HyDroHawg

The lesson here is to help you measure and understand the readings you obtain from pH and EC meters...

Let me first explain what pH & EC mean, and what effects them...
pH stands for Potential Hydrogen and is a measure of the concentration of hydrogen ions within a solution like water. pH is measured on a scale of 0 to 14 with 0 being acid, 7 is neutral and 14 is alkaline. A substance that when added to water increases the hydrogen ion concentration will cause the pH level to drop. This is known as a acid. A substance that reduces the concentration on hydrogen ions and causes the pH to rise is known a base. There are also some substances that can enable the solution to resist pH changes when an acid or base is added. These are known as buffers. Buffers are very important in helping organisms maintain a relatively constant pH and they are also used to calibrate your pH meter occasionally.

If the pH of your nutrient solution is too high (alkaline) or too low (acidic), it can restrict the uptake of nutrients through the roots of your plants. Many different variables such as evaporation, amount of light and temperature can affect pH levels. Most plants can accept a pH range of between 5 and 7. Any extremes either side of that range will cause the plants to be blocked from certain nutrients. In low light, plants take up more potassium and phosphorus from the nutrient solution so the acidity increases (pH drops). In strong intense light, plants take up more nitrogen from the solution so the acidity decreases (pH rises). Any extremes of pH can also result in precipitation of certain blocked nutrients.

For plant roots to be able to absorb nutrients, the nutrients must be dissolved in a solution. The process of precipitation (the reverse of dissolving) results in the formation of solids in the nutrient solution, making the nutrients unavailable to the plants. Precipitation can also take the form of an almost invisible film of an oily look on the surface of your water.

EC stands for Electrical Conductivity and is a measure of the strength of the nutrient solution. The higher the conductivity, the more dissolved solids there are in the solution. EC is just one format of measuring the nutrients. It can also be measured in PPM (Parts Per Million), and TDS (Total Dissolved Solids). EC is the standard these days and is used in Canada, Europe, and most other places...

Plants at different stages of growth need different amounts of food in their solution. Delicate plants like cuttings and seedlings requre the EC to be quite low so as to avoid fertilizer burn from over-feeding. As the plant gets older the food concentration can be increased (EC raised) so the plants have access to more nutrients in the water. Low conductivity at this point or low strength nutrient solutions will result in nutritional deficiencies and slow growth rates of your plants. EC can be affected by many variables too. Evaporation, temperature and ventilation are all factors that affect the EC level in your solution aswell...

<edit> I hope this helps out a little... I found these little tidbits browsin' the www I figured I'd share the knowledge... L8R.

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unregistered190

i got a good grasp on the ph thing already i think....but nice job of explaining it.

with the EC i am a little confused though

reason i ask......is i purchased a combo meter...does ph/ppm disolved solids...and thought that would be all i need. then ran across a grow journal that listed both ppm and ec. so got wondering if they were/were not proportional to each other

i am off to the search function to try to find out.....got me wondering now.

take care - 190

jamesgang

... Thanks for sharing...

JG

They are the same. Just that darn metric thing versus u.s standardsl. I use ppm although my meter can do both.

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THE MONSTERMAN RETURNS...


The JamesGang

HyDroHawg

I actually use both measurements in my journal... ppm being what Americans generally use, and the Euro-fellas use EC. Both measure the same thing.

Thanks JG... I figured it'll help out da newbies on the subject...

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unregistered190

was still surfing for the answer when u replied.......read a couple of debates of ec vs tds. think i would want to measure in ec, seems to be the prefered measurement.

guess its time for us americans to catch up w/ the rest of the world ....hmmmmm lets see......12 inches in a foot....3 foot in a yard.....OR 10mm make a cm......100 cm make a meter...and a 1000 m make a km....

i like it nice and simple

later - 190

just seen your reply jg ....thanks! was replying when you answered i guess.....time lag, haha

HyDroHawg

I catch myself using the EC measurement alot though... Seems alot more universal... It just seems that when I read my Truncheon meter, my eye catches the meter reading the EC #, and that's the one I pay attention to. The ppm #'s are too high for me to remember... 4 digits vs 2... Like I said, it doesn't make a diff... It's all the same measurement...

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fl0w_gr0w

what is the result of low ph ?
what would be a good physical characteristic of a plant when it doesn't get food.

malibu

EC makes more sense, as that IS what you are really measuring - the electroconductivity . . .

more stuff if the water - more solutes - the higher the electroconductivity

it DOES matter what the solutes are -
- but the ppm conversion is just taking the EC number and multiplying it by a factor estimating what the ions in solution might be - the meter really doesn't know what the factor is, and some meters you could change the factor - but that is just multiplying the EC value measured anyway.

HyDroHawg

It would be a very rare occasion if your H20's pH was lower than 7; being neutral. Tap water generally comes out with a higher pH due the chlorination/flouride additives the local counties/or what not have put in to make your tap water safe to drink... Low pH's wouldn't allow certain elements to be taken up by the plant.

<edit> Please refer to Stoneys pH uptake chart here... That'll help you out by showing whats taken up when and where...

Droopy leaves, Lighter Shade of Green leaves, would be signs of under-nutrition. I really havn't heard of anyones pH being too low to start with... It's usually way too high.

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malibu

Well good questions for a first post there flowgrow -

Welcome to the forum . . .

hydrohawg must have misunderstood ya tho -

low pH could of course occur in your nutrient solution -

if hydrohawg has any doubt about that he should get his hands on some nitric acid and drip it into the water ( ok don't REALLY try that )

point is any acid added into pure water will dissociate and if net effect is to add hydrogen ions more than the H20 (pure) then it will be an acid

pH is negative logarithm of the hydrogen ion concentration - so . . .

more hydrogen ions means that the pH (negative log) is less than 7.0

some nutrients will dissociate so that there are more hydrogen ions in solution and you can get pH of say 6.0 . . .

do alot of searches, and ask good questions - there's alot of good people here.

doesn't get food ? whatthya think ?

plants make sugars from CO2 and H2O , along with light of the proper frequency (callled photosynthesis) but they need their nutrients to make it go faster -
with love and care you get this sticky resin called THC, which has medicinal and recreational uses . . .

Good luck.