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HOME + GROW INFORMATION + METERS & TESTING INFORMATION

INFORMATION: METERS & TESTING

Primer on nutrients and Ph
PH
chart-how ph affects plant nutrient uptake
Adjusting the PH level
Measuring the nutrient levels
Nutrient and Ph combo meters
nutrient and ph controllers
comparison of nutrients & ph meters
RESERVIOR AND WATER MANAGEMENT ORDER OF OPERATIONS
CHANGING THE RESERVIOR
CLEANING AND STERiLIZING EQUIPMENT
WATER TEMPERATURE
REVERSE OSMOSIS "PURIFIED" WATER
USING BENEFICIAL BIOLOGY TO PREVENTY ROOT ROT
ENZYME SOLUTIONS
THE OTHER ROUTE-KEEPING A RESERVOIR STERILE
IRRIGATION PUMP
FLOAT VALVE OR FLOAT SWITCH
MORE AERATION AT THE ROOT ZONE
DRAINING A RESERVOIR WITH THE HELP OF A "DRAIN PUMP"
KEEPING YOUR RESERVOiR TEMPERATURES COOL

 

Primer on nutrients and Ph
If you want your plants to excel, you need to pay close attention to the nutrient solution. By monitoring nutrients, not only can you feed your plants the appropriate level of nutrition, but you can also maximize the nutrients available for uptake. Monitoring the solution ensures plants will not be underfed nor burnt with too-high levels.

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ph
The pH value of a nutrient solution is a measure of the acidity or alkalinity of a solution. A basic, neutral solution is equal to 7 on the pH scale. The solution becomes more acidic as the numbers decrease and more alkaline as the numbers increase. The pH scale ranges from 0 (very acidic) to 14 (highly alkaline). Pure water has a pH of 7.

Different nutrients are absorbed at different pH levels. Most plants need a pH level between 5.8 and 6.5 for optimum nutrient uptake. If the pH is too low, nutrients are bound up and the roots are unable to absorb them. If the pH is too high, plants may succumb to toxic salt buildup, limiting the ability of the roots to intake water and food.

Your pH will fluctuate and should be monitored regularly. It can be tested with inexpensive pH papers, with a pH Shaker Tester, or you may choose to use a pH meter. pH meters come in various degrees of sophistication and price, such as the Hanna Checker 1, a cheap and effective entry-level handheld digital meter for pH. Some meters need to be turned on each time they are used. These cost less but need more frequent calibration to keep them reading accurately. We like the Hanna Waterproof pH, a durable, easy to use, accurate handheld meter. Other pH meters are continuous reading models which are always on and should be mounted next to the reservoir, such as the Grocheck pH meter. Further below we compare all the various meters.

You can tweak the pH of your solution to allow more nitrogen in the growth phases and then readjust during the bloom phase for more phosphorous uptake. Most importantly, adjust the pH based on what plants you're growing.

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Adjusting the pH Level
The pH level of your nutrient solution will need to be adjusted if it is too low or too high. You will want to keep bottles of pH Up and pH Down solution handy in your grow area. Use very little at a time and stir it into the nutrient solution thoroughly. The less you end up using, the better. If you use too much of one, you will have to correct it with the other. Be careful when handling these solutions as they can burn the skin. We sell three types of pH Up and Down solutions: Advanced Nutrients, the strongest stuff - made for larger reservoirs; Grow More pH solutions, which are cheaper and made for small to mid-size applications; and Earth Juice Natural pH Adjusters - All natural in a powder form.

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Measuring the Nutrient Levels
By monitoring nutrients, not only can you feed your plants the appropriate level of nutrition, but you can also maximize the nutrients available for uptake. Equally important, you can be certain that your plants aren't undernourished. Both EC & TDS meters give an easy-to-read reference point of the conductivity of nutrient in solution.

TDS stands for Total Dissolved Solids and is measured in parts per million (ppm). One ppm is one part by weight of the mineral in one million parts of solution. In hydroponics TDS is estimated using a conversion from the measure of electrical conductivity (EC). TDS is currently the standard of measurement that most US growers use. This will probably change in the future as manufacturers begin measuring their products in EC.

Like pH, TDS (and EC) meters come in two different forms. Handhelds, like the pH meters above, are easy to use, generally cheaper in price, and are great for checking multiple reservoirs with. We like the Hanna Primo TDS, an affordable entry-level ppm meter. The Hanna Waterproof TDS/EC Handheld Meter is also very nice. It is durable and easy to use, and is very accurate. Lastly, we like the “bullet-proof” Truncheon; it comes with a 5 year warranty, is easy to use, rarely ever breaks, and never needs to be calibrated. There are also continuous meters for reading TDS/EC only. However, most people interested in these want a “combo” meter...(keep reading).

