Runoff pH and EC

Strain; Euphoria seed
Soil in pots, Coco/Perlite 4:3 mix.
System type?
PH of runoff 6.6
What is strength of nutrient mix? EC 1.22
Indoor 60cm x 60cm tent
Light system, size? 125W CFL
Temps; Day 26-28C, Night 25-27C
Humidity; Day 45-55%, Night 45-55%
Ventilation system; Yes, 125mm, 190m³/hr, adjustable fan speed.
AC, Humidifier. Co2; No
This is my first time growing and I need some information, thank you.
I live in Spain and the temperatures reach 34 to 38 deg C in the afternoon. It doesn’t fall below 22 at night (July August). Humidity is usually low. My air-con in the lounge keeps my grow room (close by) down to an acceptable level. I have read extensively on line but cannot find information on runoff data. My plant is now 5 weeks old and 9 inches high (should this be taller? – 2 gall smart pot).
Last feed I added 2 litres with pH of 5.5 and EC 1.22. The runoff (0.5 litres) had pH of 6.6 and EC 2.47. I feed 2 times and water flush the 3rd, approx. every 2 days. I recently bought a Blumat soil moisture sensor to indicate when it needs water, excellent, it stops me from overwatering. At my last flush the runoff pH was 6.2 and EC 2.42. The runoff EC seems high to me – or is it? Am I overfeeding? How do I adjust EC from the runoff figures? What is the relationship? Even though the plant looks healthy now – I did have some leaf tips turn brown after re-potting 2 weeks ago – seems to have recovered now. I intend to change to a HPS 250W for flowering. Any comments or suggestions would be appreciated. Thanks.

I think you’re water her whit wrong ph… For soil needs to be around 6.5-6.8…but I will let the big guys to give you a good answer on that… I will put some pictures, maybe you see what is wrong with your plant Nutrient_Chart2


It looks like you are doing soil less. If so, your ph is even more off and this will be a problem if you don’t resolve it now. Verify your means of measuring ph, for soil, water in should be 6.5 after nutes are added and abut 6.2 out. Soil less should be 6.0 ph after nutes, not sure of runoff.

Sorry, I don’t know what you are asking about EC.

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Thank you for the response. However, the growing media I am using is Coco/Perlite 4:3 ratio, so the pH is OK. I usually aim for pH5.7
I read in various place the range for feeding is pH 5.5 to 6.3 for coco.
Another quote from “Rollitup” “pH and Nutes for coco: We have one friend who keeps his ph at 5.2. Ours is about 5.5. The safe range appears to be 5.4- 6.2 . IMO 6.2 is the very high end, and you see better results under 6.0”
I know everyone has different ideas on what’s best - I’m just a beginner, and trying not to make too many mistakes.

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Yeah, I would target in at 6.0 (I am now) and around 5.8 out. 5.4 is too low IMO.

That’s interesting - pH lower in your runoff? My runoff is always higher - today’s was 6.5 and it was a very weak solution.
What about your EC? That’s my most concern. My filtered water is EC 0.6. I think that is high. What’s in the water to make it so? I need to add only 0.6 of nutrients to get 1.2, so am I under-feeding? The plant looks healthy - at the moment!
I regularly calibrate my meters.

No idea what EC is. TDS during veg should be in the 1,500 ppm range. Give or take.

The ph higher at runoff may be a problem. Why not bring in one of the power hitters? @garrigan62, @latewood, any ideas?


I’m out in the car paying bill’s lol
I’ll get you all set shortly my friend. Ok


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this should help you to beetter understand it


PPM–EC conversion Chart

Re-printed with Permission from Jorge Cervantes;

EC Hanna Eutech Truncheon CF
ms/cm 0.5 ppm 0.64 ppm 0.70 ppm 0
0.1 50 ppm 64 ppm 70 ppm 1
0.2 100 ppm 128 ppm 140 ppm 2
0.3 150 ppm 192 ppm 210 ppm 3
0.4 200 ppm 256 ppm 280 ppm 4
0.5 250 ppm 320 ppm 350 ppm 5
0.6 300 ppm 384 ppm 420 ppm 6
0.7 350 ppm 448 ppm 490 ppm 7
0.8 400 ppm 512 ppm 560 ppm 8
0.9 450 ppm 576 ppm 630 ppm 9
1.0 500 ppm 640 ppm 700 ppm 10
1.1 550 ppm 704 ppm 770 ppm 11
1.2 600 ppm 768 ppm 840 ppm 12
1.3 650 ppm 832 ppm 910 ppm 13
1.4 700 ppm 896 ppm 980 ppm 14
1.5 750 ppm 960 ppm 1050 ppm 15
1.6 800 ppm 1024 ppm 1120 ppm 16
1.7 850 ppm 1088 ppm 1190 ppm 17
1.8 900 ppm 1152 ppm 1260 ppm 18
1.9 950 ppm 1216 ppm 1330 ppm 19
2.0 1000 ppm 1280 ppm 1400 ppm 20
2.1 1050 ppm 1334 ppm 1470 ppm 21
2.2 1100 ppm 1408 ppm 1540 ppm 22
2.3 1150 ppm 1472 ppm 1610 ppm 23
2.4 1200 ppm 1536 ppm 1680 ppm 24
2.5 1250 ppm 1600 ppm 1750 ppm 25
2.6 1300 ppm 1664 ppm 1820 ppm 26
2.7 1350 ppm 1728 ppm 1890 ppm 27
2.8 1400 ppm 1792 ppm 1960 ppm 28
2.9 1450 ppm 1856 ppm 2030 ppm 29
3.0 1500 ppm 1920 ppm 2100 ppm 30
3.1 1550 ppm 1984 ppm 2170 ppm 31
3.2 1600 ppm 2048 ppm 2240 ppm 32

