Hello all. I recently moved to a house with municipal water so I installed an RO filter. I plan on using this for watering/feeding. From my limited understanding, RO water has no minerals so it cannot be ph’d? Also should I be adding things like iron or any other necessary minerals? Is there a recipe for necessary mineral additives? Anything else I need to know about using RO water? Thanks.
2 Likes
Thanks. What about iron? Any other trace elements that the RO process removes?
2 Likes
A complete nutrient product such as Jacks 321 will satisfy the mineral needs a plant has. If using the Fox Farm Trio, then Big Bloom contains many of the minerals needed. A cal/mag product is required if using the Trio. Magnesium, and particularly calcium, are the micronutrients typically in tap water that are contained in a cal/mag product.
Good on you for picking up on pHing RO water. It is a common misconception that RO has a pH at all. Many references/websites state that RO has a pH of 7.0 to keep things simple. RO is indeed neutral, but in a different way than a solution with a real pH of 7.0 is neutral. A pH meter measures the charge balance of the ions in a solution. RO contains no ions and therefore has no pH. This comes up frequently and it drives me bonkers how often folks try to pH RO or distilled water.
9 Likes
Iron is contained in all complete nutrient products.
RO removes all trace products. Again, a complete nutrient product will satisfy a plant’s total nutrient needs.
I use Jacks with RO and grow plants like this. I’ve never had a nutrient problem when maintaining PPM at ~1,000.
9 Likes
Thank you. Much appreciated
3 Likes
She’s a beauty. 
2 Likes
Is it the same with rain water? Because when i measure it, its 0.0 EC
If the EC is truly zero, then yes it will be the same. An EC meter measures the density of ions in a solution. If the EC is zero, then no ions are present and no pH can exist.