Is RO water better for soil grows?

RO water in all cases is better. But, depending on your tap water conditions you may just be able to use that. Remember there is chlorine and fluoride in your tap unless you have well water. So all those chemicals hurt things and minerals could build up if ppm of water is high. I buy 20 gallons of poland spring a week and that works well.

yea, use RO, if your tap water is "bad" other wise use the Tap water, that or make a rain collector if possible, plant love it and PH is perfect, with Tap you will have some micro/trace elements in it like Calcium (I have a lot and a high PH Bc. of it) so need to adjust your nutrients according to it, but not a big deal in a good soil, another thing is if your water plant (look up there home pages most have it all posted there) add chlorin, then you need to let it stand out for a day or two in the Can to make it evaporates, let it stand out a day anyway to make it room temperated, roots don't like ice cold water


on a side note, if your in good organic soil with lot of micro life, the soil will take care of the PH in most cases if its not totally off and that would possible mean your Tap water is`t the best choice ..

I've been looking into this and so far can't find a significant difference between rain water and RO water. Assuming you are not getting rain with dissolved pollutants, both RO and rain are nearly pure water, with a few ions, etc.

If anyone has any hard data on this, I'd be very interested.

The question is "is RO water better than what"?

Rain water? Well water? Tap water? Tap water and well water can have a pretty broad range of things in there or pH depending on the source.

Specifically, tap water "can" have chlorine, chloramines, fluoride and other things in there that in high concentrations may not be so good for your plants, but with the exception of chlorine (which will dissipate on standing), most of these things "should" be in pretty low levels and not particularly harmful. Remember, people water their lawns, gardens, drink and bathe in this water every day. In many cases commercial crops are grown using the equivalent of public water (or in many cases LOWER quality water).

Bluntly, if your tap water is of decent quality, you let it sit a day before watering your plants with it, and you're using a decent quality soil I doubt you're ever going to notice a difference of tap water vs distilled or R/O water.

On Ph-ing water, some people make a big deal of this, but again, I think its a lot more relevant to hydro where the medium IS water and the plant has to get all its nutrients from there. In that case, the plant is sitting in a chemical solution (which may or may not be buffered or pH-balanced to begin with), and its own metabolism is eventually going to change the pH of the medium.

In most places, ordinary water from the tap is going to be in a plant-acceptable pH range. More important, soil itself acts as a buffer to normalize pH, and you're constantly adding new water.

I like distilled water to insure there isn't any buildup of minerals over time. Sparklets makes a decent distilled water that is supposed to be at the 6.0 range, so if you add nutrients to the water it will most likely bring that ph up higher, especially if there is nitrogen, but then adding some epsom salt should combat that, no more than 1 tablespoon per gallon. While I don't ph my mix, I haven't had any deficiencies that I have noticed. I'm also using Miracle Grow soil and that's really why I'm adding the epsom salt to the water, cause miracle grow lacks magnesium that is necessary for N-P-K uptake. For nutrients I'm feeding it regular old miracle grow water soluble nutrients. I suppose you can spend more and get fancy soil and fancy nutrients, but I've found you just need miracle grow soil, the correct water, and miracle grow nutrients, and you can do it just as well. Now some tell me you'll want a higher ph for flushing, but I think with the MG soil it'll put the ph too high if you start with a higher ph water and then the plant won't be able to process all the excess nutrients properly and actually flush itself. All you really have to do is keep in mind that MG soil is a little on the acidic side and you'll should be fine. I suppose if you're scared you can go buy a ph meter and strips and go through all that to fine tune everything, but I never do.

A plant does not flush itself and you cannot "flush" it. You have marijuana confused with toilets.

Originally Posted by Canna Connoiseur

RO water in all cases is better

Totally incorrect and an opinion - not fact. In fact, most RO systems stay busy and waste membranes removing calcium and magnesium for most municipal water systems. Then those users are back on here "help!Is my baby burned or starving" and being advised to add cal/mag. RO is totally an unneeded expense and hassle for 99% of growers.

If a person had access to rainwater, would you suggest they use it? Likely not, as it would create the same issues in anything but a real soil grow.