Is Reverse Osmosis necessary?

[Saskafarian]

Check the link in my sig about a full pH swing, and the benefits it brings to hydro and cannabis. You *want* the swing in the root zone. If you don't get a full swing as your media dries out, I don't believe you can reach peak quality. With 'roots-in' hydro, the root zone swing is fully controlled by your nutrient solution.

I've read that link before, along with your other threads linked in your signature. Very fine work indeed.

I appreciate all the work you've done on your threads. I'm trying out an STS protocol based on information from that thread. I'll report on my findings if I feel they add any insight to the information already posted.

I don't believe your views on PH swing are pertinent to this thread though. The grow parameters set by the original poster are drain to waste coco. I can see a possible use for your ideas in a recirculating system although I have no experience with that format.

Happy growing!

 

[Douglas.Curtis]

Ty, appreciate it and hope the info works as well for you as it has for myself and others.

I don't believe your views on PH swing are pertinent to this thread though. The grow parameters set by the original poster are drain to waste coco. I can see a possible use for your ideas in a recirculating system although I have no experience with that format.

Regardless of media, I believe it's the root zone which matters most. Even with DTW coco, you'll still want a pH swing/variance in your nutrient solution for full effect. The more ppm you have, the larger the pH effect variable becomes.

R/O, or close to it, is going to give you the least pH variance. This will allow the greatest pH swing with whatever nutrient line you're using. As you can imagine, the more buffered the nutrient, the less I'm a fan of it.

Can't get it super clean... without that full dang pH swing... doowop, doowap, dowaaaaaaah! Sorry, heh, it suddenly sounded like a commercial jingle. lol

 

[Broggemann]

Bro, I thought about this already a couple days ago but didn't want to be rude, but now I can't hold back anymore.


You proved multiple times in this thread, that you don't have a clue what you're talking about. Please, stop it...

Regardless of media, I believe it's the root zone which matters most. Even with DTW coco, you'll still want a pH swing/variance in your nutrient solution for full effect.

Wrong. You still don't know about the difference between alkaline and alkalinity and this is what determines your medium pH.
Even the ratio of ammonium to nitrate has a much bigger impact on your medium pH, ESPECIALLY in R/O.
The pH of your nutrient solution doesn't do much, ESPECIALLY in R/O.
And, last but not least, you definitely don't want any "pH swing" in coco in your rootzone.


Please, do some reading, people provided you with all the links you need.

 

[Douglas.Curtis]

Wrong. You still don't know about the difference between alkaline and alkalinity and this is what determines your medium pH.
Even the ratio of ammonium to nitrate has a much bigger impact on your medium pH, ESPECIALLY in R/O.
The pH of your nutrient solution doesn't do much, ESPECIALLY in R/O.
And, last but not least, you definitely don't want any "pH swing" in coco in your rootzone.

Wow, it sounds like I didn't explain things fully and you're lost.

the pH swing happens because the plants are using the nutrients within the r/o solution. Yes, different elements affect pH differently, but what's used with cannabis is generally a pH down. When plants use this up, the pH goes back up.

ANY water with buffering elements in it (well/tap/whatever-unfiltered) is going to speed up or slow down this pH change. With r/o you're working with a KNOWN source. You KNOW what's going to happen. With nearly any other source, you're going to be guessing... and it will often change from season to season.

Yes, I'm quite aware what alkalinity and acidity are, and yes you still need to vary the pH of your input solution with coco for best results.

Hopefully this clears things up for you just a bit.

 

[Saskafarian]

I sent an email to Canna asking if I needed to add Cal Mag to RO when using their nutrients. Their reply may shed some light.

"Hello XXXX,

Thanks for the question, in regards to adding Cal-Mag to RO water there are two paths that can be taken to address this.

First, indeed RO water should be "improved" before adding the nutrients.

Adding cal-mag does indeed work. However, what we are looking for is adding some hardness back to the water to limit/prevent RO water to absorb the calcium and magnesium from the nutrient to harden itself effectively making those elements unavailable for the plants.

The best way to achieve this is adding these elements in Carbonate form, while most Cal-Mag products provide these in the Nitrogen form (Calcium
and Magnesium Nitrates) which provides more Nitrogen than is needed.

Feeding with higher Nitrogen than needed can cause plants to accumulate Nitrogen, in the Nitrite form, which is known be carcinogenic along with promoting vegetative growth, making the flowers having more leafy material than desired.

When using a Cal-Mag, usually 50-100 ppms will work fine.

Some Cal-Mag on the market have Carbonate based Ca & Mg, or low nitrogen to calcium ratios. If these are available in your area, they should be favored instead of regular, cheaper, formulations.

The other fastest, cheapest, more efficient and convenient way is simply to add back "normal" tap water into the RO water. This provides the hardness back to water more inline with water's natural chemistry. Target 50-200 ppm.

This is the best course of action to take, unless the tap water would also contain undesirable contaminants like heavy metals or extremely high levels of sodium, which is often present in water of areas close to the sea or places where the ground is contaminated with industrial by products, as can be found in areas near mining or Bitumen / Petrolium extraction (like we see in Northern Alberta).

This is faster and has as a benefit to reduce problems associated with the handling of the RO filters waste water. Which is often an issue in large scale operation that are not connected to municipal sewage or where regulations severely limit the content of waste water.


I hope this answers your question well, if not do not hesitate to contact us again, you can reach us directly at [email protected]


Have a great day,

CANNA Canada"


This answers the question for me without a doubt. The manufacturer of my medium and nutrients says not to use straight RO water.

