Lucas Formula falling short on PPM for CoCo

mas3372

mas3372

Active Member
I am using the Modified Lucas formula for CoCo and am hand feeding through the top every day.

I have been using the modified version which looks like this

6ml Micro per Gallon
9 ml Bloom per Gallon
1ml Cal/mag per Gallon

and I am adding 1ml per Gallon Super thrive.

My starting water is tap water which is 70ppm with an initial pH of 9.1

I added the nutes in that order mixing well inbetween and I am only coming up wiht 550ppm of TDS.

The pH comes down to 5.8 without any pH down.

I thought the lucas provided 900-1000pppm, why am I only coming up with half of that.

I make a 5 gallon batch at a time. Today I incresed micro to 8ml per gallon and bloom 12ml per gallon keeping the micro to bloom ration the same. Left the calmag and superthrive the same and came up with 700ppm TDS.

What am I doing wrong?

the plants are only in veg and growing 1/2 inch a night which is good but I want to get the most growth I can. I plan on keeping the formula the same for bloom as well since the formula states this is okay.

Any ideas?
 
tip top toker

tip top toker

Well-Known Member
I'm not quite sure how you're growing but it doesn't sound like you should be using the lucas formula. The lucas formular is used with big reservoirs of feed. So that when it is half empty, the grower can fill it back up and reliably maintain a good food ratio. It is not used when adding nutrients to plain water.
 
mas3372

mas3372

Active Member
I'm using coco in 3 gallon pots. I water each plant in the morning with the nutrients by hand out of a watering can throught the top. As soon as a little water dibbles out the bottom, I stop. Do this everyday. They are growing great; healthy leaves, nice and green and 1/2 inch growth per day with 60watts cfl per ft2.
 
mas3372

mas3372

Active Member
No, I make a 5 gallon resevoir that lasts 2 weeks (i'm only in veg). When I throw them into flower, I will probably mix a batch every 2-3 days. I don't recycle the nutrient water, once it goes through the coco, it goes down the drain.
 
homebrewer

homebrewer

Well-Known Member
mas3372 said:
I am using the Modified Lucas formula for CoCo and am hand feeding through the top every day.

I have been using the modified version which looks like this

6ml Micro per Gallon
9 ml Bloom per Gallon
1ml Cal/mag per Gallon

My starting water is tap water which is 70ppm with an initial pH of 9.1

I added the nutes in that order mixing well inbetween and I am only coming up wiht 550ppm of TDS.

The pH comes down to 5.8 without any pH down.

I thought the lucas provided 900-1000pppm, why am I only coming up with half of that.


What am I doing wrong?
Click to expand...
You're probably on the NaCl scale and that's why you're coming up with 550ppm (make sure to calibrate your meter every few weeks). I'm on the 442 scale and your 6 micro and 9 bloom comes in at 825ppm or about 1.1 EC, great for starting out plants in flower, IMO.
 
hellraizer30

hellraizer30

Rebel From The North
mas3372 said:
I proportionally increased the micro and bloom to achieve 900 and the plants are doing well with that in veg. plants 3 inches to 12 inches.

this is the meter i bought...couldn't find what in the manual or description what scale it is....http://www.amazon.com/gp/product/B000VTQM70/ref=oss_product
Click to expand...
is your pen reading .5 or .7 ? cuz at .5 it will read the 900ppm and at .7 it wont my pens got both so I can cross reference it
 
L

lightningkid

Member
mas3372 said:
Pen only reads a ppm...have no idea what .5 or .7 mean
Click to expand...
COPY AND PASTE FROM ANOTHER THREAD:

Difference is what chemical it is basing it's PPM 'guess' off of. All PPM meters are EC meters that convert. I prefer to use the NaCL EC setting on mine, and then convert to ppm (.5) or ppm (.7) depending on situation using the scale below. The only difference between the 3 ec settings are the temperature compensation curves. I choose

EC NaCl.

(EC(mS))—(PPM.5)—(PPM.7)—(CF)
.4———200————-280———–4—–seedling/ rooted clones
.6———300————-420———–6—–
.8———400————-560———–8—–veg
1.0——–500————-700———-10
1.2——–600————-840———-12
1.4——–700————-980———-14
1.6——–800————-1120———16—–aggressive
1.8——–900————-1260———18
2.0——–1000————1400———20—–super aggressive
2.2——–1100————1540———22
2.4——–1200————1680———24

So if it reads 956, your ec is .956.... if it reads 104 and the x10 symbol is blinking, this is 1.04 EC, make sense?

Reason I prefer EC is it never changes. Too often people throw around PPM measurements and never note if its the .5 or .7 scale. As you can see this makes a big difference... at 1EC, the (.5)ppm is 500, but the (.7)pmm is 700. If the person doesn't mention what scale, we really have no clue which to choose.

With this meter you can measure EC (NaCL, 442, KCL) or PPM (NaCl & KCL are .5 scales) and (442 is a .7 scale)
 
mas3372

mas3372

Active Member
lightningkid said:
COPY AND PASTE FROM ANOTHER THREAD:

Difference is what chemical it is basing it's PPM 'guess' off of. All PPM meters are EC meters that convert. I prefer to use the NaCL EC setting on mine, and then convert to ppm (.5) or ppm (.7) depending on situation using the scale below. The only difference between the 3 ec settings are the temperature compensation curves. I choose

EC NaCl.

(EC(mS))—(PPM.5)—(PPM.7)—(CF)
.4———200————-280———–4—–seedling/ rooted clones
.6———300————-420———–6—–
.8———400————-560———–8—–veg
1.0——–500————-700———-10
1.2——–600————-840———-12
1.4——–700————-980———-14
1.6——–800————-1120———16—–aggressive
1.8——–900————-1260———18
2.0——–1000————1400———20—–super aggressive
2.2——–1100————1540———22
2.4——–1200————1680———24

So if it reads 956, your ec is .956.... if it reads 104 and the x10 symbol is blinking, this is 1.04 EC, make sense?

Reason I prefer EC is it never changes. Too often people throw around PPM measurements and never note if its the .5 or .7 scale. As you can see this makes a big difference... at 1EC, the (.5)ppm is 500, but the (.7)pmm is 700. If the person doesn't mention what scale, we really have no clue which to choose.

With this meter you can measure EC (NaCL, 442, KCL) or PPM (NaCl & KCL are .5 scales) and (442 is a .7 scale)
Click to expand...
Holy Motrin!!! I got ya now, so I just need to find out if my meter is a .5 or .7...but I looked and can't figure that out. If its a .5 then I it seems I am right on but if its a .7 then I am a little low. I'm guessing its a .5 since I got in the 700s with the lucas as it is, under a .7 it would have been the 980 which is what it is supposed to be. I did increase to achieve 950 or so, so now I am actually feeding around 1300....The plants aren't burning, actually holding up nice and I'm getting a 1/2 inch a day growth. Should I back off?
 
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