Soil analysis, water analysis and nutrient solution analysis: Why your grow needs more than pH and EC

Pale leaves, spots, slowed development or a plant that fails to progress properly despite seemingly suitable feeding: In situations like these, the guessing game often begins.

Is there a calcium deficiency? Is there too little magnesium? Does something need to be added? Is the pH value incorrect? Or could the problem lie in the irrigation water?

The honest answer is: A visible deficiency symptom is not yet a diagnosis.

The plant merely indicates that something within its system is not functioning optimally. However, it does not automatically show where the cause lies. The root zone is not supplied by a single input alone. Its conditions result from the interaction of:

• Living Soil or substrate
• irrigation water
• available nutrients
• biological and chemical availability
• root zone and moisture management
• a ready-mixed nutrient solution, if applicable

That is precisely why it is often not enough to look only at a leaf symptom, the pH value or an EC reading.

A laboratory value does not replace good observation. However, it makes cause analysis considerably more reliable. Instead of reacting immediately, you can check which assumptions are supported by measured values—and which are not.

Soil, water and nutrient solution form a shared system

In cultivation, soil, water and nutrient supply are often considered separately. In practice, however, they constantly influence one another.

The substrate stores, buffers and changes conditions in the root zone. The irrigation water introduces new minerals and salts into the system with every watering. A nutrient solution, in turn, not only adds nutrients but also changes the EC / electrical conductivity, the ratio of individual elements and, in some cases, the pH value.

The pH value influences how nutrients behave within a system and how well they can remain available to plants. The EC value, by contrast, indicates electrical conductivity and therefore the sum of dissolved, conductive components—but not which individual substances cause this value. In soilless systems, part of the natural buffering capacity that soil or an organic substrate can provide is also absent.

This means:

A suitable EC value does not prove a balanced nutrient solution. A suitable pH value does not prove sufficient availability. And a visible deficiency does not prove that the substrate actually contains too little of the suspected nutrient.

Why deficiency symptoms alone do not provide a reliable diagnosis

Similar symptoms can result from different causes.

An apparent nutrient deficiency may, for example, actually be caused by insufficient supply. But it can also occur when:

• the nutrient in question is present but poorly available under the given conditions
• the pH range is unfavorable
• the salt content is elevated
• other nutrients are present in an unfavorable ratio
• the irrigation water regularly introduces undesirable substances
• the root zone is too wet, too dry or structurally impaired
• a ready-mixed nutrient solution deviates from the intended formulation
• environmental or root problems limit uptake

Anyone who acts exclusively on the visible symptom therefore risks working past the actual problem.

Reflexively adding more inputs is particularly critical. If there is no actual undersupply, this can intensify an imbalance that already exists.

An analysis does not automatically answer every biological question. However, it can clarify whether the values examined fit your previous assumption. An unremarkable result is therefore valuable as well: It redirects further troubleshooting away from the nutrients examined and toward other possible causes.

1. Soil analysis: What is your Living Soil actually providing?

Living Soil is not a static bag of soil. It is a system that changes with every watering, every addition, every cycle and every form of biological activity.

With reused substrates in particular, it is therefore crucial not only to know what was originally mixed in. What matters is the current condition.

A nutrient analysis of the soil or a chemical examination of the Living Soil can help narrow down questions such as:

• Are the nutrients examined low, sufficient or conspicuously high?
• Is the salt content elevated?
• Is the pH value within a plausible range?
• Is adding more actually useful?
• Which areas should be considered for a re-amendment?
• Can the substrate continue to be used?
• Could the suspected cause instead lie in the water?

Which values are examined in the Living Soil Check?

The CannaSelection Living Soil Check is based on an extended chemical substrate analysis. The following are analyzed:

This scope corresponds to an extended basic horticultural analysis for substrates.

When is a soil sample particularly useful?

A soil analysis is relevant not only before a planned re-amendment. It is particularly useful when:

• visible deficiency symptoms occur
• plants stagnate despite previous feeding
• symptoms persist after adding more
• the substrate has been reused several times
• different raw materials and inputs have been combined
• you want to rule out overfeeding
• the performance of the Living Soil varies from cycle to cycle
• you need reliable values before the next use

What a chemical soil analysis does not measure

A chemical substrate analysis is not a complete microbiome analysis.

