Water Question, RO, Distilled, pH

This is really getting good. Great Info here.
Illegal Smile, please keep us posted as to what happens.

FilthyFletch, thanks so much man, I WILL definitely give you credit for your experiments. I already have the CD sold.

hope this gets some feed back because my ro machine brings my ph down to 4.3 and most people i talk to say theirs is in the mid 5s

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Your R/O machine isn't working properly then. The whole point of a R/O system is to provide you with near pure water. Pure water has a PH of 7.0. My R/O system gives me water at a PH of 7.0 and a TDS of 15ppm, and my source water is well water at a PH of 8.2 and a TDS of 120ppm.

As for the PH stability of tap vs. RO. Logically, it makes sense that tap water is more PH stable due to the fact of having more of a buffer (ie. calcium, etc.). I use AN 3 part with R/O water and I end up with a PH of between 5.2 and 5.8 depending on what ratio of micro, grow, and bloom I use, so sometimes I have to add a little bit of Potassium hydroxide to get my PH to 5.8. I don't have a problem with PH flux because I run a drain to waste setup, though the PH will still slowly raise about .1 each day. I usually PH to 5.8 and end up with a PH of 6.3 by the time the solution is used up a week later. When I was running a recirc setup, I got horrible PH flux (PH rising .5 or more per day), and that's one of many reasons why I ditched recirc for drain to waste, and my plants have thanked me.

In my experiment I did get some drift DOWN in the tap water. In 4 hrs it went from 5.7 to 5.3. The distilled water remained at 5.7. I'm guessing this is because I practically hammered it down to 5.7 to begin with, I overshot the mark and there was some residual lowering still to come after it hit 5.7.

I can conclude that I can't use my tap water, wish I could. I still check pH once a day and it will be at 6.5 and I'll lower it to 5.7 or so. Day after day. But the plants don't seem to mind. By the way I started nutes on day 6 and it didn't seem to affect the pH cycle at all and I was surprised at that.

Update: at 8 hrs the tap water has fallen to 5.3 and the distilled to 5.6. In my tank they drift up and the only difference is the tank has seedlings in it.

Illegal im confused by your assumtion of your tap water not being good to use as the data your giving would lean the opposite way. Your tap water is more resistent to flux which is a good thing while your comment on your RO means it takes very little for the ph to jump or lower then you back this up with the tap water actually dropped slightly which would help compensate any jump from nutrient salts fed back by plants so by your posts your tap would be much better then your RO for stability..

FilthyFletch said:

Illegal im confused by your assumtion of your tap water not being good to use as the data your giving would lean the opposite way. Your tap water is more resistent to flux which is a good thing while your comment on your RO means it takes very little for the ph to jump or lower then you back this up with the tap water actually dropped slightly which would help compensate any jump from nutrient salts fed back by plants so by your posts your tap would be much better then your RO for stability..

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My reasoning is based on what I have read that says buffers aren't just generally buffers, tending to hold pH wherever you set it. Instead my impression is buffers tend to hold PH to a certain range. So my water doesn't resist fluctuation, just fluctuation away from 7. If you want your pH in a 5.5-6 range you want a buffer that, because of its chemical properties, tends to hold pH there. But since mine seems to want to hold it to 7, I'd be fighting an uphill battle to keep it under 7. That's what I meant when I said your water is very fortunately a buffer right in the range you want. At least that's what I'm getting when I try to connect all these dots, but who knows. The more I try to learn about pH the dumber I feel.

Roseman said:

You guys really need to read what is posted here, especially from Filthy Fletch.

https://www.rollitup.org/hydroponics-aeroponics/230241-water-question-ro-distilled-ph.html

It is about whether PURE, Filtered water is better than water with lots of minerals in it, and controling spiking pH levels.

I am beginning to think RO or Filtered or Distilled water is NOT best for pH control........maybe.

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Quote is from another post.

RO water is not good for pH control. "Pure" water is very soft and unstable. Since there are no minerals which act as buffers, pH changes can be drastic. Water needs something to buffer it to protect from pH changes, if a good nute is being used it will provide some buffering, but as it gets used and absorbed the ability to buffer diminishes. Fish stores sell chems just to buffer water and keep the pH stable.

PS this is just some info from my fish tank days.

Illegal Smile said:

My reasoning is based on what I have read that says buffers aren't just generally buffers, tending to hold pH wherever you set it. Instead my impression is buffers tend to hold PH to a certain range. So my water doesn't resist fluctuation, just fluctuation away from 7. If you want your pH in a 5.5-6 range you want a buffer that, because of its chemical properties, tends to hold pH there. But since mine seems to want to hold it to 7, I'd be fighting an uphill battle to keep it under 7. That's what I meant when I said your water is very fortunately a buffer right in the range you want. At least that's what I'm getting when I try to connect all these dots, but who knows. The more I try to learn about pH the dumber I feel.

