Tap vs Filtered Water

[demoreal]

I was tought pure water has an alkalinity close to 0 ppm.
I beleive the pH of RO water is not important.
I stand by that 100%.

You think you can lead me to an article to read that states otherwise?


(I do stand corrected stating RO is not unstable, that was a wrong statement, what I ment is to stabalize your res after adding the nutrients)

[Rusty Trichome]

Smell your tapwater. If it smells like chlorine, let it sit out uncovered overnight. If your locals used chlorine gas to kill the bacteria in the water, it should outgas overnight. If they use a solid form of chlorine, the smell will remain, and the water should likely be filtered.

Most tapwater is fine once properly ph'd, and can be used with no adverse effects. If there is no need to buy a R/O system or Britta filters, why do it? Why take the crap out of your water, just to have to replace the crap later? (CalMag Plus, for instance) Especially if unnecessary.

Ph'ing R/O water has no effect on ph pen probes. I've used them for years with my coral and saltwater fish tanks, which is a sensitive enviornment and does require R/O'd water.
You can not store the probes in direct light, or in tapwater, because the tapwater will form algae and the algae will skew results. (and gum-up the probe) An acid or a base is recommended for storage. (too harsh for bacteria and algae to get a foothold)

You can also look online for your local water conditions and ph. For instance, if in Phoenix, Google "Phoenix tap water quality" or "Phoenix municipal water quality report" or something along those lines.
Here's what my locals say about my well water online...(no, not Phoenix, lol)
"Characterization. The character of the groundwater varies from calcium-magnesium
bicarbonate to magnesium-calcium bicarbonate. The quality of
the groundwater is suitable for all beneficial uses. TDS concentrations range
from about 155 to 540 mg/L, with an average concentration of about 330
mg/L. Fluoride content ranges from 0.2 to 0.9 mg/L and averages about 0.4
mg/L. Boron content averages about 0.1 mg/L."

Mine averages near 380-390 mg/L. (saltwater aquarium test kit)

I have never used filtered water for my ladies, but I don't consider my water unusable, either.
Curious though...for those in soil, what does filtering your water do...specifically? (if you are filtering more than chlorine) As soon as you add the water to the medium, your TDS skyrockets, no?

[WashougalWonder]

RO PH does change for a period of time after released to the atmosphere, and I cannot find the article where I learned that. After reading that article I tested my RO water fresh out of the pot and after sitting 24 hours in a plastic bucket in the dark at room temp.

Initial PH was 5.5. 24 hours later it was 6.0, 48 hours later it was 6.0.

It is my understanding that the loss of certain salts effects the osmolarity of the water and makes it unstable and it wants a carbon atom somewhere, which it gets from the atmosphere.

Also, Rusty is right, if you can use tap water, do it so you don't have to add s$it back in. I have to RO because my water has such high iron content it stains porcelain. We get acid rain at times, so that is out. I have to add back the cal/mag and then balance my PH back up to 6.5 or so. I only use the drop method of PH test. Do not test the effluent PH.

Everyone has different water. You will have to tailor to your supply.

[demoreal]

RO is the best thing I ever gave my plants. The crap that is in the water is in a crappy form for the plants to drink. I would much rather give my plants something in a form they can drink with ease.
I think you all are misunderstanding me. The pH of the RO is not very important if the alkalinity is close to nothing.
Anyway, just find me an article about why pH of RO is important, not about stability stuff.
If you feed your plants RO you will notice the runoff pH is the same as the medium pH, no matter what pH the RO is when you feed. Try it out.

[khyberkitsune]

"The crap that is in the water is in a crappy form for the plants to drink."

Not necessarily. Most of the crap in water is too large molecularly for the roots to allow to pass through the membrane, and almost every nutrient for plants (minus nitrogen) is water-soluble and already in an ideal solution. Calcium, magnesium, etc., are all pretty much water-soluble and bioavailable. Of course, these levels vary greatly by city and thus you must eventually figure out the levels between various nutrients. While most nutrients for hydroponics are balanced and buffered for use with RO water, many people find themselves using off-use solutions (Florikan Dynamite is what I used for flowering once in hydro, and it worked GREAT minus clogging up everything) and thus the "grab-everything" nature of RO water will cause massive swings depending upon what it 'grabs' and binds with.