It does not automatically show:

• how high the microbial biomass is
• which microorganisms are present
• what the ratio of fungi to bacteria looks like
• how quickly organically bound nutrients will be released in the future
• how actively soil life is functioning under the current cultivation conditions

This is not a weakness of the analysis, but an important technical distinction.

The chemical analysis answers the question: Which of the values examined are measurable in the submitted sample, and how can they be classified in the context of the system?

It therefore provides an important part of the diagnosis—but not the complete biological picture.

CannaSelection analysis process:
Have your Living Soil or organic substrate analyzed, receive the laboratory values and classify them professionally together with your information.

2. Irrigation water analysis: Your water always contributes

Irrigation water is often assessed using only two values: pH and EC.

Both values are important. However, they are not sufficient for a complete assessment.

The EC value shows how strongly the water conducts electricity. It does not say whether this conductivity is primarily caused by calcium, magnesium, sodium, chloride, sulfate or other dissolved substances.

Two water sources can therefore have a similar EC value and still create completely different conditions for a cultivation system.

The pH value alone also does not describe how strongly water is buffered against a change in pH. Carbonate hardness or bicarbonate, among other factors, is relevant for this classification. When interpreting irrigation water, substances such as sodium and chloride must also be considered, as they can accumulate in the system with repeated use.

Which values are examined in the irrigation water analysis?

The CannaSelection chemical irrigation water analysis includes 13 defined values:

• pH value
• total hardness
• carbonate hardness
• electrical conductivity
• chloride
• sulfate
• nitrate nitrogen
• ammonium nitrogen
• iron
• sodium
• potassium
• calcium
• magnesium

The defined scope corresponds to a horticultural irrigation water analysis.

These values enable a much more comprehensive assessment than a purely pH- or EC-based measurement.

For example, it can be determined:

• how much calcium and magnesium the water already contains
• whether the ratio of both elements should be taken into account
• whether sodium or chloride are conspicuous
• how strongly the water is mineralized
• whether water treatment or mixing could be useful
• whether additional calcium or magnesium products are needed at all
• whether the water may play a role in recurring irregularities

CalMag Calculator and water location search: The first digital check

Not every water-related question requires a new laboratory analysis immediately.

If you have current and complete water values, you can first use the CannaSelection CalMag Calculator & Water Values.

The tool offers two options:

1. Search for a water location by ZIP code or town

With the location search, you can check whether a water profile is already available for your area. The result leads to a suitable location page with stored water values, a system classification, an assessment and information about the data basis.

This is particularly helpful for an initial orientation.

However, it is important to remember that supplier data may refer to a larger supply area. In addition, household plumbing, filters, water softeners, reverse osmosis systems, mixtures or storage tanks may cause the water you actually use to differ from the published information.

2. Enter your own water values

Alternatively, you can use your own values from a laboratory report or an analysis provided by your water supplier.

The calculator is primarily designed to evaluate:

• calcium
• magnesium
• bicarbonate
• sodium

Additional values that can be entered include:

• pH value
• water hardness
• electrical conductivity

The medium, setup, phase and desired calcium-to-magnesium ratio can also be taken into account. Based on this information, the tool creates a system-specific assessment with possible corrective steps.

When is the location search sufficient, and when is laboratory analysis better?

The location search is a useful starting point when:

• you use tap water
• current supplier data is available
• the water is not further treated
• you initially need basic orientation

An individual irrigation water analysis is the better choice when:

• you use well water
• rainwater or tank water is used
• a water softener or filter system is installed upstream
• you use reverse osmosis water or blended water
• the water source changes seasonally
• you want to know what actually reaches your point of use
• recurring deficiency symptoms or deposits occur
• the published water values are incomplete or outdated

The calculator and laboratory analysis are therefore not competing options.

The calculator helps you assess existing data more quickly and try out different strategies. Laboratory analysis provides the data basis when your actual water sample is decisive.

CannaSelection analysis process:
First check the water profile or your own values in the CalMag Calculator. If the water source is unknown, treated or problematic, have the sample actually used analyzed.