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Illegal, what nutes are you using? Just for purposes of determining acidity or alkalinity?

tSunami13 said:

Illegal, what nutes are you using? Just for purposes of determining acidity or alkalinity?

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I'm using AN Micro/Grow/Bloom now and for this test, but I plan to change for the next grow. I'm not disagreeing that water needs a buffer, just that a buffer is a buffer is a buffer and it's all good. Using water that is buffered to the wrong Ph range seems bad. It also seems that starting with zero water is the best way to work toward getting it buffered correctly while tap water sounds like a crap shoot. Maybe I'm wrong that's just how it seems with what I've absorbed so far.

I keep hearing that if the water is not buffered the pH will swing around. But I don't understand what engine drives that swing if there is nothing organic going on. If there is something going on then good nutes ought to be acting as a buffer. I have had many growers say that they start with RO water, add nothing but nutes, and keep pH stable. How are they doing it? It is confusing. I don't see why there isn't a product out there called pH 5.8 Buffer Solution. If there is some mix of unknown stuff in some tap water that helps stabilize pH then why can't we synthesize that if it is lacking? I'm just having a hard time buying, "use tap water, it has lots of impurities that you need."

Update if anyone is still following this: my little experiment is at 24 hrs and there is no further drift in either water after the initial drop in the tap water which I assume was due to all the pH down kicking in.

Illegal, I don't know the science behind buffering or anything like that. I learned the stuff from being into fish. Also, I have noticed that my pH differs depending on what it comes out of. I've had 8.0 water out of my hose, 6.0 out of the tap. Plastic's and other material can affect the pH. I know with the AN nutes I have used, the pH has been very consistent, enough where I don't check it daily. I use glass jugs for mixing and holding water, just trying to avoid contaminates that mess with the pH TDS reading. It's the calcium and magnesium and other minerals that buffer the tap water. If you have some friends that have salt water fish tanks ask them about buffering. Hopefully your pH settles down.

Illegal Smile said:

Update if anyone is still following this: my little experiment is at 24 hrs and there is no further drift in either water after the initial drop in the tap water which I assume was due to all the pH down kicking in.

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I'm following.....very interested too.

So after 24 hours, there's not much difference?

tSunami13 said:

Illegal, I don't know the science behind buffering or anything like that. I learned the stuff from being into fish. Also, I have noticed that my pH differs depending on what it comes out of. I've had 8.0 water out of my hose, 6.0 out of the tap. Plastic's and other material can affect the pH. I know with the AN nutes I have used, the pH has been very consistent, enough where I don't check it daily. I use glass jugs for mixing and holding water, just trying to avoid contaminates that mess with the pH TDS reading. It's the calcium and magnesium and other minerals that buffer the tap water. If you have some friends that have salt water fish tanks ask them about buffering. Hopefully your pH settles down.

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Good Post, I tred to
REP you and it wouldn't let me give you anymore.

tSunami13 said:

Illegal, I don't know the science behind buffering or anything like that. I learned the stuff from being into fish. Also, I have noticed that my pH differs depending on what it comes out of. I've had 8.0 water out of my hose, 6.0 out of the tap. Plastic's and other material can affect the pH. I know with the AN nutes I have used, the pH has been very consistent, enough where I don't check it daily. I use glass jugs for mixing and holding water, just trying to avoid contaminates that mess with the pH TDS reading. It's the calcium and magnesium and other minerals that buffer the tap water. If you have some friends that have salt water fish tanks ask them about buffering. Hopefully your pH settles down.

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My pH is not a problem. I adjust it once a day and at the extremes it is never out of bounds. I'm interested because it is interesting. I guess I "am" a scientist just not a chemist and it is hard for me to buy into the theory that the best water is that which has unknown amounts of unknown substances in it to act as buffers. The real (or wannabe) experts at the major nute companies swear their products are designed to buffer pH correctly in the range they know (wink) we want. Seems logical they would do that. So I guess the question is, since either kind of water is going to get seriously altered chemically anyway, which is better as a starting point. And I guess that boils down to: can dissolved solids in tap water improve upon the buffering planned into nute (if indeed it is there)?