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Nutrient and pH “Combo” Meters
Most serious gardeners will eventually grow into using a “combo” meter which will measure both pH and TDS. The nicer units will also measure Temperature, and lend a higher degree of accuracy by compensating for the effect temperature has on the readings. Along with temperature & compensation, some of the nicer meters will allow a change in the Conversion Factor ( what the meter uses to convert readings from Electrical Conductivity to the TDS (ppm) value ). There are handhelds and there are continious Combo Meters available.

The two handheld combo meters we recommend are the Hanna “Black” Combo Waterproof TDS/EC/pH Meter, and the more Industrial Hanna Combo (TDS/EC/pH) Meter with the remote probe. The Hanna “Black” Waterproof is nice because it is both temperature compensated and allows switching between EC and TDS scales. It also is very accurate and fairly durable. The more rugged Industrial Hanna “Combo” Meter sporting the remote probe is also temperature-compensated and allows more flexibility due to its remote probe feature, which can be placed in the solution that is being measured the whole time that the solution is being mixed. In this way, one can add nutrients and adjust the pH while occasionally swirling the probe without having to constantly turn the meter on and off to get new readings (like the other handhelds on the market).

The three continuous “combo” meters that we offer are the Hanna “Grocheck” Combo (pH/TDS) Meter, the Hanna TriMeter (pH/TDS/Temp), and the NutraDip TriMeter (pH/TDS/Temp). The Hanna “Grocheck” is great for entry-level combo users or growers who have multiple reservoirs and are on a budget. It is priced to be affordable, and can read pH, and TDS values accurately, but has no temperature compensation. The Hanna “Grocheck” continuously displays its values and makes for easy reference and mixing of your reservoir. The Hanna TriMeter adds temperature compensation and further accuracy and durability to the “Grocheck” meter design. It has a 1 year warranty on its probe, as well as 2 years on its body. Our final offering is the time-tested NutraDip TriMeter which measures pH, TDS, and temperature. (If you are a fan of the internet and its various ‘chat’ boards you will have heard its praise by now.) The NutraDip TriMeter is very durable and accurate. There are folks who have have used these bad boys for more than 10 years without any problems (it only comes with a 2 year warranty on the body and 6 month on the probe, though). Please note: We have not had many of these meters returned for warranty repairs, but it can take up to a month to get back from being worked on and fixed.

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Nutrient and pH Controllers
Nutrient and pH controllers allows the grower to monitor and precisely control the nutrient solution, achieved through the use of set points and duration dosage times. You simply program in the set points you want, and the controller will dose the reservoir with a set amount of nutrient or pH adjuster to bring the reservoir readings to the right level.

There are two delivery systems available for these controllers. One is gravity fed, using solenoid valves. The second method is with a pump delivery system which eliminates the restriction on where it’s placed (in gravity fed systems, the nutrients must be placed directly above the reservoir.) Both of these methods work well and once you have become acquainted with the parts involved, you will find them very easy to use.

There are several nutrient and pH controllers that we supply, varying in price and quality. The AutoGrow uses high-quality solenoid valves and comes with everything needed for set up right out of the box. It can be custom fitted for stand-alone pH or TDS dosing, or it can handle both. The more professional grower will be more interested in the IntelliDose. This unit can dose both pH and TDS/EC. It reads temperature levels (and is temperature compensated), and also has a built-in digital cycle timer which can be hooked up to a drain pump or main irrigation pump. The IntelliDose can also be connected to a computer for remote management and data-logging.

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Comparison of Nutrient & ph Meters

