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PPM problem

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Old 06-11-2016, 01:36 AM
Forma Forma is offline
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Join Date: May 2016
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Default PPM problem

so my maxibloom says 1 teaspoon per gallon and I have 3 gallons in my reservoir. I add 3 teaspoons, check my PPM and it's like 200? So I just kept dumping in tablespoons until I got around 1000. I'm not sure why it would recommended 3 teaspoons and took me 6 tablespoons. Could my TDS meter need calibration, it's recently new. This happened to my last week when I cleaned the tank also, but I was using the 3 part liquid series and dumped the whole 3/4 the bottle in there before I got the required ppm. Didn't kill my plants or any sign of nut burn. Another questions, when calculating ppm should I be using my tap water base ppm then add it to my after nute ppm to get a final ppm?


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Old 06-11-2016, 04:54 AM
GpsFrontier GpsFrontier is offline
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Join Date: Mar 2009
Location: Lake Havasu AZ.
Posts: 1,855

Hello Forma,
Some meters don't automatically adjust for temperature, so you want to check that issue. But regardless, PPM/TDS/EC and pH meters aren't worth the money. Not only do they often give false readings, they can give false readings even when calibrated, stored, and maintained properly. Even though hydroponic supply stores try to convince you otherwise, truth is you don't need electronic PPM/TDS/EC and pH meters. Just fallow the nutrient manufactures mixing instructions. MaxiBloom nutrients say to use 1-2 teaspoons per gallon of water. 1 teaspoon= 50% strength, and 2 teaspoons= 100% strength. As long as you know how much to use for full strength nutrient solution, you can dilute it as needed. As for pH, that's very important to know, but pH drops won't give false readings, are easy to read, and don't need to be adjusted for temperature or calibrated. The pH drops are much easier to use, much more reliable, and far cheaper.

Another questions, when calculating ppm should I be using my tap water base ppm then add it to my after nute ppm to get a final ppm?
Now you see this is exactly why I don't even own a PPM/TDS/EC meter, they simply cant do the only thing I want them to be able to do. That is tell me if my nutrient solution is balanced. In order to be able to do that it would have to be able to tell me exactly what elements are in the water, and the exact amount of each one. But they simply cant do that, they only tell you the total of everything combined, so your left still not knowing what is in the water. When you check the PPM/TDS/EC of the water source you get a number on the meter, but you don't have any idea what it is that is in the water.

You can assume your nutrients are balanced as soon as you mix them up, but since you don't know what is in the water supply, you have no idea if that is throwing off the balance of your nutrients, and/or by how much. That's the information you would need to know in order to decide if you should go by the before or after adding the nutrients numbers. Water quality is very important in hydroponics. Not that the specific number/value you get from the meter is that important, but to simply know how unbalanced your nutrient solution is because of what elements might be in the water. As an example: if your water supply is high in calcium, that will change the balance of calcium in your nutrient solution. If your plants consume lots of calcium, that could be beneficial, but if not the excess calcium could could be a problem.

Since PPM/TDS/EC meters cant tell you what is in the water, and/or how much of it there is. The best thing to do is start with a good quality water supply in the first place, and because the plants will consume the nutrients, but not evenly, change the nutrient solution when needed to keep it balanced.

As for before or after adding the nutrients? People will do it both ways, it's more a mater of experience than anything else, and again you don't need a meter to gain that experience. It's a mater of watching your plants grow and looking for signs of overfeeding and/or nutrient depletion in your plants.

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