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How to use a pH and TDS Meter in hydroponics

By Dr. Who

One of the most misunderstood tools for hydroponic gardening are the pH and TDS meters. The meters come in a multitude of varieties and styles, rang

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By Dr. Who

One of the most misunderstood tools for hydroponic gardening are the pH and TDS meters. The meters come in a multitude of varieties and styles, ranging in price from about $30 for a cheap “pen” to more than $250 for a combo meter which can measure in many different scales.

pH is short for “Potential Hydrogen.” This is a scale from 0-14 that measures the acidity or alkalinity of your nutrient solution. Most hydroponic nutrients perform best at 5.5-6.0 pH. If the pH is too low (acidic) or too high (alkaline), your plants won’t be able to take up nutrients, especially micronutrients. This leads to nutrient deficiencies, even though the correct micronutrients are in the solution.

TDS (Total Dissolved Solids) is also synonymous with PPM (Parts Per Million). This is a measurement of the quantity of nutrients in your solution. The number can be represented in many different ways. Sometimes it is represented in EC, or Electrical Conductivity. No matter what scale you are using, it is easy to get the results that you are looking for. Normally, plants require a nutrient strength of about 1,500-2,000 TDS (or PPM). If you have an EC meter, you are shooting for about 1.8 on that scale (1 EC equals approximately 900 PPM). The more expensive meters can read EC or PPM (TDS).

When you mix your nutrients, you should start with reverse osmosis (another article in itself), which has nothing in it. It reads 0 on a TDS or EC meter. The pH would be about 7.0 (neutral). You would then add your nutrients according to the manufacturer’s directions. This is a good starting point, and you should adjust the strength according to your own experience. If your TDS is too low, you should add more nutrient, mix the solution and test again until you hit the levels that you are looking for. Remember that you cannot force-feed a plant. Higher levels are not better. Too much nutrient leads to all sorts of oddities, with the results being that your plants do not grow as large or potent as they should be. Less is more.

After your levels are correct, you should use your pH meter to check the pH s. Many hydroponic nutrients are pH-buffered, which means that when adding them to the water, they automatically adjust the pH to acceptable levels, and they hold that level easier. If your pH level is at a low level, you should add pH Up (an alkaline liquid), and, conversely, pH Down if your levels are too high. Make sure that you use your pH Up and Down in very small amounts. In a 40-gallon reservoir, it might only take 10 to 30 milliliters to swing the levels .3 to .6 points either way.

You should monitor your reservoir and adjust the levels daily. Remember to change your nutrient solution about once a week, depending on the amount of nutrients that your plants are using.

The more stable that you keep your nutrient solution, the happier your plants will be, and happy plants make happy growers.

DR. WHO is a Southern California expert in plant cultivation. Reach him at drwho@freeculturemag.com.

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An Ice Cold Pitcher for Efficiency’s Sake

The water cooler of choice in the typical American home happens to be the refrigerator. It’s the keeper of food and drink, the place the kids hit first after a hot school day and the appliance that sees the most use. According to Michael Bluejay, “Mr. E

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The water cooler of choice in the typical American home happens to be the refrigerator. It’s the keeper of food and drink, the place the kids hit first after a hot school day and the appliance that sees the most use. According to Michael Bluejay, “Mr. Electricity” to the uninitiated, refrigerators is the second largest user of electricity, lagging only behind the air conditioner. For those families with kids who like to open and close refrigerator doors all day long, this amounts to a waste of 50 to 120 kilowatt-hours per year, or seven percent of the total energy use by this appliance alone. Refrigerator efficiency, it turns out, can be a big deal.

Many things can be done to improve the operating efficiency of refrigerators. Turning off the ant-sweat feature and setting the temperature to only as cold as is necessary provide some energy relief. Waiting until foods cool before storing them in the refrigerator is also good. Keeping a refrigerator full? That is where our potential energy savings can be found. Food acts as a buffer against warm air circulating in each time the door opens. Too much food or too little food in the refrigerator negatively affects the appliance’s operating efficiency, forcing it to work harder in order to maintain the status quo temperature.

Let’s say the refrigerator has plenty of space, but not so much food to spare. This is where storing pitchers or jugs of tap water can help. Pitchers of water operate in much the same way as ice packs do in coolers; it adds a much-needed buffer that insulates and keeps the interior cold, conserving energy. Not only does one have a ready source of refreshment awaiting thirsty kids at the end of the day, but one has prevented thousands more disposable water bottles from polluting the landfills. Another important fact: we avoid the waste that comes with waiting until running tap water transforms from tepid to cold.

So raise your glass and the jug . . . to energy efficiency and the thirst-quenching powers of Nature’s finest.

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Supplemental CO? can help optimize growth

By Dr. Who

Humans breathe in oxygen (O?) and breathe out carbon dioxide (CO?). Plants do the reverse. They “breathe in” CO? and

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Supplemental CO? can help optimize growth

By Dr. Who

Humans breathe in oxygen (O?) and breathe out carbon dioxide (CO?). Plants do the reverse. They “breathe in” CO? and “breathe out” oxygen (O?). This is why plant life is an essential part of the worlds’ ecosystem. Without plants, CO? levels would rise to intolerable levels. Plants use CO? for growth. It is the essential building block for photosynthesis (along with light and water). Plants cannot grow without CO?. The current levels in the atmosphere are about 350 parts per million (PPM). It is theorized that millions of years ago, levels of CO? were about 1,500 PPM. Throughout the years, plants have evolved in many ways—and in many ways have stayed the same. Knowing this can be advantageous for us all.