NAME/
DESCRIPTION

RANGE RESOLUTION/
ACCURACY
TEMP NOTEWORTHY REMARKS
HYDROPONIC METER
CHECKER 1
HANDHELD TDS BUDGET
0.00 TO 14.00
.01PH
±.02PH
N
Warranty: 1yr on body, 6mos on ph probe
Other Info: cheap, affordable,accurate, good 1st ph meter
Note:does the job, will break eventually. You will upgrade.
HYDROPONIC METER
PRIMO TDS HANDHELD TDS BUDGET
0 TO 1999PPM
(TDS FACTOR: 0.5)
1PPM
±2%F.S.
N
Warranty: 1yr on body, 6mos on ph probe
Other Info: cheap, affordable,accurate, good 1st ph meter
Note:does the job, will break eventually. You will upgrade.
HYDROPONIC METER
WATERPROOF HANDHELD PH PROFESSIONAL
-2.0 TO 16.0
.1PH
±.1PH
Y
Warranty: 1yr on body, 6mos on ph probe
Other Info: very accurate, easy to use, great solo ph meter
Note:Temperature compensation, need to store probe properly
HYDROPONIC METER
WATERPROOFTDS/EC PEN PROFESSIONAL
0 TO 2000 PPM
(TDS FACTOR: 0.5-0.7)
1 PPM
2%F.S.
Y
Warranty: 1yr on body, 6mos on ph probe
Other Info: very accurate, easy to use, can change to TDS conversion factor
Note:Temperature compensation, long lasting meter.
HYDROPONIC METER
WATERPROOFTDS/EC PEN PROFESSIONAL
0 TO 2000 PPM
(TDS FACTOR: 0.5-0.7)
1 PPM
2%f.s.
Y
Warranty: 1yr on body, 6mos on ph probe
Other Info: very accurate, easy to use, can change to TDS conversion factor
Note:Temperature compensation, long lasting meter.
HYDROPONIC METER
GROCHECK
TDS/PH COMBO CONTINUOUS
PH:0.0 to 14.0
TDS: 0 to 1990 ppm
(tds factor:0.7)
PH:0.1/0.2
TDS: 10 ppm/2%F.S.

N
Warranty: 2yr on body, 6mos on ph probe
Other Info: good overall entry level TDS/PH meter. Solid
Note:No temp compensation on this meter. not as accurate.
HYDROPONIC METER
HANNA 3-METER TDS/PH/TEMP CONTINUOUS
PH: 0.0 to 14.0
TDS: 0 to 1990 ppm
(tds factor:0.7)
PH:0.1/0.2
TDS: 10 ppm/2%F.S.

Y
Warranty: 2yr on body, 1yr on ph probe
Other Info: good overall meter. Long lasting, easy to read.
Note:doesn't often break, temperature is in Fahrenheit.
HYDROPONIC METER
INDUSTRIAL TDS/PH/TEMP HANDHELD
PH: 0.0 to 14.0
TDS: 0 to 1990 PPM
(tds factor:0.7)
EC: 0 to 4.0 mS

PH:0.1/0.2
TDS: 1 ppm/2%F.S.
EC: .01 mS/2%f.s.

Y
Warranty: 2yr on body, 6mos on ph probe
Other Info:industrial, well made, remote probe is very useful
Note:probe needs to be cleaned and calibrated often
HYDROPONIC METER
NUTRADIP TDS/PH/TEMP TRIMETER
PH: 0.0 to 14.0
TDS: 0 to 9990 PPM
(tds factor:0.7)
PH:0.1/0.2
TDS: 1 ppm/2%F.S.
Y
Warranty: 1yr on body, 6mos on ph probe
Other Info: known as the most solid continuous meters on the market
Note:doesn't break often, if it does it takes a long time to fix
HYDROPONIC METER
TRUNCHEON TDS/EC/CF BULLETPROOF
TDS: 0 to 2520 PPM
(tds factor:0.5-0.7)
EC: 0 to 3.6 mS
TDS: 50 to 70 ppm/2%F.S.
EC: .1 mS/4%
Y
Warranty: 5yr on entire unit
Other Info: bulletproof. this meter lasts forever
Note:doesn't need calibration just cleaning
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RESERVOIR AND WATER MANAGEMENT
If you want your plants to excel, you will want to pay close attention to what is going on in your reservoir. By monitoring nutrients, not only can you feed your plants the appropriate level of nutrients, but you can also maximize the nutrients available for uptake. Monitoring insures against underfeeding or burning.

Order of Operations
It is very important that you follow these steps (in this order) when adding anything to your reservoir solution (nutrients, additives, etc.) Please note: whenever you add anything to a reservoir solution make sure that you adjust the pH last. Even if you just add water to a reservoir solution you still need to adjust the pH. There are certain exceptions to this order and it will be indicated on a given product label or set of instructions.

