RO water and pH concern

Discussion in 'Forum Tech Questions, Problems and Troubleshooting' started by afghoon, Mar 3, 2013.

  1. Briefly,
    I installed a RO water filter to supply my plants watering needs. Followed instructions and took a water sample. I use a Blue Labs pH/temp/ppm meter. I have very hard/sulphury water in my well. Once through the RO unit the TTD's were 60....20....10ppm.( and dropping with each gallon drawn) No sulphur smell. The temp was 57F. The pH was 7.8. I added pH down from GH to make a gallon of RO water with a pH of 6.0. Here comes the silly question: The water is now "lightly colored" due to the orange pH down I used. I took a sip and WOW it was very "acidic." My question is should I be concerned of the taste? Will my plants actually like this level of pH? I know the meter says it's OK but I just don't want to injure some gorgeous sprouts with water that tastes like battery acid. I would appreciate any advice.
  2. If your meter is right then everything will be fine. ph of 7 for soil and 5.2 for hydro. Because your using ro water though you need a cal/mag supplement.
  3. I have had the meter for over a year. I just ordered some calibration solutions and I'll re-calibrate as well as check the TDS probe. If I remember correctly I used less pH down when the probe/unit was newer. (Pre RO unit) I sure do appreciate the response! I have had loads of luck with soilless planting and just know the quality/yield can improve with hydro. DWC set up. I WILL be back!!
  4. I'd try to get in the habit of recalibrating your meters before every new grow or every 3 months. Good luck.
  5. never measure the PH of RO water because it's not accurate due to the lack of buffering agents.

    just use it straight or add whatever you like to it and (((((then)))) adjust PH if needed.
  6. Thanks for the info. I recalibrated my probe and it was off enough to have been a water quality problem in the past. Also, in the past I would put cuttings in a homemade cloning box. I never use root-growth dips or nutes, just water. The water out of my RO unit now is exactly 7.0. I had always kept the water in my reservoir at 5.9. IF I'm not adding anything but water to the cloner should I THEN adjust the pH or just leave it alone. I was going to get it to 5.9 but I'll wait for some unbiased opinion.
    Again, thanks so much!
  7. In my experience you want all hydro setups at between 5.2-5.8 in ph.
  8. Awesome. Can I assume that between those parameters(5.2 - 5.8) the majority of elements are available? Would that alone be the reason for such a pH level??
  9. In hydroponics, yes that is the best ph range.
  10. Thanks IA!

  11. yeah RO water has no buffering so the PH will rise and drop on an hourly basis if you measure it enough. reason being there are no ions to measure, so whatever reading you are getting, is false anyway.
    stick to 5.8 to 5.9 on the hydro and you should be golden.
  12. #12 afghoon, Mar 10, 2013
    Last edited by a moderator: Mar 10, 2013
    The lack of ions makes sense. Sometimes things are too simple and I have to make it complicated. Let me just get it straight...Setting up the veg/flower reservoir I add the suggested amount of nutrients per gallons of RO water and THEN I adjust pH to the 5.8 - 5.9 range?

    Also, if I use just RO water to start cuttings/clones do I leave the cloner water pH at the level it is out of the RO unit? I would "guess" that since the plant/mother was used to the 7.0 pH then it's cuttings or clones would like the approximate same pH level? ( The water out of the RO unit is "approximately" 7.0 +/- )
    I hate bugging people but once I get it right I feel I should be able pass on accurate information and be able to explain it enough that an expert would agree with what I practice. (Expert= anyone but me) Thanks again!!

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