Is RO water better for soil grows?

Is it really better to use RO water for soil grows or is it a waste of money. I understand why you would need RO for hydro. BUt for soil it seems over kill.

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.

Canna Connoiseur said:

RO water in all cases is better

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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.

Rain water is very good but totally lacking in any nutrient content. In that case it makes sense to be prepared to add nutrients. I was simply saying it seems a fool's errand to remove calcium and magnesium and then run to the store to buy cal/mag.

I run straight tap water in my soil and in my DWC units. I do adjust pH for both but with less concern about it in soil. Why people think pot is so vastly different than any other plant is beyond me.

Rrog said:

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.

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Yeah rain water and R/O water are the best .. Like Rrog says unless you live in a polluted area or near a power plant I wouldnt use it. Also dont let your rain water sit.. The minute it stops raining put a lid on that sucks you dont want any pests like mosquitoes or gnats dropping larvae in your collected rain water.

hotrodharley said:

Rain water is very good but totally lacking in any nutrient content. In that case it makes sense to be prepared to add nutrients. I was simply saying it seems a fool's errand to remove calcium and magnesium and then run to the store to buy cal/mag.

I run straight tap water in my soil and in my DWC units. I do adjust pH for both but with less concern about it in soil. Why people think pot is so vastly different than any other plant is beyond me.

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Im not disagreeing with the fact that you cant use Tap Water but in some cases you have to use R/O. It's all about location. I'm pretty sure you wouldnt use the tap water in AZ. Some people have well water and some people have salt water softeners in their house and R/O is a must. Now I been to other states where the tap water tastes like bottle water.. ( Colorado has some good fucking water )

Rrog said:

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.

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The difference between the 2 is this. For every gallon of R/O water that comes from the tap 2 gallons of water are rejected and wasted down the drain. Other than this they are about the same. Unless you live downwind of a major industrial area. In which case you have the possibility of acid rain. A simple check of the ppms can answer that. You can spend the money to get a recirculating R/O system which can be expensive though. Get your tap water tested at your local health department because more than likely your tap water will grow just fine. And even better in some cases over R/O and your not spending money on calmag........

And distilled water is a no no in container growing. It generally carries a negative charge and has been know to cause all sorts of funny issues in a grow. Save the distilled for flushing when/if you ever need to. Thats when its negative charge is a good thing.......

If growing in soil, no cal mag needed. This whole water issue is really only an issue for soil-less and hydro. Real soil + microbes buys you a lot of forgiveness. Having said this, Cl- is never a good thing.

Rrog said:

If growing in soil, no cal mag needed. This whole water issue is really only an issue for soil-less and hydro. Real soil + microbes buys you a lot of forgiveness. Having said this, Cl- is never a good thing.

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Thats what I'm saying .. I was a hydro guy for quite a few years and yes I bought Cal/Mag bottles because I used R/O.. Soil / Organics you arent buying Cal Mag. My soil is charged with all the cal / mag it needs.

It sure is!!! Gotta love soil.

tons of poison in tap water...i dont even water my outside garden with the tap....chlorine, chloramine, flouride, perchlorate (where i live at least - its a rocket fuel constituent) etc.

also my rain water here is contaminated, so I use RO. used to supplement with cal/mg - now I believe my soil is complete to the point where I won't need to supplement except for maybe a light topdressing of oyster shell or sul-po-mag etc. down the road.

rrog - I would think that good, pure rainwater (which you should have in your neck of the woods) would be superior to RO simply because it probably contains some local microbes which were in the air. i'm sure there is more to it like EC, etc. that might factor in, but i really have no scientific basis for any of this...ask coot, i'm sure he has a link somewhere...

I agree Cann. I water with Blumats, which require a constant pressure water source. I used to use well water, with a pressure reducer. Works great, but Ca buildup over time isn't good. So looking to set up RO filtration, with a pump to increase the pressure, then a pressure reducer to feed the blumats just what they want.

hotrodharley said:

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.

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I agree 100%. RO is just wasteful in most situations. Especially if you're growing organically. As long as your water isn't ridiculously hard, your much better off with a simple chlorine/chloramine removing filter like a Small Boy or Tall Boy. Be sure to purchase the upgraded catalytic carbon for chloramine removal.

Rrog- You can dissolve off Ca buildup ("lime scale") with white vinegar. A tube flush once a month with white vinegar might be a quick and easy fix for your Ca buildup issue. Worth a shot, if you ask me. I bet your plants are enjoying that Ca from your well water (so long as its not TOOO excessive of course).