Also, People using *JUST* RO water are doing it only slightly wrong. You have to pre-treat water before running it through RO. Pretreatment is important when working with RO and nanofilters due to the nature of their spiral wound design and picometer-thick meshes. The material is engineered in such a fashion as to allow only one-way flow through the system, and as such, the spiral design can't allow for backwashing with water or air friction to scour its surface and remove solids. Because built-up garbage cannot be removed from the filter surfaces, they are highly susceptible to fouling (loss of production capacity). Therefore, pretreatment is a necessity for any RO or NF system. Best bet - start with a loose Brita or Pur filter, then push it to RO.

Again, Your Mileage May Vary. If you've got excellent low-PPM water from the start, you have not much to worry about, and your pH should be stable through all stages of purification. If you have a bunch of salts ions in your water and the water has been buffered to neutral, the second you remove all of that garbage, you're going to have acidic water due to the ionic imbalance.

[demoreal]

tfc membrane systems come with the carbon pre filter, the clorine in the water will ruin it.

so that question.
Why is the pH of the water important if the alkalinity is close to nothing?

[Rusty Trichome]

Anyway, just find me an article about why pH of RO is important, not about stability stuff.

Hmm...I wonder if I'm reading this wrong then:

"And did you know that it is useless to measure the pH of RO-water or demiwater? Both demiwater and RO-water do not contain any buffer ions. This means that the pH can be as low as four, but it can also be as high as 12. Both kinds of water are not readily usable in their natural form."

Ph and Alkalinity

[demoreal]

I am asking things wrong. The question I have and do not understand is this.

Why is the pH of the water important if the alkalinity is close to nothing?

that is what I want to know.
I do not know if I fully understand what you put in quotes. Does that answer this question?

edit: it seems to support what I think

[khyberkitsune]

"Why is the pH of the water important if the alkalinity is close to nothing?"

Ahh, I get what you're saying. Time for the pool boy to come to the rescue! (Yup, did pools in Plano and Dallas, TX.) First, there's Alkaline-Earth and Alkali metals.

Alkalinity in water solutions almost exclusively refers to alkaline metal content. It has practically nil directly to do with pH, but it does affect it. Alkaline solutions are always basic, yes, but alkalinity is a separate test from pH altogether. Calcium and Magnesium are alkaline metals. This also imparts different chemical properties upon the nutrient solution which are better described by a 300-level college professor than myself. Such ions within certain balances will cause acidic conditions, though other balances have been known to cause suddenly basic conditions. It's a whole mess involving Newton's Third Law that even I am not qualified to explain. That's 600-level stuff.

Then there's Alkali metals, sodium, potassium, and (VERY RARELY) hydrogen (usually found as a dual-atom stabilization in nature, and often bound with oxygen to make water,) being the most typical ones involved in plant growth. These are not as often found (in fact very rarely found in nature) in a pure plant-usable form.

Typical ion filtration uses hydrogen-ion filtration with carbon filters - this produces almost soda water (you're only missing the gas/liquid ratio + pressure to have soda water) and this makes it very unstable. You must let it stabilize with the atmosphere, then add nutrients. Differing pH levels will cause lockout not only for absorption but also for proper solubility in water itself, so it can cause deficiencies as well.

EDIT: Think of it like this, as this is how we do in the pool industry; pH is POTENTIAL HYDROGEN. Alkalinity is the alkaline and alkali metal/molecular concentration. This has effects upon algae growth and such. Had to call my brother's father for clarification on this, as we both work together on making new hydro systems. Nice to have men with a common goal and engineering background to work together - he's the one that taught me about pools.

[Rusty Trichome]

Carbonate hardness comes to mind when discussing alkalinity and ph, at least in coral aquariums. Might help here. Here's a definition:
" Carbonate hardness also known as KH, refers to the concentration of bicarbonate (HCO3-) and carbonate (CO3--) dissolved in water. Hydrogen carbonates are easily soluble in water, while carbonates virtually insoluble. The level of carbonate hardness thus depends on the amount of dissolved hydrogen carbonates.

Carbonate hardness affects plant growth to a greater extent than does the level of non-carbonate hardness. Plants can dissolve carbon dioxide out of hydrogen carbonates and use it for photosynthesis."

So, there's interraction between the metals, minerals, bicarbonates and carbonates in an ion power struggle for control of ph. Good thing you don't have to add nutrients, and really make it interesting, lol. Just kidding, but I sure do appreciate the simplicity of growing in soil. :jointsmile:

After keeping saltwater tanks, and all the care and coddling, testing and adjusting (and cost) that goes along with it...the last thing I want is to do is overcomplicate cannabis, too.