pH Testing in Hydroponics Explained

pH Testing invokes this image of a mad horticulturalist muttering an arcane ritual over a set of vials when nothing could be further from the truth. pH testing is simple and easy to understand.

First off – what is pH? It stands for the rather cumbersome potentiometric hydrogen ion concentration. Simply put, it is a measure of the acidity or alkalinity of a solution. The pH scale is from 0-14 and pure water has a neutral pH of 7. Anything that would be considered acidic is rated lower than 7 and anything considered alkaline is rated higher than 7. Pretty simple.

How does this affect my hydroponic system and why test for pH? Well, different plants require different pH to get optimal growth. Testing your growing solution allows you to correct any imbalances in allowing you to grow bigger and better plants. It is one of the simplest and least technical ways to increase your produce yields and plant size. Think of it as part of providing the best home for the roots of your plants – allowing them to feed at the best rate possible. Always add the nutrients to the water before checking and adjusting the pH of your solution. Should your pH level go too high or too low the nutrients in your system will settle out – leading to deficiency and death.

The simplest and least expensive way to test water pH is paper test strips. The strips, which have a pH sensitive dye on them, change colour when dipped into your nutrient solution. You compare the colour on the strip to a colour chart to determine the Ph level. Nothing complicated about that. The only down side is that the strips can be hard to read because the colour differences can be subtle.

The most popular method to check pH is liquid test kits. The liquid test kits work by adding a few drops of pH sensitive dye to a small amount of the nutrient solution your hydroponic system uses and comparing the colour with a colour chart. These kits are a bit more expensive than the paper strip tests but are much easier to read and are extremely accurate and reliable.

For the technologically gifted, the most high-tech way to check pH is to use the digital meters. They come in a huge array of sizes and prices. The digital pen style meter is the most popular. Just simply dip the electrode into the nutrient solution for a few moments and the pH value is displayed on an LCD screen. They are very handy and easy to use. Digital meters usually need to be calibrated frequently, as the meters can drift and you must check the calibration often to insure accuracy. Most pens also require the tips to be stored in a buffer or electrode storage solution and have a reputation of breaking down without warning.

The major requirement of pH testing asks you to be able to compare colours – making the pH of nutrient solution component of your hydroponic system easy for you to understand and maintain. No mad horticulturalist and certainly no arcane rituals needed.

The Importance of Ventilation in Hydroponics

Fresh air is at the centre of successful indoor gardening. Outside, air is abundant and almost always fresh. C02 levels in the air over a field of rapidly growing vegetation will vary on how still the air is. Being outdoors, and subject to the warming and cooling of the day, the wind blows in fresh air. Rain will cleanse the air of dust and pollutants.

The outdoor environment is always moving. Plants grown indoors do not have the natural balance that is present out of doors and must be achieved indoors by way of fresh air ventilation or CO2 enrichment.

So you have decided to add CO2 to your hydroponic systems. Great! Welcome to the wonderful world of bigger yields. Now having said that, there is a caveat – like all good things – there can be some events to watch out for. For our purposes we will be dealing with the increases of humidity in a CO2 enriched environment.

Now what is humidity? Simply put – humidity is the water vapor present in the air.

There are various devices used to measure and regulate humidity called psychrometers or hygrometers. You can regulate the humidity of a room with humidistat a variety of tools in your growing arsenal. These are comparable a thermometer and thermostat for temperature control. You can find from most retail outlets combination hygrometer/thermometer unit – we recommend looking for a quality wireless unit for ease of placement.

The humidity level should be in the range of 40-75% when your lights are on which can be measured with a hygrometer. Now the warmer the air, the more retained water- this means humidity levels can easily go beyond the recommended 40-75%. High humidity like this coupled with lower nighttime temperatures (a requirement to get plants like orchids to bloom) can cause condensation to form on leaves. Which means your hydroponic system would be a prime candidate for all sorts of fungus issues, like powdery mildew. Inadequate ventilation is the primary cause of most fungal diseases.

How do you prevent this?

Ventilation fans – both intake and outtake- help regulate temperature, CO2 levels and relative humidity. During the winter months, you're more likely to need a ventilation fan for dehumidification rather than reducing temperature. Air is not exchanged as frequently in winter, so plants naturally raise humidity without air being exhausted. Fans at too high a setting combined with high heat can lead to lower humidity levels as well – find the balance for your hydroponic system and it will take care of itself.

Blowers

These remove heat, which accumulates rapidly in indoor growing situations. Excess heat can result in excess humidity as the air retains for water. By pulling air in the side of the blower and pumping it out the front. For mounting on a wall or inside a grow box units have a flange on the front. Some feature a round inlet flange for connecting ducting so you can pull air from another room.

Keep fresh air flowing, and watch your indoor garden grow!