Newbie to DWC. Lucas formula but high PPM's

Hey guys, long time lurker...first time poster. This is kind of a long-winded post but I want to make sure I provide all relevant info in order to get the advice I need.

I recently inherited a little girl in a container just slightly bigger than a solo cup. She is about 12" tall and is looking pretty healthy considering how root-bound she was.
Once I got her I switched her over to my 5 gal DWC setup...gently rinsing off the soil and all that. I'm completely new to DWC and after so much reading I decided to go with the Lucas formula for my first go.

When preparing the 3.5gals of nute mix of GH flora G-M-B at 0-8-16 for the 5 gal DWC pail I started to get a bit confused. On the asklucas site it says:

the gardner should mix nutes at the known recipe rate, then take a meter reading. WHATEVER that number is, regardless if its 1000, 1400, or any other number, THAT is the TDS of YOUR nutes in Your water, on Your meter

Click to expand...

I'm using a Milwuakee MW802 (formerly known as SM802) which is a 0.68 conversion..so I guess 0.7cf... freshly calibrated. Here are the figures:

Tap water baseline:
PPM - 250
EC - 0.38
PH - 7.8
Temp - 70f

Tap + 0-8-16 GMB (and PH down):
PPM - 1540
EC - 2.26
PH - 5.6
Temp - 70f

Now I always thought my water was "ok" I was very surprised to see it come out with such a high PPM. Before anybody comments, right now an RO system is simply not in the budget.

Now for the questions:
1 - With a tap water PPM at 250 should I be using the GH Micro 'hardwater'? Maybe I should get a water analysis done to determing how much ca/mg is in that 250pm.
2 - Is the overall PPM (ec over 2.0) going to fry my plant?
3 - What should I do? Perhaps lower the PPM by diluting the nute mix down some? I want to make damn sure this PPM and using the non-hardwater micro is OK as I plan on using the add-back method and setting my known PPM for my 0-8-16 nute strength is kind of key.

I appreciate any and all comments/suggestions and I know non-RO water is not ideal but its all i have and if I can make it work for this go-round I promise I'll invest in an RO system for the next time

Thanks guys!

-X

63 views and nobody knows? ;(

OK, First 250 PPM tap water is not that bad, anything under 200 is really good but 250 is still totally in the realm of normal and I wouldn't worry about it and don't bother adding anything in to deal with it for sure.

Secondly don't ever go by any nute directions when doing DWC as the rules of DWC do not apply to any other method. Since DWC is the only method in which the roots are completely saturated in nutes 24/7 the plants don't need nearly the amount of other methods. Your PPM levels are insane to me and just for an example I am 3 weeks into flower and only at 350 PPM and that includes my 185 PPM tap water. I increase at a rate of 25 PPM a week and usually stop increases when I reach 250PPM plus tap PPM.

If I were to raise my PPM levels any higher and I will begin to see plant issues so after many trials and experiments I find 250 PPM + tap PPM the perfect limit. I always get above 1 gram per watt and have hit as high as 1.45 GPW so don't let the small amount of nute PPM fool you into thinking your missing out.

If your using veg nutes I would drain and cut back to 150PPM plus your tap right away.

Way too high.

The most ive done was like 1.6EC in DWC with 5 foot monsters peak flower. And thats only because EC was dropping when I set at 1.4.

Use EC. PPM is different for all meters

BlackMesa said:

OK, First 250 PPM tap water is not that bad, anything under 200 is really good but 250 is still totally in the realm of normal and I wouldn't worry about it and don't bother adding anything in to deal with it for sure.

Secondly don't ever go by any nute directions when doing DWC as the rules of DWC do not apply to any other method. Since DWC is the only method in which the roots are completely saturated in nutes 24/7 the plants don't need nearly the amount of other methods. Your PPM levels are insane to me and just for an example I am 3 weeks into flower and only at 350 PPM and that includes my 185 PPM tap water. I increase at a rate of 25 PPM a week and usually stop increases when I reach 250PPM plus tap PPM.

If I were to raise my PPM levels any higher and I will begin to see plant issues so after many trials and experiments I find 250 PPM + tap PPM the perfect limit. I always get above 1 gram per watt and have hit as high as 1.45 GPW so don't let the small amount of nute PPM fool you into thinking your missing out.