  1. Start Out with Purified (Reverse Osmosis) Water. We recommend a UV filter be employed on any incoming water into your reservoir. This insures that the starting water is pathogen free.
  2. Add MagiCal up to 150ppms. In the last 3 weeks of the Bloom stage you can add 50ppms of MagiCal.
  3. Add additives, one at a time, stirring well in between This includes anything that is not your main nutrient.
  4. Test ppms and see where you are at? You should only be at 37% (or just over 1/3) of overall desired ppms. (Ex. If desired ppms for given week are to be at 1500ppms then you will not want to have more than 550ppms with your additives added to your water solution (at this step)).
  5. Add base nutrient (Examples of main nutrient: PureBlend Pro, Flora Nova, SensiBloom or Grow, Connoisseur, Any 3-Part Nutrient, etc.) as per directions (example: SensiBloom you add in equal parts A and B - If you add 100mL of A you will have to add 100 mL of B). Continue adding Nutrient until desired TDS is reached. (Ex. As in the previous example from step 3. the ppms after adding the additves were at 550. The desired ppms for that week are1500ppm. We now add 950 ppms of nutrient to the solution. CALL WITH QUESTIONS!
  6. Adjust the pH of the reservoir solution.
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Changing the Reservoir
A good rule of thumb is to always top off your reservoir with fresh water, without any nutrients added. You will lose some water through evaporation and plant uptake, but the strength of the solution doesn't drop the with the level of the solution. Sometimes, as the reservoir water level drops the nutrient solution can become more concentrated. To avoid overdoing it, add only fresh water and then adjust your pH accordingly. The best way to know when it’s time to change your nutrient solution is to keep a record of how much water you're putting in the reservoir to top it off. When the amount added equals half of the reservoir capacity, it's time to change the solution and rinse the reservoir and growing medium. If you've got a 20 gallon res and over the course of 12 days you've added 10 gallons, it's time to change your solution.

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Cleaning and Sterilizing Equipment
Sterilizing your equipment is extremely important and it is often handled incorrectly. Many people make the mistake of using Hydrogen Peroxide for sterilization. This happens to be a poor oxidizer, unable to kill many different types of pathogens, and is only truly effective at a pH of 2.0. A better choice is Bio-Green Clean, an excellent organic enzyme cleaner. It is especially good at scrubbing out those hard-to-clean white trays.

Bleach, although not the most environmentally-friendly product, is an old favorite. It can kill anything, and is very cheap, making it hard to resist. Do NOT use it sparingly - make a very concentrated solution. Soak your gear for at least an hour, and let it run through all equipment (including pumps.) Scrub surfaces with a strong bleach solution. Then make sure to do multiple rinses with plain water to rid the trays of any residuals. When using strong bleach solutions, wear gloves and work in a ventilated area.

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Water Temperature
Although expensive, nothing works better for controlling water temperatures than a water chiller. It is of critical importance for a healthy root zone that water temps stay between 66-68 deg. F. This does not mean that temperatures can sometimes be above or below this temperature, only that the solution should consistently remain in the 66-68 deg. F. range. At this temperature, the nutrient solution holds a good amount of oxygen, and the nutrient absorption rates are still high enough for most plants. See the “Best Overall System Setup” info sheet for more info.

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Reverse Osmosis “Purified” Water
Why would you drink purified water and not feed it to your prized plants as well? Reverse Osmosis (RO) water is purified of all contaminants, minerals, and chlorine, effectively cleaning the life-blood of your plants’ vascular systems. Coupling an RO water purification system like the Merlin Garden Pro or the Stealth 200 with a UV filter system ensures that your water is fresh and clean and also free of any pathogens. See “Best Overall System Setup” and “Why should you consider Reverse Osmosis” info sheets for more info on this topic.

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Using Beneficial Biology to prevent Root Rot
There is a complex relationship between plants and the microbes that live in and make up the rhizosphere. As growers we we want to innoculate and promote healthy microbe colonies. Some of the more common varieties to look for are Mycorrhizae, Trichoderma, and Bascillus Subtillus. There are a plethora of products that help us in our endeavors, including Roots Excelurator (the Best Protection Product we have)Vermi-T, Piranha, Subculture, Tarantula, Voodoo Juice, and HydroGuard, to name a few. We even brew our own concoctions.

See “Beneficial Biology”, “Best Overall System”, and “Root Zone info sheets as well.

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Enzyme Solutions
Small, yet amazingly powerful, enzymes have a variety of important benefits for the grower. There are many different enzymes and all have different functions. We are most concerned with two types of enzymes: those that accelerate sugar / resin production to create flavor and aroma, and those that break down dying and dead plant proteins (dead leaves and roots) into their component parts – amino acids, lipids and smaller molecules which can be reabsorbed by the plant and the beneficial microbes. This also prevents those proteins from becoming food for pathogens. Some of the enzyme solutions we like are Hygrozyme (for better, faster overall growth), Sensizyme, Cannazyme and MultiEnzyme for enzymatic breakdown of dying root tissue.

