Best pH And EC Value

Adam Parsons

Cannabis Journalist & Staff Writer at Zamnesia

Adam Parsons

June 13, 2019

WHAT IS pH?

“Potentia hydrogenii” or pH is the logarithmic measurement scale for the acidity to basicity concentration of a solution. What pH means to the scientist is similar to the cannabis grower’s interpretation. However, it is in the application of this understanding where the differences emerge.

In the lab, pH is used to quantify the ratio of negatively and positively charged ions in a liquid. While in the grow op the pH is important when it comes to watering and feeding plants. Moreover, it is of paramount importance to also monitor the pH of the growing medium and adjust as required.

The pH scale ranges from 0-14, running from acid to base. A pH of 7 is considered neutral, below is more acidic and above is more alkaline. Just like the Richter scale used to measure earthquakes the pH scale multiples each point by a factor of 10, i.e. pH 9.0 is ten times more alkaline than 8.0.

• pH 14: caustic soda solution (1 mol/l)
• pH 13: caustic soda solution (0.1 mol/l)
• pH 11.5: domestic ammonia
• pH 10.5: soapsuds
• pH 8.5: seawater, intestinal fluid
• pH 7.4: human blood
• pH 7: pure water (neutral)
• pH 6.7: milk
• pH 6: rain water
• pH 5: lightly acid rain
• pH 4.5: acid rain, tomato juice
• pH 3: domestic vinegar
• pH 2.5: cola
• pH 2: stomach acid, lemon juice
• pH 1: sulphuric acid (battery acid)
• pH 0: hydrochloric acid (1 mol/l)

WHAT IS EC?

This acronym stands for electrical conductivity. For the cannabis cultivator and especially hydroponics growers EC measurement is essential to applying nutrients correctly.

In the lab, EC is how the potential to conduct electricity of materials is measured. In contrast, the only material and liquid the grower is interested in is the growing medium and water.

EC measurement is how the grower gets the most accurate reading of nutrients in feed solutions and the growing medium itself. Getting feeding perfectly dialled in is a key objective of all growers regardless of how the grow op is set up.

The common method of counting the ions or salts in water is in PPM terms or part per million. Although this is the North American standard most weed growers around the world are most familiar with the PPM to EC conversion charts.

Don’t worry if you’re not familiar with conversion right now, just Google PPM to EC conversion chart and download one for future reference. Essentially the conversion of a PPM value to EC helps a grower gauge the nutes dosage.

WHAT ARE THE BEST pH AND EC VALUES?

The optimal pH and EC values for cannabis cultivation are contingent upon three factors, the growing substrate, nutrients and water. For soil growers a pH of 6.0-6.5 is perfect.

While hydro and coco growers should aim for 5.8pH, or at least maintain pH around 5.5-6.1. Soil is a more forgiving medium and acts as a buffer for the root zone. In contrast, hydro systems are far less forgiving and pH must be perfect every time.

EC values are often listed on the bag exterior of high-quality cannabis cultivation substrates. Soils usually give a breakdown of each nutrient % and an estimate how many weeks fertiliser the soil can provide young cannabis plants.

The perfect EC value is different for each cannabis strain. In general heavy-feeding indicas prefer higher EC values of 2.5+, while some light-feeding sativas prefer a low EC of 1.0 or they will become over fertilised.

Water has an EC value of 0 and usually is pH neutral so 7.0 pH value. Specialist soil is usually around 6.0 pH and hydro clay pebbles and perlite are neutral sterile mediums.

Hydroponics obviously requires more fine tuning than low maintenance organic soil cultivation. Rockwool cubes should be pre-soaked in 5.8pH solution before planting seeds or cuttings in them.

The diligent cannabis grower must be careful to monitor nutrient doses and evaluate pH and EC for every feeding. Fluctuations in the pH and EC are to be avoided.

Water pH must be consistent and EC must be gradually increased as plants behaviour dictates. Runoff water must also be evaluated weekly to avoid salt build ups, this is so important for hydro growers.

Over-fertilisation is one of the most common problems for hydroponics cultivators and will be discussed in greater detail in the hydro section.

However, it suffices to say that the problem usually stems from the grower adding far too many PPM’s of nutes resulting in an excessively high EC.

HOW TO MEASURE pH AND EC

Today there are plenty of handy tools to help the cannabis grower monitor pH and EC values. The best advice is to pick up a pH and EC measuring pen. For a small investment, typically under €100, the grower can purchase an all-in-one digital device with calibration fluid included.

Old school pH charts with little vials to shake and hold up and compare work too as do soil tester kits. For the outdoor grower, the simple inexpensive measurement alternatives are fine. But hydroponics demands precision, so don’t get cheap with it comes to pH and EC measurement.

HOW TO CONTROL pH AND EC

Controlling pH and EC used to be quite challenging before the recent explosion of online grow shops and boom in canna-business e-commerce. Innovative 21st-century ganjapreneurs have devised really clever solutions to pH and EC control.

The advent of “pH Perfect” nutrients by Advanced Nutrients and medium specific product lines takes all the hassle out of dialling in feeding. In fact, this technology even renders pH and EC pens unnecessary for most home growers using these fertilisers.

For the grower that craves simplicity and can afford premium-priced nutes, this is the simple solution to pH and EC control.

HOW TO CORRECT pH AND EC

These days pH correction is a quick fix. Most organic cannabis nutrients like the BioBizz line of liquid fertilisers generally lower the pH of neutral water to around 6.0 pH. Should pH dip too low adding 1ml per 5l of water, liquid silicon will in most cases increase pH by 1 or 2 points to correct.

However, should pH swing upwards towards alkaline to 8.0 or above a few ml of malt vinegar can be added per 5l of water to drop it down. Of course, pH up and pH down solutions are widely available too. These come in specific vegetative and bloom stage formulations and require only a few drops per litre to balance pH.

EC correction is also relatively uncomplicated. In general, the best first step to solving this problem is to start with a flush of pure water, most of the time the cause is too high EC from excessive nute doses.

Post flush adjusts feeding and makes sure to measure the EC. Usually, a light feed with plenty of supplements like enzymes and carbs is a good recovery feed to get the root zone and the whole grow show back on track.