3. Nutrient solution analysis: It is not the schedule that matters, but what is in the tank

A feeding schedule describes which products should be used and in what quantities.

However, it does not prove that the ready-mixed nutrient solution exactly matches this theoretical composition.

The actual result can be influenced by:

• the composition of the source water
• dosing deviations
• combining products from several manufacturers
• additional calcium and magnesium products
• trace elements and other additives
• the order of addition
• pH corrections
• precipitation
• deposits
• incomplete mixing
• the age and temperature of the solution

In Hydro, coco and other soilless systems in particular, the nutrient solution is directly responsible for supplying the root zone. While soil can buffer some fluctuations, pH, EC and composition must be controlled much more directly in soilless systems. Technical information on hydroponics also indicates that nutrient ratios within a reservoir can shift over time even when the EC value still appears plausible.

Why pH and EC alone cannot replace a nutrient analysis

The EC value is a cumulative value.

It does not show:

• how much nitrogen is actually present
• whether nitrogen is present mainly as nitrate or ammonium
• whether calcium and magnesium have been appropriately accounted for
• whether sodium or chloride contribute to the EC
• whether trace elements are missing or conspicuous
• whether phosphate is present in the expected range

A nutrient solution can therefore show a suitable EC value and still deviate from the intended formulation.

Which values are examined in the nutrient solution check?

The nutrient solution check includes the 13 parameters of the irrigation water analysis and adds five further nutrient values.

A total of 18 values are analyzed:

• pH value
• total hardness
• carbonate hardness
• electrical conductivity
• chloride
• sulfate
• nitrate nitrogen
• ammonium nitrogen
• iron
• sodium
• potassium
• calcium
• magnesium
• copper
• zinc
• manganese
• boron
• phosphate, stated as P₂O₅

The scope corresponds to an extended horticultural water and nutrient solution analysis.

Which sample is analyzed?

The undiluted product is not analyzed, nor is an individual concentrate.

The sample should correspond exactly to the fully prepared, ready-to-use nutrient solution that is actually used.

This includes:

• the regular source water
• all base products
• all regularly used additives
• the usual dosage
• the usual order of addition
• the regular pH adjustment

Only in this way does the analysis result reflect the solution that actually reaches the system.

CannaSelection analysis process:
Send in fully prepared nutrient solution, have its composition checked and assess the formulation based on the actual measured values.

Which analysis methods are used?

CannaSelection uses different, clearly defined analysis profiles for the three areas.

Extended chemical substrate analysis

The Living Soil Check examines the chemical and physical properties of the submitted substrate sample. These include pH value, salt content, soluble nitrogen, phosphate, potassium, calcium, magnesium and bulk density.

Chemical irrigation water analysis

The irrigation water analysis examines the actual water sample submitted for hardness, conductivity, relevant anions and selected macro- and trace elements.

Extended nutrient solution analysis

The nutrient solution analysis supplements the scope of the irrigation water analysis with additional trace elements and phosphate. This allows the fully prepared solution to be assessed in greater detail.

The analyses are performed by a partner laboratory specializing in horticultural analytics, using established laboratory and VDLUFA methods. The laboratory report contains the measured values. CannaSelection is responsible for the subsequent classification, system assessment and derivation of recommendations.

A laboratory report and its interpretation are not the same thing

A laboratory measures a sample.

However, it does not automatically know:

• your complete setup
• the previous use of the substrate
• your water source and water treatment
• all products used
• the order and frequency of applications
• the development of visible symptoms
• your goals for future use

That is precisely why it is often not enough simply to forward a laboratory report.

At CannaSelection, the measured values are considered together with the information from the sample submission form. Depending on the analysis, this may include:

• substrate type and substrate age
• previous usage cycles
• pot or bed volume
• inputs used
• time of the last application
• water source
• filter or reverse osmosis system
• self-measured pH and EC value
• composition of the nutrient solution
• existing symptoms
• specific question

This forms the basis for a prioritized recommendation.

A meaningful recommendation does not automatically mean adding more. The result may equally be:

• not adding anything initially
• reducing individual inputs
• checking the water more closely
• adjusting the nutrient solution
• mixing or treating the water source
• shifting further troubleshooting to the root zone, moisture or environmental conditions

Which approach is right for your situation?