If your using veg nutes I would drain and cut back to 150PPM plus your tap right away.

Click to expand...

See that's the frustrating part of all this. Many people say Lucas formula is safe and easy for beginners...but you get high PPM's 1300-1500 (or EC of 2.0+) which seemed crazy to me too. 150PPM + tap doesnt really make sense. Since you dont mix your nutes and then add to tap...you're measuring the PPM of the combined and its not a linear addition. 250ppm tap + 150PPM of nutes is not 400PPM, nor is it 200PPM unless the volume of the nutes and water was the same.

firsttimeARE said:

Way too high.

The most ive done was like 1.6EC in DWC with 5 foot monsters peak flower. And thats only because EC was dropping when I set at 1.4.

Use EC. PPM is different for all meters

Click to expand...

That's why I always include ec. It's the only common measurement unless you list your conversion factor. (Then the person converts it back to EC and figures out what their meter would read with their CF)

So, aim for 1.4EC...should I still be trying to get a 8:16 (or 1:2) ratio of Micro and Bloom as per lucas formula? Obviously 8ml and 16ml per GAL is way too high.

I thought the lucas formula was crap. Not enough nitrogen. I used only bloom and micro and had def. and burns.

Mix comes out too hot. Id use a one part like Ionic. Its PH stable and easy to use. Put like 5ml per gal calmag and the rest grow or bloom depending which stage youre in.

If all it is missing is Nitrogen why not add some gro as many do?

XavierFernandez said:

See that's the frustrating part of all this. Many people say Lucas formula is safe and easy for beginners...but you get high PPM's 1300-1500 (or EC of 2.0+) which seemed crazy to me too. 150PPM + tap doesnt really make sense. Since you dont mix your nutes and then add to tap...you're measuring the PPM of the combined and its not a linear addition. 250ppm tap + 150PPM of nutes is not 400PPM, nor is it 200PPM unless the volume of the nutes and water was the same.



That's why I always include ec. It's the only common measurement unless you list your conversion factor. (Then the person converts it back to EC and figures out what their meter would read with their CF)

So, aim for 1.4EC...should I still be trying to get a 8:16 (or 1:2) ratio of Micro and Bloom as per lucas formula? Obviously 8ml and 16ml per GAL is way too high.

Click to expand...

I use a PPM nute calculator that is pretty much dead on so the math is simple and it always adds perfectly. You should have a chart that shows (X) amount = (X) PPM level. Volume of fluid is irrelevant when you know the math for figuring out PPM amount for your nutes and 250 water is 250 PPM regardless if your testing 10 ML or 10 gallons so I don't get what your saying. I can figure out the combined PPM amount before combining and like I said it always adds up and is confirmed.

DWC IMO is far different then hydro because of the roots sitting directly in your nutes like I said and plants can't handle as much compared to a stream, mist or other method of flow. And PPM - Parts per million is a universal measuring formula that is universal as long as the manufacturer uses PPM as the representation of numbers. I have 3 PPM pens and all are calibrated and all give exact same results despite being made by different companies.

Regardless your nute levels are crazy high for such young and small plants.

BlackMesa said:

I use a PPM nute calculator that is pretty much dead on so the math is simple and it always adds perfectly. You should have a chart that shows (X) amount = (X) PPM level. Volume of fluid is irrelevant when you know the math for figuring out PPM amount for your nutes and 250 water is 250 PPM regardless if your testing 10 ML or 10 gallons so I don't get what your saying. I can figure out the combined PPM amount before combining and like I said it always adds up and is confirmed.

DWC IMO is far different then hydro because of the roots sitting directly in your nutes like I said and plants can't handle as much compared to a stream, mist or other method of flow. And PPM - Parts per million is a universal measuring formula that is universal as long as the manufacturer uses PPM as the representation of numbers. I have 3 PPM pens and all are calibrated and all give exact same results despite being made by different companies.

Regardless your nute levels are crazy high for such young and small plants.

Click to expand...

