Water, oh! water!

[OrchidIsa]

I'm posting this today, hoping someone can help... I'll try to explain myself the best I could so the details are complete. Feel free to ask if something seems blurry

So. I don't live in a place serviced with city water so I have a well. I got that water tested a few years ago (standard evaluation for human consumption) to know what was its content. It appeared that there was a lot of salts in it. Like 550 tds and more (tested it 5 minutes ago, only 380 tds!!). The usual pH is around 9 (just tested it too). It changes a bit over the year.

Here are some of the results of that analysis:

Boron 0.600 mg/L
Cadmium <0.0010 mg/L
Calcium 1.47 mg/L
Chrome <0.0050 mg/L
Copper <0.0030 mg/L
Iron <0.10 mg/L
Potassium 2.66 mg/L
Magnesium 0.63 mg/L
Manganese 0.003 mg/L
Lead <0.0010 mg/L
Sodium (Na) 202 mg/L
Zinc (Zn) <0.01 mg/L
Total hardness 6 mg CaCO3/L

I wanted to use this water for my orchids so I got a RO system, knowing there was way to much salts in it. Only 20 ppm of salts (in total) tested after passing through the system. I'm always ajusting the pH around 6.5 with citric acid before watering.

The thing is I know there is methane in the water (the guy at my local water filtration store told me it's common here, confirmed by bubbles when I get a glass of tap water). There is a pink gooey gelatin-like forming in stagnant water (like in the toilet tank), thing that disappear with some chlorine-bromine pucks put in the tank. Bacterial, then ? I suppose...

When I was using the RO treated water, putting some fertilizer (like PlantProd 25-10-10 for example) in it would sometimes create some bubbles (effervescence). A few seconds only, then nothing.

I actually use rain water (collected from gutters of the house), city water from my office, melted snow in winter. So much hassle to collect! I grow paphs, phrags, sarcos, aerangis, neos... Need like 10-12 gallons of water per week approx.

Ok. So the questionS are:

- Can I use that RO water, with those remaining 20-23 ppm, knowing there is still (very) few sodium in it?

- Can I use it even if there is methane in it?

- Why would some bubbles form (for a few seconds) when I add fertilizer?

Somebody has answers for me?

Thanks for your help

 

[orchid527]

Let me make a semi informed guess regarding your questions. Yes, you can use this water. The methane should not make any difference. The bubbles are likely CO2. The reason I say this is because I have hard water like you, I have an RO system that I built myself and I am a chemist. That said, I could be wrong about the CO2. Mike

 

[OrchidIsa]

Thank you Mike for these answers! Very appreciated

 

[troy]

Mike I would like to know how you built your ro system, if you could explain, it would save me lots of money, I go through 50 gallons a week, thank you!!!

 

[orchid527]

Troy

This is how I built an RO system that suits my needs. The first thing was to buy one of the cheap commercial units from one of the big box stores. That unit has three cartridges mounted on a plate and a small pressure tank that fits under the sink. The first cartridge is a filter for the RO membrane. The second cartridge contains the RO membrane and the third cartridge is the same as the first, but is used to filter water coming from the small pressure tank. The reason I purchased this unit was so that I could buy cheap replacement parts. However, as sold, these will not work very well for our purposes for several reasons. The volume of the tank is too small, the tank takes too long to refill, and the TDS will be too high. The reason the TDS will be too high is that the effectiveness of the membrane is dependent upon the pressure differential across the membrane. So, when the tank first begins to fill and there is little back pressure, the TDS will be very low, but as the back pressure increases, the TDS begins to climb. The worse possible case is where you pull off small volumes of RO water and the tank is always refilling with minimal efficiency. The average TDS of your RO water in this case could be > 50ppm.
The first thing I did to customize this system was to remove the tank and re-plumb the system to use only the first two cartridges. I then mounted the plate on the wall in the utility room where my hot water heater and furnace are located. I purchased a plastic 30 gallon drum and routed the line from the RO cartridge directly into the drum. We have softened water on the hot water lines, so I tapped into the line just before the water heater for the feed into the filter for the RO system. The waste water was routed to the drain for the furnace/AC. I purchased a 120v diaphragm pump for about $100 to pump finished water from the drum and mounted it on the wall. When I anticipate needing some RO water, I open the valve that feeds water into the filter and begin collecting water into the drum. It takes about 8 hours to collect the 30 gallons, but because I have a drop of 60 psi across the membrane and because I use softened water as my source, the finished water is very pure at about 4 ppm TDS. It is very likely that the 4 ppm TDS is mostly sodium, but it doesn’t seem to be a problem with anything I grow. The advantage of using soft water for the source is that the sodium ion is very large and is easily excluded by the RO membrane. I go through about 60 gallons per week and I have been able to use the same RO cartridge for about 5 years. I had a similar setup at my previous home where I used 400 ppm TDS hard water as my source and it worked just fine, but the RO membranes don’t last very long.
I would like to add, that I use this water to mist plants, but I never use it to water them directly. I water plants with a mix of about 5:1 RO water/unsoftened hard water with very low levels of fertilizer. The TDS of my irrigation water + fertilizer is about 100 ppm and the pH is about 6.5 without additional adjustment. This seems to work well for all of the things I grow, even the phrags.

