data by watering too soon. Watering too soon will not let the soil's ph rise as it dries, allowing the plant to experience a better range for some nutrients (like ca/mg). If your soil has become too acidic, limiting the upper range it will drift into compounds the problem.

Ok, so they needed watered today, so had to use best judgement.. I have been following the feeding schedule to a T. Last feeding (a time before last fresh water), they were fed at 700 PPM. All notes they recommend, plus added Calmg and Silica and normal doses.

This time, because of the deficiency (mainly yellowing), they were fed at 1000 PPM… They were fed over 3 hours, given 3 doses of 1/2 gallons… Gees what a difference the time makes! They took 50% more water with no run off… May have been pouring the water in too fast before!

Anyway, when I added the normal nutes from GH's feeding schedule it read 800 PPMs… To get 200 more PPMs, 1 ml per gallon of GH FloraNova Grow was added… This was done because of the increased amount of nitrogen.

The run off that finally came out after the last dose of water read a consistent 5.8 PH, while the water that was poured was 6.7 PH… However, between the two plants, one read 1000 PPM on the run off and the other read 1300 PPM…

I was thinking because they were given 200 PPMs higher than GH recommends, for the next water, which just calls for plain water, to add FloraKleen, which is supposed to kill all the nutrients in the medium. What do you think about this?

Thanks for all the good info man! I'll get you an update if this fixes the problem.

 

[az2000]

I was thinking because they were given 200 PPMs higher than GH recommends, for the next water, which just calls for plain water, to add FloraKleen, which is supposed to kill all the nutrients in the medium. What do you think about this?

I wouldn't do that. If you're afraid you overfed, I would flush with 1-2x container-size pure or low-nute water. If you think you have a salt build up, I'd flush with 2-3x low-nute water. I don't think I'd use a flush additive.

If 5.8 is your soil ph (i.e., the runoff was after a good long saturation, and you displaced just enough to measure), you're in a good spot. It will rise to 6.6-6.8 as it dries. Even if it were 0.3 lower that wouldn't be too bad. It would still rise through a healthy range as it dries. A soil probe would confirm your runoff intrepretation and let you watch the ph between watering.

Photos of the deficient leaves would help (color corrected). I'd avoid doing anything extreme, even flushing. Maybe water only the next watering, with 20% runoff. It won't matter whether you ph the water unless you add some calmag to boost the ppm. Low-ppm water won't hold it's ph and will adapt to the soil's ph, not vice versa.

Did you google for other users of Flora Nova? Last night I found a lot of threads on different forums. For example, this one talks about amounts used, etc. http://www.420magazine.com/forums/frequently-asked-questions/112655-gh-floranova-feeding-schedule.html

I think you need some guidance on whether your ml/gal is correct, input and output ppms, importance of periodic water-only (compared to just weaker nutrients 100% of the time).

 

[Breezee77]

I wouldn't do that. If you're afraid you overfed, I would flush with 1-2x container-size pure or low-nute water. If you think you have a salt build up, I'd flush with 2-3x low-nute water. I don't think I'd use a flush additive.

If 5.8 is your soil ph (i.e., the runoff was after a good long saturation, and you displaced just enough to measure), you're in a good spot. It will rise to 6.6-6.8 as it dries. Even if it were 0.3 lower that wouldn't be too bad. It would still rise through a healthy range as it dries. A soil probe would confirm your runoff intrepretation and let you watch the ph between watering.

Photos of the deficient leaves would help (color corrected). I'd avoid doing anything extreme, even flushing. Maybe water only the next watering, with 20% runoff. It won't matter whether you ph the water unless you add some calmag to boost the ppm. Low-ppm water won't hold it's ph and will adapt to the soil's ph, not vice versa.

Did you google for other users of Flora Nova? Last night I found a lot of threads on different forums. For example, this one talks about amounts used, etc. http://www.420magazine.com/forums/frequently-asked-questions/112655-gh-floranova-feeding-schedule.html

I think you need some guidance on whether your ml/gal is correct, input and output ppms, importance of periodic water-only (compared to just weaker nutrients 100% of the time).

Ok, the two pics are under normal light so you can see the yellowing correctly. This is about 1.5 days after they were given a small dose of FloraNova Grow, which has more nitrogen/veg nutes in it. What deficiency do you think it is?

The next water they are due for a fresh water water, which is every other time because it takes 3-4 days per water, so a fresh water is called for every other time.

You are right on needing guidance for the runoff.. Thanks for linking that post, I started reading it, but haven't finished….

Very interested in your thoughts on what I should do. I'd feel way better if these girls where greener! Thank you!

 

[az2000]

Thanks for the pics. I agree, it looks like N def. Some of the leaves in the second picture look like mg def (green veins with yellowing between the veins.).

If it were me, I would

1. Do your scheduled water-only feed with 20-50% runoff. Just water-only should improve your soil ph if it's indeed acidic from salt build up. Getting significant runoff will give you a bit of a flush without the stress of a full 3x flush.

2. Foliar feed with

1/2 tsp/quart Epsom salt for mg
3 Tbsp/quart household ammonia for nitrogen.
Ph 6.5.
​

If you think you haven't been feeding enough, you could add 1/4 strength Grow.

You have to weigh foliar feeding with the risk of bud rot. If your humidity is high, use fans to accelerate drying. If too high, I wouldn't foliar feed. Also keep plants out of strong light until leaves are dry, water drops can magnify light and burn leaves. It's better if you have a surfactant additive which causes the water to spread over the leaf instead of collecting into beads. But, it's not necessary. Some people use a little non-anti-bacterial soap as a surfactant. But, I've never done that.

People commonly use ammonia at 1:10 strength which is 6.4 Tbsp per quart. And, 1 tsp/qt Epsom. You might start at half strength as I suggested. You could go 4-6 Tbsp/qt since your ammonia def is more pronounced. Maybe stay at 1/4 tsp/qt Epsom because your mg def isn't definite.

I'd avoid drastic action. I still think you need to locate other Flora Nova growers and find out if your input strength is high enough, if your runoff ppm is normal, etc. One post in that thread I linked to seemed to mention those parameters. And, develop more history/experience interpreting runoff ph to know if your soil is too acidic. You can feed .02 - .04 higher if you think it's marginally too low. That will pull it higher over 3-4 feedings. But, the water-only feeding will help. (You might add calmag to that feeding if you use RO water, which will also help make the water more buffered and have more affect on the soil's ph, if you're trying to pull it higher.).