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Thread: testing water

  1. #1
    mikecrystalriver Guest

    Default testing water

    what is the best way to test my water for ph and how ofter should I change the water ( I have two tubs with tomatoe plants in them also the peters plant food is expensive can I use Micrle grow for tomatoes?

  2. #2
    Join Date
    Aug 2009


    The easiest way is with a digital pH meter or pen. However, they can be pricey depending on which meter you get - ranging from $20-$200. The 'what you pay for is what you get' rule applies here. I find pH meters in the $40 range as a good entry point. However you may want to consider a meter that also reads TDS (ec/ppm) for measuring nutrient strength.

    Another option are pH drops. You take a sample of your water, add the pH indicator drops and wait for the water to change color. You then match the color of the water to a chart and will give you an idea of your pH. Not as reliable as a pH meter, especially if your nutrients discolor the water.

    The cheapest option are pH test strips. Don't even bother with these.

    What type of growing medium are you using and how are you watering your plants?

  3. #3
    Join Date
    Jan 2012


    Depends on the growth of your tomato...

  4. #4


    You need to get a quality meter. I have on that was $75 and it measures PH pretty accurately and also tells me the temperature of the water. You will then need a TDS meter, which will tell you (in terms of parts per million) how many "particles" are in your water sort of. This allows you to know how much nutrients are in your water. If you are using anything other than reverse osmosis water (0ppm), than you are probably using tap water which may be around 200-500ppm depending on where you live.

    You can use the PH tester kit which is kind of like your pool chemical kit, you fill up a small vial with water and then add a few drops of the indicator fluid in there and it will change one of a variety of colors to tell you a general range of where the PH is. I DO NOT recommend this because it will say either 6, or 7 for example, but what if you need to keep it at 6.5? Then you are screwed. Really, spend the money on an actual digital meter, and don't buy a cheap one. The TDS meter will be around $40, expect to pay about $75 for the PH meter. Those are just the facts of life, they are what you need and that's that.

    As for the water, most would say to empty your reservoir and re-fill it once a week. This will help you keep the nutrient levels manageable too, because plants at various stages will drink a lot of water, leaving the remaining water in the reservoir over-saturated in nutrients. You can adjust for this by adding more PH balanced water if you don't feel like emptying it out. For me (and most people), you want to empty it out ever week, maybe 2 weeks at most. This will also help prevent nasty things from growing in there, or having sediment clog up your pump or whatever system you are using.

    As far as nutrients, do not use miracle grow. Buy quality nutrients (preferably a 3 part nutrient that has a bloom mix for the final bloom period), them and how much light your plants get are going to dictate how much growth you see. Don't feed your plants shit because the GIGO rule is at play here.

  5. #5
    Join Date
    Sep 2012


    Thanks “Outdoor_Hydro” for reply, it’s an informative reply for me and I will apply in my future cultivation.

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