I guess if I knew more about the chemistry of PH buffering and if I could test my tap water not only for ec/ppm but for what exactly is there and in what amounts, I might go with tap water. But doesn't it seem a little "shot in the dark" to you? I'm frankly surprised you all are embracing it, but then I have been on a trip of discovering that we don't really need to have this or that thing that we have been told we need and maybe zero water is in that category. Plus Cervantes is pro RO water and pretty negative about tap water (and that's the freaking Bible!). So the bottom line is.... I don't have a clue but am stumbling ever forward regardless. Sorry for the long ramble, I smoked some of the speedy stuff.

My first grow I didn't have an RO. By the end of the 2 month cycle my hydroton was white with all the crap that was in the water had built up on them. I had hard water crap on the top of my DWC buckets that flacked off any time I touched it. It even built up on the walls of the room (from the BBs)

This grow I got an RO system for my flood and drain tables. I like to start off with pure water so I know exactly what is going into my soup. My RO brings my water to a Ph of 4.7 and 3-4 PPMs. My tap water starts off around 350 PPM and the Ph varies from 6.8 - 8.4 Again, I like to know what is going into my soup. My AK47 needed more Mg, so I add just enough Epsom salt to correct the problem, same amount every time.

I also like the fact that I only need drops of Ph up or down to get to 5.8 as opposed to TABLESPOONS with tap water. This also helps to keep my PPMs down for more important things.

I think the plants themselves have a big part on the fluxuation also. I have 4 big moms on a 2x2 tray. For the longest time my soup would climb to 6 - 6.4 after two days. The past few weeks, the Ph hardly moves! I mean, I have to top off gallons into my rez a week later and the Ph is the same. That being the exception, all my rezes need to be corrected after two days. Some times they get a little out of wack and I have to correct once a day to get back under control.

I have no idea if this holds water, but I have always figured if my water is 6.2 and I correct it back to 5.8, the first time my table floods, the Ph will shoot back up some because the hydroton in my pots has a Ph of 6.2
Again I don't know if true, but when I correct I bring it lower than 5.8. More like 5.3 and after the first watering it will be where I want it.

By the way in my experiment, both water samples are holding steady after 48 hrs. I don't expect them to move anymore. The only real finding is that it took a ton of pH down to get the tap water from 7 to 5.7, and very little for the distilled.

From my experiences the RO water will fluctuate more then the tap water. There is nothing in the RO water to keep it stable. There is nothing wrong with RO water other then it does become the most expensive element in growing. I am happy to see everyone reap the rewards of a good grow, but all the bashing of some nute companies for being expensive is bologna (not the bubbleheads bashing stuff but many others). I know water is very important, but to make it the most expensive additive is silly. Tap water 1000 gallons 5-10 bucks, 1000 gallons of RO water just say 50 cents a gallon your at $500.

Hey Illegal, you should be able to contact the local water department and get water quality readings, so you can know what is in the water. Of course it will differ from your faucet, being the pipes it goes through to get there are breaking down over time adding stuff into the water.

I paid $159 for an RO unit that can make 50 gallons a day with no need for any filter replacement for a year. That's a penny a gallon for the first year then less after that.

Illegal Smile said:

By the way in my experiment, both water samples are holding steady after 48 hrs. I don't expect them to move anymore. The only real finding is that it took a ton of pH down to get the tap water from 7 to 5.7, and very little for the distilled.

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From my experiences with fish tanks, the tap water will hold the pH longer then the RO water. Just think your RO cup is very low PPM water with acid in it, as soon as something acts with it, the pH will become unstable. The tap water cup that took a lot of pH down has all the minerals in it to "buffer" the acid and therefore will not fluctuate as much when other things are added. Take your RO cup for example, put one drop of an alkaline substance in it and watch that pH swing. Put the same drop in the tap water cup and it the pH won't do much. That should really show that nothing is "buffering" the RO water.

EX.. RO water 7.0 pH, add one drop pH down say you get 6.0 pH, now add one drop pH up and shouldn't you be back at 7.0 pH, basically canceling each other out? In the sense nothing is buffering the water it is free to change rapidly and is easily affected by outside influences.

I just was looking at my fish tank chems and for me to lower the pH I would use a Neutral 7.0 pH buffer made up of phosphates, and then add an Acid buffer in its ratio to lower the pH. Most of the stuff though is buffers with very little acid added to drop the pH but uses the buffers to hold it steady. Just imagine putting in clean RO water in a fish tank and then they decide to pee in it, something is going to happen to that pH. It's all the buffer stuff that keeps the pH steady so when fish dirty up the water it doesn't drastically change the pH.

What kind of RO unit are you using? I worked at a big coffee shop chain and the RO unit there was a 4-1 ratio. In other words it took 4 gallons tap to make 1 gallon RO. This RO unit was on the extreme end, and not very environmental friendly.