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In my hydroponic system, I need to control the ph level with natural household items without harming the plants. Currently, the ph level is very low (3). Any one know how to do this both ways?

M Watt
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  • And why are you limited to "natural household items" - (and what does "natural" mean in that case?) This frankly sounds most like a homework question, which makes me less inclined to answer it without clarification. You only learn from your homework by actually doing it - yourself. – Ecnerwal Jan 29 '18 at 01:24
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    @Ecnerwal Natural means "No harmful chemicals" – M Watt Jan 29 '18 at 01:36
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    Better get rid of the water then, I hear people drown in the stuff. {sure they die from lack of it too, but it can be harmful - which is another way of saying that's a very, VERY vague and essentially useless definition or criterion} Or salt - a bit won't harm you, too much will, and not much at all harms most plants. – Ecnerwal Jan 29 '18 at 01:44
  • So, this is a recirculating system rather than going to waste? – Graham Chiu Jan 29 '18 at 02:24
  • @GrahamChiu Yes. This is a DWC system. – M Watt Jan 29 '18 at 03:03
  • Why is the ph so low? And what's the water you're using, and pH? – Graham Chiu Jan 29 '18 at 03:05
  • @GrahamChiu I used ph paper to measure the ph level. This is normal tap water. Also tested in well water. They both give a reading close to 3 without adding any nutrient solution. So there might be an issue with the water or the ph paper is inaccurate. I'm going to buy a proper ph meter today. – M Watt Jan 29 '18 at 03:16
  • Well that's highly unlikely your tap water is pH 3. You can get aquarium test kits to check the ph. – Graham Chiu Jan 29 '18 at 03:18
  • @MWatt Don't forget to get the pH 4 and 7 standards for calibration. The stick type meters, about $12.00 at Amazon, work nicely, but are affected by the magnetic fields of stir plates, motors etc. Turn those off before measuring. pH 3 water should taste sour, so something is wrong with your strips. I never trusted the things anyway. – Wayfaring Stranger Jan 29 '18 at 13:18
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    If your water *is* pH 3, and you have copper pipes, you might have a problem with copper leaching from the pipes, which would not be good for you or your plants. It also makes the pipes leak, eventually. Decent quality test strips are quite reliable; poorly maintained meters are not, so if you are going to get a meter, take care of it properly (they are kinda fussy.) – Ecnerwal Jan 29 '18 at 19:08
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    You can just buy some bottled water, preferably from New Zealand, and test your pH strips. – Graham Chiu Jan 29 '18 at 23:43
  • @GrahamChiu - I like the plug for NZ, but really, wouldnt it be better to steer him towards distilled water or (PH4/7) PH calibration solutions ? – davidgo Feb 14 '18 at 07:52
  • Distilled water is not readily available. Every supermarket has bottled water. Might as well buy the best if you can. Or use the condensate from your dehumidifier. – Graham Chiu Feb 14 '18 at 09:07
  • Those inexpensive pH meters, which look like yellow sticks, are sensitive to the magnetic fields produced by motors, particularly stir motors. When you use one, turn off the stirring, and wiggle the meter around, being careful not to dip it below the ridge the cap fits to. There's electronics up there that don't like getting wet. Get both pH 4 and 7 standards. You'll need them. I'd just use Phosphoric acid to lower pH, and Sodium Phosphate dibasic to raise it. Both are readily available online, cheap. Messing around with lemon juice and household ammonia is just going to get you in trouble. – Wayfaring Stranger Apr 23 '19 at 16:53

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Whether or not your household has any right now, probably the least likely to kill your plants common substance to raise pH would be ground limestone. In some systems limestone or marble chips are used, which last longer but act more slowly than the ground dust-like material.

Ecnerwal
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    I'd use Red Devil drain cleaner (sodium hydroxide), but that's probably not what M Watt means by a "natural household item". – Wayfaring Stranger Jan 29 '18 at 13:20
  • Most plants are intolerant of sodium, so neither sodium hydroxide nor sodium carbonate nor sodium bicarbonate are particularly good options for a plant system. – Ecnerwal Jan 29 '18 at 19:03
  • It should only take a few millimolar (0.04g/L) to get the pH up where it belongs. That's not enough to harm a plant. – Wayfaring Stranger Jan 29 '18 at 20:28
  • An easy excellent source of small size limestone gravel is a pet shop. Look for "crushed coral" = aragonite = limestone aquarium gravel. – blacksmith37 Jul 19 '21 at 14:21
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I very much doubt that your tap water and deep water culture have a pH of 3. Nutrient lockout occurs below 5.5 yet your plants mostly seem okay based on your previous question. City water tends not to be acidic as that would corrode pipes.

Furthermore as plants take up nutrients the pH tends to rise and as you add nutrients the pH falls. So one would expect your water to be alkaline.

In flood and drain systems the pH might be too high if you had grow media with too much calcium carbonate, or concrete tubs. So to raise the pH you could add dolmitic lime. Baking soda contains too much sodium which your plants won't like. Some people use sea shells, and egg shells to help buffer the pH.

Graham Chiu
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  • Oyster shell is commonly sold as a supplement for chickens, and will work similarly to limestone or marble chips. – Ecnerwal Jan 29 '18 at 19:11
  • @Graham Chiu You're exactly right! I bought a professional PH meter and tested. My solution have a PH reading of about 5.94. I think It's completely safe! Thanks for the help! – M Watt Feb 08 '18 at 10:17
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Egg shells work well. If they have any egg whites left on they will make the water foam which lowers the water leval, so rinse them well.

Rachel Robinson
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