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The other route - Keeping a Reservoir Sterile
Some growers rely on “clean” growing environments, strong disinfectants, and products to sterilize the reservoir. This is harder than it sounds. Folks who have been growing in the same area for years might find that they are having root problems when they never had them before. Or a new grower might have them from the beginning. In any case, it can be tough to rid your area of pathogens once they have been introduced.

Zone: Comprised of monochloramine and essential oils know to ward off root disease. This is the strongest sterilizing agent that we sell. It is easy to use and works well at preventing root disease. Can be used at 2-3x strength to fight an infection. (Make sure to NOT add any beneficial microbes or enzyme solutions to the mix.)

Hydrogen Peroxide: Creates ozone in water, killing bacteria & adding oxygen to the system. Elevated levels of oxygen in water have proven to dramatically increase the speed of plant growth. Recommended (in HIGH concentrations) for cleaning as well.

UV - Filter: Use of a UV filter can greatly help win the battle against pathogens. As long as the nutrient solution is clear when it runs across the filter, (i.e. no organics,) any microorganism’s DNA will be torn apart.

PLEASE NOTE!! Both Zone and Hydrogen Peroxide offer protection and benefits. But NEITHER works well with beneficial biology or enzymes added to the reservoir. Hydrogen Peroxide doesn’t work well with anything organic.

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Irrigation Pump
An irrigation pump is used to pump water from the main reservoir to the Hydroponic / Soil Delivery / Drip system. Since there are so many brands and sizes of pumps to choose from, it can be quite hard to figure out the proper size pump for your given system. It is best to talk to us about it first. (Also note: All pumps are not created equal. Even though two pumps have the same GPH rating doesn’t mean they will output at the same rate.) Make sure to ask a sales person about the differences.

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Float valve or Float Switch
Float valves are a simple concept that can help insure a hydroponic system always has enough water. You'll notice the float valve is attached to the right side of the reservoir, with a water line coming in. At first glance a float valve might seem difficult to use and operate, but in truth the concept is easy and accessible. Float valves work in a similar way to a toilet. When the water level of the reservoir drops, it causes the float valve to drop with it, thereby opening up the pathway for water to flow into the reservoir. When the reservoir is filled up again, the float valve rises back up with the water and closes off the pathway, thus restricting water from passing through. Float valves can be used to connect one reservoir to another, or they can be connected directly to a water filtration system directly such as The Merlin Garden Pro or the Stealth 200. In between the float valve and the incoming water line we like to put a ball valve (giving you more control of when the water is flowing into your reservoir.) We can help - Talk to us about installing a float valve. It is actually cheap and easy! This provides for automated water filling. We also believe in employing a slightly more sophisticated float - called a float switch; involving a watering timer. Inquire within!

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Aeration within the water leads to More Aeration at the Root Zone
Most reservoirs need some form of aeration. Oxygen is very important for healthy roots and aerated water provides bonus oxygen. We suggest using either an air pump, air stone or venturi, or a combination of all three. None of these is depicted in the picture above. The other types of systems will need extra oxygen, depending on the type of growing media used. We suggest the biggest air pumps you can find! Your reservoir should be bubbling like a hot tub!

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Draining the reservoir with the help of a “Drain Pump”
Since draining the reservoir is a regular event (about once a week), we suggest using a separate drain pump to speed up the operation. This pump should ideally suck from the bottom in order to assure complete and thorough drainage. Examples of good drain pumps are the Little Giant PE-1 for smaller reservoirs, the NK-1 or NK-2 for medium size reservoirs, and a Water Wizard hooked up to 3/4” hose line for larger reservoirs.

Nutrient and pH Control
Although not depicted in the diagram above, a good reservoir setup will always include a continuous pH / TDS / water temp monitor such as the GroCheck TriMeter from Hanna or the NutraDip Trimeter. This meter will continuously display the pH and ppms of the nutrient solution, allowing for greater control. Water temperature is also very important to monitor. We suggest the use of a water chiller. (see below). For more automated control, check out the IntelliDose from American Hydroponics. It will monitor and control pH and ppm values at ALL times.

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Keeping your Reservoir Temperatures Cool using a Water Chiller
A water chiller is one of the most over-looked and most needed component to a healthy reservoir. A water chiller assembly employs a submersible pump to move water through the chiller and back into the reservoir solution. Chillers can be set up to have a differential so that they are not always running. Ideal water temperature is between 66-69 deg. F. The chiller will bring the water down to 66 deg. F. and then turn off until the water is up to 68 deg. F. (We like EcoPlus Chillers or Frost Boxes over any other because they are well made, more durable and longer-lasting. Of the two, the Frost boxes are a large step above.)

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