I agree the levels were high (I was just following the lucas formula) I have since lowered them to 1.4ec ( 980 ppm )

The volume of water is absolutely relevant when calculating combined PPM's of two separate concentrations. If I have 1 gallon of 200ppm and add 0.5 gallons of 0ppm (distilled) what is my resulting PPM? What if I added 3 gallons of distilled 0ppm instead? See? the volume is imperative.

Your understanding of PPM being a universal measuring formula is incorrect in this context.
If your meter uses a 0.5 conversion factor and mine uses a 0.7 conversion factor and we each test a liquid with a level of 2.0ec.

Your meter: 2000ec x 0.5cf = 1000ppm
My Meter: 2000ec x 0.7cf = 1400ppm

As you can see, if we speak only in terms of PPM you would be telling me my reading of 1400PPM is WAY TOO HIGH and should be closer to 1000PPM. meanwhile when you use the one common unit of measure, EC, our liquids are exactly the same concentration.

I suggest you do some more reading on the subject of PPM & EC before you hand out more advice based on incorrect information.

XavierFernandez said:

I agree the levels were high (I was just following the lucas formula) I have since lowered them to 1.4ec ( 980 ppm )

The volume of water is absolutely relevant when calculating combined PPM's of two separate concentrations. If I have 1 gallon of 200ppm and add 0.5 gallons of 0ppm (distilled) what is my resulting PPM? What if I added 3 gallons of distilled 0ppm instead? See? the volume is imperative.

Your understanding of PPM being a universal measuring formula is incorrect in this context.
If your meter uses a 0.5 conversion factor and mine uses a 0.7 conversion factor and we each test a liquid with a level of 2.0ec.

Your meter: 2000ec x 0.5cf = 1000ppm
My Meter: 2000ec x 0.7cf = 1400ppm

As you can see, if we speak only in terms of PPM you would be telling me my reading of 1400PPM is WAY TOO HIGH and should be closer to 1000PPM. meanwhile when you use the one common unit of measure, EC, our liquids are exactly the same concentration.

I suggest you do some more reading on the subject of PPM & EC before you hand out more advice based on incorrect information.

Click to expand...

I thought I explained it very clearly, I am able to accurately predict my PPM level give or take 20 PPM each and every time, I use a PPM calculator (software) Designed for my nutes that tell me ppm based on my specific combination at the time with the amount of fluid put into the equation. my 200 PPM water combined with my 200 PPM of nutes will always equal 400 (give or take 20 PPM) each and every time.

Now if I was silly and junked up the formula by adding 200 PPM tap with X amount of no PPM distilled then I would end up with an unpredictable result if I didn't first do the math and figure out what that PPM of water truly was.

All my meters do indeed use the same conversion factor so my results are the same, that was my point and YES PPM is a FACTUAL never changing number if you don't predict it, it's static! Our meters predict and estimate the PPM value but the real PPM number is always there so if using 3 meters results in 3 different estimations, that doesn't mean there is different PPM levels it just means the PPM level was estimated differently. To find the real actual PPM value you would have to use chemistry and evaporation.

All I was saying is that PPM is a real, universal thing sorry if I didn't feel like explaining why it's that way. Also I give advice because I am a DWC guru who has hit 1.45 GPW and have discovered much information on why DWC is so different than most perceive it.

PPM itself is an exact reading with a measurable concentration (mg/L) but without specifying the CF you cant tell me to aim for X ppm on a meter. Your meter and my meter can read different PPM if our conversion factors are not the same. Our meters predict it (using EC as the actual measured electrical conductivity value) and your software would calculate it (exactly).

In my example of 200PPM tap (if exact ppm is known) + 0ppm distilled (also known) you would not end up with 200PPM since you have increased the volume of water without increasing the TDS thereby diluting the concentration. 1 gal of 200ppm + 1 gal of 0ppm = 2 gal of 100ppm. That was my point. If we switch to mg/L for another example. 1 liter of 200mg/L + 1 liter of 0mg/L = 2 liters of 100mg/L. In the case of the nute addition to tap water it will ALMOST be a direct addition as the volume of nutes is very very low in relation to the volume of plain water you're adding it to; I will concede that.