Case closed

 

['Boogieman']

I just tested my water and it's ph is 7.3 with 120ppm's and has a calcium to magnesium ratio that is roughly 3-1. Also my water has small amounts of iron, manganese, and sulfur. I grow in soil outdoors and mix my water with rain water. I just wanted to add those details.

 

[Douglas.Curtis]

However, what we are looking for is adding some hardness back to the water to limit/prevent RO water to absorb the calcium and magnesium from the nutrient to harden itself effectively making those elements unavailable for the plants.

Thanks for sharing this, it's rather interesting.

So calcium and magnesium, when exposed to pure water, will combine? and become unavailable to plants. This brings up the question of whether cannabis still absorbs this 'unavailable' content, like it does heavy metals and other unavailable materials.

Is this specific with Canna? Does it show up as a precipitate? Very interesting.

If it's universal, I'm still leaning toward preferring refined calcium/magnesium coming out of my nutrient solution, to 'whatever' comes with tap/well water.

 

[mean mr.mustard]

Not necessary.

I think necessary still means what it used to...

 

[heatherlonglee]

If you want to be a lazy grower yes RO is necessary to eliminate almost all problems with water. I like RO water myself.

I'm not so sure about this above post from Canna? My nutrients are chelated and I'm also using Humics. I should've taken Chemistry several years instead of none. lol

When you add your nutrient into RO water you first just add a small bit 10% and let that mix throughout the solution; then you add the rest of your nutrients to be mixed/dissolved. If you just dump the entire nutrient directly into the RO water all at once you will likely get precipitate; I believe this is what the above post from Canna is trying to say in a long way out round of way?

To further explain. If you were using MaxiGrow as your base and only nutrient and not using any Cal/Mag you'd be just adding the MaxiGrow directly to your RO water. If this was the case; again if you just drop the entire MaxiGrow in the RO it'll precipitate. Add a little MaxiGrow about 10% then mix and wait 20-30 seconds; now mix in the rest of the nutrient you'll get less precipitate. When adding nutrients to RO water what you're trying to do is not cause a really quick fast PH swing from dumping in the entire nutrient at once. It's pure water with no alkalinity so it's ripe and ready for a PH swing until it's gotten some minerals dissolved into it. This quick fast PH swing is what will cause the precipitate and then possibly unabsorbable nutrients that this Canna email has butchered explaining; I did my best or something like that.

 

[LostTribe]

If you want to be a lazy grower yes RO is necessary to eliminate almost all problems with water. I like RO water myself.

I'm not so sure about this above post from Canna? My nutrients are chelated and I'm also using Humics. I should've taken Chemistry several years instead of none. lol

When you add your nutrient into RO water you first just add a small bit 10% and let that mix throughout the solution; then you add the rest of your nutrients to be mixed/dissolved. If you just dump the entire nutrient directly into the RO water all at once you will likely get precipitate; I believe this is what the above post from Canna is trying to say in a long way out round of way?

To further explain. If you were using MaxiGrow as your base and only nutrient and not using any Cal/Mag you'd be just adding the MaxiGrow directly to your RO water. If this was the case; again if you just drop the entire MaxiGrow in the RO it'll precipitate. Add a little MaxiGrow about 10% then mix and wait 20-30 seconds; now mix in the rest of the nutrient you'll get less precipitate. When adding nutrients to RO water what you're trying to do is not cause a really quick fast PH swing from dumping in the entire nutrient at once. It's pure water with no alkalinity so it's ripe and ready for a PH swing until it's gotten some minerals dissolved into it. This quick fast PH swing is what will cause the precipitate and then possibly unabsorbable nutrients that this Canna email has butchered explaining; I did my best or something like that.

In 20 years of using RO water and straight Hydroponic applications I have never seen my Botanicare line precipitate. I dump in up to 150ml at a time into straight ~005ppm RO no problems.

I always run between 3-5ml/gallon CalMag with RO. I always add this first and all at one big dump. No sitting No waiting No BS.

I am now experimenting with Canna Coco bricks (used bagged canna way back when it first came out) no problems and easy growth. Feeding on a timer 3x daily lights on w ~5% run off in DTW. So far its looking fine.

 

[Douglas.Curtis]

My experience is the same as yours, LostTribe, though I do not use cal/mag.

The only time I've seen hydro nutes precipitate anything, is when I've used them with a few specific water supplies. No idea what was in the tap water, but you could see it lock stuff out.

 

[f-e]

I didn't hear anything about precipitation. They're saying a plant can't get every last bit of food out of the solution. Cleaning your solution of all food, until it's RO standard again.

You have to accept that the run-off is going to contain something. It can't leave in a pure state, it just won't give up that last little bit. So if you use RO and feed, some of your feed is lost.

We can influence what the run-off leaves with. Knowing what it will not let go of, helps us add a bit more of that thing. Ideally we could add something to increase water hardness, that our plant doesn't even want.

This gets a bit tricky now, because maybe you don't have run-off. Or perhaps you have evaporation that leaves chalky deposits. So maybe you want carbonates, or maybe you don't. The general advice is to add some hardness to stop your RO leaching hardness from your feed.

 

[heatherlonglee]

When you add your nutrients in parts you're already adding a little at a time then adding more.

 

[Loc Dog]

I saw a number of people mention cost of RO. It is $30 and lasts for years before needing filters. I would not drink tap/well water. They are finding bacteria and poisons from apple farms that used to be in my area.