It seems that plants have not lost the ability to use up to 1,500 PPM of CO?. Plant growth can be accelerated by increasing the CO? levels in your growing area. Conversely, CO? levels below 250 PPM have a detrimental effect on your plants. If you have six plants growing in your closet, and there is no ventilation, your plants can use the CO? in a few hours. They then stop growing. You must, at a minimum, provide fresh air for your plants every hour or so. An even better way is to provide supplemental CO? for your plants by using either a CO? generator or bottled CO?. Any of these solutions will keep your plants growing at optimal rates. It has been proven that you can increase your growth rates by up to 20 percent and size by up to 30 percent by providing supplemental CO? at levels over 1,200 PPM. You should never go over 1,500 PPM, as this soon becomes toxic for the plants, and they tend to grow very stringy.

CO? generators are simply specialized burners that burn either propane or natural gas to produce CO?. A byproduct of this process is water, in the form of humidity. When using a generator, it is a good idea to keep an eye on your humidity levels. CO? generators are optimized to produce as little heat as possible, while producing as much CO? as possible. They are normally rated in cubic feet per hour (CFH). A standard 10-foot-by-10-foot-by-8-foot room containing 350 PPM takes about 1 CFH to raise the levels to 1,500 PPM. The level will drop throughout the day, requiring smaller burns to keep the levels constant. A CO? PPM controller works great for keeping your levels constant with a CO? generator.

Bottled CO? can be obtained at most hydroponic or welding stores. You need a regulator/flow meter to get the CO? out of the bottle in a measured manner. You set the flow rate in CFH and set the regulator on a timer to bring your CO? levels to the desired level. A few calculations will be needed to set your CO? levels correctly. You can also use a CO? PPM controller to maintain your levels.

Plants do not use CO? at night. It is not necessary to supplement CO? during your dark cycles (mushrooms are an exception). Properly used, supplemental CO? will only help your crops if you have all of your other factors in line, such as using a good nutrient mixed at an appropriate strength, changing your nutrients to prevent nutrient deficiencies, having enough (and not too much light) and keeping your temperature and humidity are also plant limiting factors. Once you have dialed in all these, supplemental CO? can help you gain the most return on your plant growth.

DR. WHO is a Southern California expert in plant cultivation. Reach him at drwho@freeculturemag.com.

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Growers’ Circle

How to Choose your Lighting
By Dr. Who

Lighting is one of the most important aspects of indoor growing. There are so many different kinds that it can be very confusing. The m

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How to Choose your Lighting

By Dr. Who

Lighting is one of the most important aspects of indoor growing. There are so many different kinds that it can be very confusing. The most common types are HID (High Intensity Discharge), fluorescent and compact fluorescent. Today, we’ll be discussing HID lighting.

HID lights are the most common type of indoor plant lighting. The two major types are high-pressure sodium, which gives off a reddish-orange light, and metal halide, which gives off a whitish-blue light. Both are available in many different wattages, with 1000w, 600w, 400w and 250w being the most popular. The wattage determines how large an area your light can cover, and also the amount of light penetration they will provide.

Metal halide (MH) lights are normally used for the initial vegetative growth of plants. Plants seem to respond to a whitish-blue light during the early stages. They tend to produce a more compact, shorter plant with tighter internodal lengths (the distance between the branches on the stem of the plant). This is very important to indoor growing, because if your plants “stretch” too much during the vegetative growth stage, they end up too tall and lanky during the flowering stage and do not produce the quantity of buds that a shorter, tighter plant will produce. One thing to keep in mind is that two-thirds or more of the ending height of your plants is done during the flowering stage, so keeping your plants short during vegetative growth is a must. You want to keep your plants under a MH light until you switch to the flowering stage (cutting the lights back to 12 hours on, 12 hours off).

A high-pressure sodium (HPS) light is the best HID light to use during the flowering stage. Plants have been shown to respond with larger yields under reddish-orange light, which mimics the fall sun. HPS lights put out more lumens per watt than MH lighting, and are therefore more efficient. Some growers believe that you can run an HPS light throughout the entire cycle with no ill effects on the plant. I prefer to use both types.

An HID light consists of three parts: the ballast (which is a transformer that changes the power from the wall outlet to a form that the bulb needs to light up), the bulb and the reflector. The ballast of a 1,000w light (the most common) can weigh up to 40 pounds, depending on the type of ballast that you choose. The older type, called Core and Coil ballasts have been used for many years. They are not very efficient, but they work very well and are extremely reliable. The newest type, the Digital Ballast, is the latest and greatest. They provide up to 30 percent more light with the same power usage as a Core and Coil ballast. In the past, Digital Ballasts have not proven to be extremely reliable, but the newest ballasts on the market are showing exceptional promise. A 1,000w Digital Ballast can weigh as little as 6 pounds. They can run either MH or HPS bulbs, so they are very garden-friendly. They should displace Core and Coil ballasts in the next few years.

There are many different kinds of bulbs on the market. I prefer to use the most inexpensive bulbs, as the “plant-specific” bulbs that are available do not give a noticeable increase in yield or light output. The most important thing to remember about HID bulbs is that after six months of use, the light output goes down dramatically—up to 25 percent. You should replace your bulbs every six months or so.

As with bulbs, there are many different kinds and types of reflectors on the market which prove reliable and put out an excellent spread of light. Do your homework to find your right fit, or just email me for advice.

DR. WHO is a Southern California expert in plant cultivation. Reach him at drwho@freeculturemag.com.

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