This classification is not a rigid diagnostic protocol. However, it helps you begin the analysis where the greatest uncertainty exists.

Sampling determines the reliability of the results

The best laboratory method cannot correct an unsuitable sample.

For Living Soil and substrate

A single handful taken from a random spot often does not adequately represent a pot or bed.

A composite sample from several comparable areas of the rooted zone is advisable. Containers with different structures, treatments or watering should not be mixed together.

For irrigation water

The sample should be taken exactly where the water is actually used.

If you use a reverse osmosis system, filter or water softener, take the sample downstream of that system. For tank water, the sample should come from the regularly used draw-off area.

For nutrient solution

The sample must be fully prepared, thoroughly mixed and ready for use.

Concentrates, individual components and stock solutions do not represent what ultimately reaches the roots.

The CannaSelection product pages contain specific sampling and submission instructions for each analysis. A special test kit is currently not required.

This is how an analysis at CannaSelection works

1. Select the right analysis

You decide whether Living Soil, irrigation water or a fully prepared nutrient solution should be analyzed. An overview of our analyses can be found >here<

2. Take the sample according to the instructions

After ordering, you will receive the sampling instructions, sample submission form, order number and shipping address.

3. Analysis in the partner laboratory

The sample is checked, assigned and forwarded to the specialized partner laboratory.

4. Evaluation by CannaSelection

After the laboratory analysis, the values are assessed together with your information about the setup, previous feeding and specific question.

5. Report and recommendations

You will receive the laboratory report, professional assessment and specific next steps digitally. Questions about the evaluation provided are welcome.

For the analyses offered, processing generally takes around two to three weeks from receipt by CannaSelection of a fully labeled and evaluable sample.

Conclusion: Establish data first, then decide

A stable grow does not result from making as many corrections as possible. It results from better decisions.

This does not always mean analyzing every level immediately. A step-by-step approach is often useful:

1. Check available water values using the CannaSelection water location search.
2. Evaluate your own values in the CalMag Calculator.
3. If the water source is unclear or treated, analyze an individual water sample.
4. If there are substrate problems, analyze a representative soil sample.
5. For self-mixed nutrient solutions, assess the finished mixture rather than only pH and EC.

The decisive step is separating assumptions from measured values.

A laboratory analysis does not provide a magical answer to every plant-related question. However, it provides something indispensable to a well-founded diagnosis: a verifiable data basis.

Based on this data, CannaSelection experts can work with your setup to derive specific, comprehensible and prioritized recommendations.

Water values already available?
Use the CannaSelection CalMag Calculator with the location search or your own analysis values.

Do you need values from your actual sample?
Discover the Living Soil Check, irrigation water analysis and nutrient solution check in the CannaSelection Shop.

FAQ: Soil, water and nutrient solution analyses

Are my water supplier’s values sufficient?

Often yes for an initial orientation. However, they must be current and match your actual supply area. Filters, water softeners, household plumbing, reverse osmosis systems, mixtures and storage tanks can change the water used. In these cases, analyzing the actual sample provides more meaningful results.

Are pH and EC sufficient for assessing irrigation water?

No. The pH value describes the current acid-base reaction. The EC value describes overall conductivity. Neither fully shows which individual minerals and salts are present.

Does soil analysis show the complete soil life?

No. The Living Soil Check is a chemical and physical substrate analysis. It does not include a complete microbiological analysis of soil life.

Can a laboratory analysis prove the cause of a deficiency symptom?

Not always. However, it can show whether the values examined fit the suspected cause. This makes it possible to confirm potential causes, make them less likely or investigate them more specifically.

Should I analyze Living Soil and irrigation water together?

For recurring problems, this can be very useful. The substrate shows the current condition of the root zone, while the irrigation water shows which substances enter the system again with every watering.

What is submitted for the nutrient solution check?

The fully prepared, ready-to-use nutrient solution—including regular source water, base products, additives and the usual pH adjustment. Concentrates or individual components are not suitable.

How long does the evaluation take?

Generally around two to three weeks from receipt by CannaSelection of a fully labeled and evaluable sample.