There are three conversion factors which various manufacturers use for displaying ppm’s…

USA 1 ms/cm (EC 1.0 or CF 10) = 500 ppm
European 1 ms/cm (EC 1.0 or CF 10) = 640 ppm
Australian 1 ms/cm (EC 1.0 or CF 10) = 700 ppm

For example,

Hanna, Milwaukee 1 ms/cm (EC 1.0 or CF 10) = 500 ppm
Eutech 1 ms/cm (EC 1.0 or CF 10) = 640 ppm
Truncheon 1 ms/cm (EC 1.0 or CF 10) = 700 ppm


Fertilizers PPM

To discover the ppm of your fertilizer mix, you will require being able to gauge grams and liters. Come across at the nutrient 3 numbers written on the side of a fertilizer package, these are the percentage substances of the nutrients in the fertilizer. Each one gram of that fertilizer in to one liter of water, this will give 10 ppm per percentage point of the given nutrient.

Example a 20-20-20 nutrient gives (10 ppm x 20) or 200 ppm of every nutrient for each gram in a one liter of water.


Grams of fertilizer per liter = A/B
A = your desired ppm
B = 10 ppm x the % of nutrient in mix or your ppm = C x B
B = 10 ppm x the % of nutrient in mix
C = gram of fertilizer per litter.

So to make create a 200 ppm to 100 ppm to 200 ppm NPK mix utilizing a 13-0-44 ratio of potassium nitrate, a 12-62-0 ratio of monoamonium phosphate, and a 33-0-0 ratio of ammonium nitrate you would work in reverse from your single P and K basis (it makes it the simplest in this case), and create up the N at the finish. I have rounded values to the nearest 0.1 g for the following. You would utilize 0.5 g of potassium nitrate about 200 ppm/910ppm x 44k and 0.2 g of mono-ammonium phosphate at about 100ppm/(10ppm x 62P) in one liter.

Fertilizers PPM

This would provide you 89 ppm N (10ppm x 13N x 0.5g + 10 ppm x 12 N X0.3g), 124 ppm P (10ppm x 62 P x 0.2), and 220 ppm k (10ppm x 44k 0.5g). 111 ppm is necessary to elevate the N to 200 ppm level, so we can utilize 0.3g of the ammonium nitrate (111 ppm/ (10 ppm x33N) to take us up to complete. The concrete mixture would give away a 188 ppm N, 124 ppm P, 220 ppm K mixture in one liter of water.

To obtain more accuracy, you require combining big batch or getting an improved range. You would require to make 10 liter set of the over with a range that is only precise to the gram. If you blend your own fertilizer, you can regulate your N basis to meet up your ph requirements, rather than relying on adding acid or base, which is good. This works for formulating hydro mixes, as well as for us soil farmers.


I used to use 1500 ppm but, that is too strong for a lot of genetics. Makes stems woody and therefore hard to clone and makes it harder to find that great taste we all are looking for. I never run over 1200 anymore (indoors). I do get there in week 6-8 when we boost the P-K in the mix.

600-880 in early veg, and up to 800-1000 in late veg. Flowering at 1200-1300 with P-K boost up to 1500 in week 6.7.8 r 2 weeks before the final 2 week finish.

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Thank you all for the replies. I do understand ppm’s are preferable in the US, but I find it complicated as there are different scales, Hanna Eutech etc. Also, a TDS meter is just a EC meter which converts the readout to ppm. So I am feeding a weaker solution in order to reduce the runoff EC. Yeah, EC rules.

Ok. So r u saying that high PPM thru out grow could or will affect TASTE??? Mine has been probably averaging 1300ppm each change. Would I expect off flavour??

There is no difference between TDS and EC except that they are measured in different ways. Either way; We are finding better taste using weaker solutions these days.

As far as taste, it depends on which nutrient line you use and whether or not and how long you flush. I am keeping my ppm (TDS), at 1200 or lower in flower.

PH has no affect on taste other than the fact that if you allow ph to get too far off, it affects, the balance of the different minerals in the solution.

Happy growing, lw


Good grief. I’m using GH FLORA TRIO and had PPM up to 1700 and some I think last grow.

In week 6-7, 1700 ppm could be OK, but, the week after and towards flushing you definitely want to do away with “grow” part. I always used ) 0-1-2 in flower.

However; If I grew with 3 part still, I would limit ppm to around 1200 as mentioned.

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That’s heaps different to what I did. Could you give me some suggestions as to how I would feed indicas for an extended veg. Possibly 6 months maybe more

This is getting off topic. Who started this topic?

Depends on why you want to veg an Indica for 6 months; What size of space you have; And, What head room you have.