Let's go back to my original question; I believe you stated "150ppm + tap" but never stated your CF.
So if you would aim for 150+250 = 400ppm and your conversion is 0.5 then you're saying I should be at 800ec or 0.8ec. If your meter is a 0.7 you're saying I should be near 571PPM.
If you're using a calculated non-meter-approximated value (which I believe you are using software...yet the known water PPM is only meter approximated) I would aim for the same 400PPM. Unless I got an exact water-quality test to get the true non-approximated PPM of plain water I dont think it makes sense to plug that number into software since with two different meters with different CF's we would get different PPM approximations for the same water.

XavierFernandez said:

PPM itself is an exact reading with a measurable concentration (mg/L) but without specifying the CF you cant tell me to aim for X ppm on a meter. Your meter and my meter can read different PPM if our conversion factors are not the same. Our meters predict it (using EC as the actual measured electrical conductivity value) and your software would calculate it (exactly).

In my example of 200PPM tap (if exact ppm is known) + 0ppm distilled (also known) you would not end up with 200PPM since you have increased the volume of water without increasing the TDS thereby diluting the concentration. 1 gal of 200ppm + 1 gal of 0ppm = 2 gal of 100ppm. That was my point. If we switch to mg/L for another example. 1 liter of 200mg/L + 1 liter of 0mg/L = 2 liters of 100mg/L. In the case of the nute addition to tap water it will ALMOST be a direct addition as the volume of nutes is very very low in relation to the volume of plain water you're adding it to; I will concede that.

Let's go back to my original question; I believe you stated "150ppm + tap" but never stated your CF.
So if you would aim for 150+250 = 400ppm and your conversion is 0.5 then you're saying I should be at 800ec or 0.8ec. If your meter is a 0.7 you're saying I should be near 571PPM.
If you're using a calculated non-meter-approximated value (which I believe you are using software...yet the known water PPM is only meter approximated) I would aim for the same 400PPM. Unless I got an exact water-quality test to get the true non-approximated PPM of plain water I dont think it makes sense to plug that number into software since with two different meters with different CF's we would get different PPM approximations for the same water.

Click to expand...

I believe it is indeed 0.7 but now you got me thinking that it shouldn't matter (at least for me) Here's why: I use 1000 PPM calibration solution that is 100% created to contain 1000 PPM, no estimating involved, so if my TDS meter is perfectly calibrated (which it is) My ppm value should be damn close to exact regardless of how it was estimated.

So question? Have you ever calibrated with liquid sealed solution? because if so I'm thinking we would be working with the same numbers (but perhaps you would have to correct).

I use GH 3 part series nutes and the calculator is dead on and only shows PPM values of the nutes in the amount that your adding. Now there is another culprate in boosting PPM numbers and thats PH down solution but that seems to neutralize and cancel itself off in a day (still working of figuring out the science of why that is).

So anyway if we used calibration solution would we both still get differnt numbers? If so then calibrating TDS monitors with solution should be step number 1 for anyone touching hydro,dwc, aero etc...

BlackMesa said:

I believe it is indeed 0.7 but now you got me thinking that it shouldn't matter (at least for me) Here's why: I use 1000 PPM calibration solution that is 100% created to contain 1000 PPM, no estimating involved, so if my TDS meter is perfectly calibrated (which it is) My ppm value should be damn close to exact regardless of how it was estimated.

So question? Have you ever calibrated with liquid sealed solution? because if so I'm thinking we would be working with the same numbers (but perhaps you would have to correct).

I use GH 3 part series nutes and the calculator is dead on and only shows PPM values of the nutes in the amount that your adding. Now there is another culprate in boosting PPM numbers and thats PH down solution but that seems to neutralize and cancel itself off in a day (still working of figuring out the science of why that is).

So anyway if we used calibration solution would we both still get differnt numbers? If so then calibrating TDS monitors with solution should be step number 1 for anyone touching hydro,dwc, aero etc...

Click to expand...

That makes sense to me. I was calibrated with 1500 Ppm solution and 7.01.ph right after I bought it on Monday. I checked it last night for fun and it's still bang on.

LUCAS FORMULA is designed for R/O water. And 250ppm tap is bad. Not drinking water bad, but IMHO it's garbage for hydro.
Yes you can get by... but who here wants to just "get by" on their grows?

BlackMesa said:

I thought I explained it very clearly, I am able to accurately predict my PPM level give or take 20 PPM each and every time, I use a PPM calculator (software) Designed for my nutes that tell me ppm based on my specific combination at the time with the amount of fluid put into the equation. my 200 PPM water combined with my 200 PPM of nutes will always equal 400 (give or take 20 PPM) each and every time.

Now if I was silly and junked up the formula by adding 200 PPM tap with X amount of no PPM distilled then I would end up with an unpredictable result if I didn't first do the math and figure out what that PPM of water truly was.

All my meters do indeed use the same conversion factor so my results are the same, that was my point and YES PPM is a FACTUAL never changing number if you don't predict it, it's static! Our meters predict and estimate the PPM value but the real PPM number is always there so if using 3 meters results in 3 different estimations, that doesn't mean there is different PPM levels it just means the PPM level was estimated differently. To find the real actual PPM value you would have to use chemistry and evaporation.

All I was saying is that PPM is a real, universal thing sorry if I didn't feel like explaining why it's that way. Also I give advice because I am a DWC guru who has hit 1.45 GPW and have discovered much information on why DWC is so different than most perceive it.

Click to expand...

Didnt you say it was right on the money or something like that?? Give or take is literally the exact opposite. Js

LivingCanvas said:

LUCAS FORMULA is designed for R/O water. And 250ppm tap is bad. Not drinking water bad, but IMHO it's garbage for hydro.
Yes you can get by... but who here wants to just "get by" on their grows?

Click to expand...

+1
Lucas Formula was designed to be used with a full and cyclic pH swing and ONLY R/O water. Cannabis is a dynamic accumulator and that 250ppm is heat, bad flavor and darker ash (unless it's all calcium, then you get bright white ash). Only plain R/O water is used to top off the reservoir, otherwise it messes with the pH swing.

Screw the ec readings anyway, look at your plant. Dark green? Too much nutes. Light green, deficiencies? Too little. Lucas Formula is light on mag, plenty of nitrogen for flower. I use .5g of epsom per gallon when I first mix a flower res, none is needed after that. As long as you have a full and cyclic pH swing, you won't see deficiencies.

Once you know what your plants want, take a reading and write it down. Use that as your maximum the next time. DWC is actually a lazy man's hydro to smashing success, once you get your brain wrapped around it.

15+ years with dwc and I grow cannabis like this...

See the nice plump trichomes on this DRY cannabis? It's all about terpene and cannabinoid production and retention!

Holy necromancer! This is 3 years old...

I've since moved on to complete 8 successful grows and use recirculating dutch buckets with a custom blend of salts and handmade cree COB led's. I'm good, but thanks for the input.

Douglas.Curtis said:

+1
Lucas Formula was designed to be used with a full and cyclic pH swing and ONLY R/O water. Cannabis is a dynamic accumulator and that 250ppm is heat, bad flavor and darker ash (unless it's all calcium, then you get bright white ash). Only plain R/O water is used to top off the reservoir, otherwise it messes with the pH swing.

Screw the ec readings anyway, look at your plant. Dark green? Too much nutes. Light green, deficiencies? Too little. Lucas Formula is light on mag, plenty of nitrogen for flower. I use .5g of epsom per gallon when I first mix a flower res, none is needed after that. As long as you have a full and cyclic pH swing, you won't see deficiencies.

Once you know what your plants want, take a reading and write it down. Use that as your maximum the next time. DWC is actually a lazy man's hydro to smashing success, once you get your brain wrapped around it.

See the nice plump trichomes on this DRY cannabis? It's all about terpene and cannabinoid production and retention!

Click to expand...

im using jungle juice lucas formula for my 5 gal dwc, although im only mixing 08 ml micro in its own 1 gallon - 16 ml bloom in its own 1 gallon - and 3ml Humbolts secret golden tree in its own gallon, shake each vigorously then add the 3 gallons to the bucket . so im basically cutting the single gallon lucas formula into 3 gallons of OS water and gettin 380ppm working steadily. Whereas my buddy is using aero and only cuts 08-16-03 with 2 gallons of os water and its working wonderfully