 

[troy]

Thanks!!

 

[Ray]

Orchid527 - can you post a photo of the RO system?

I have used RO for 35 years, and have built and sold systems for over 25, and I have never seen one that resembled what I'm picturing from your description.

Most residential systems have a sediment filter, followed by a carbon filter (or two, if your water supply is chlorinated), followed by the membrane and then a carbon "polishing filter" for taste improvement. That last one is unnecessary for plants, so I recommend that folks not bother replacing them, when they come due.

I sell a residential version, with the 3.5 gallon bladder tank and a faucet, as well as a grower's version (pictured above) without them, so folks can connect them to a storage tank via a float valve to automate collection and refilling.

They all use standard component (and I provide 2 years' worth of replacement filters at no charge). In the long run, RO ends up costing in the neighborhood of $0.03-0.04 per gallon.

 

[Erythrone]

I know that Isabelle used RO water from well water for many months/years. And she suspected there was something going wrong with her orchids. And I suspected that too.

Anybody knows if the pink slime in water is always from bacterias? Could it be a sign of another problem?

And about the "bubbles" she saw when adding fertilizer: Could they be from other stuff than methane?

 

[orchid527]

Ray

I used a Whirlpool system from Lowes. It has a wheerm cartridge in the middle ($50) and 2 sediment cartridges on either side. There is no carbon filter. You can buy the sediment cartridges 2/$39. I purchased the entire system for less than $150, but I don't think they sell this exact system anymore. It sounds like your grower's version would be a good replacement. I used a float valve to automate my last RO system, but for the small amount I need, manual batch filtration works just fine.

Mike

 

[orchid527]

Erythone

I've lived in 3 homes with wells and we always had some kind of bacterial growth in tanks. It ranges from pink slime to rusty, feathery-like growth. All of these wells pulled water from the aquifer that runs down from the east side of Lake Michigan. The wells were more than 150 feet deep, and although they do get recharged from surface water, much of what we pump up has been in there for thousands of years and it is not sterile. It is kind of gross to think we are drinking this, but the reality is that as individuals, we are actually complex biological systems with many different types of organisms growing in and on us.

Regarding the outgassing Isabelle sees when she adds fertilizer. It could be any dissolved gas. If it is methane, it won't cause any problems as this would be present in any natural system where organic material is degrading. If it were hydrogen sulfide, she would know. My guess is CO2, but it could be anything.

Regarding watering with RO water, it is critically important to reconstitute your irrigation water will ALL of the minerals plants need to grow. If you use straight RO, you will see signs of calcium deficiency within a year. If you use calcium nitrate, you will induce deficiency of other ions. I am beginning to believe that addressing this problem by using the Michigan State formulation for RO water is not sufficient. I did this for years after its introduction and eventually my phals, psychopsis, equitants and some phrags started looking like crap. I switched to 5:1 RO/hard tap with plain old Miracle Grow, and the problem went away. This is not a well designed experiment to prove a theory. It is just my best guess and it seems to work.

Mike

 

[NYEric]

Thank you Mike for these answers! Very appreciated

Don't listen to him! I think you are in danger and should drink only fermented beverages, red wine, beer,etc.

 

[Ray]

Ray



I used a Whirlpool system from Lowes. It has a wheerm cartridge in the middle ($50) and 2 sediment cartridges on either side. There is no carbon filter. You can buy the sediment cartridges 2/$39. I purchased the entire system for less than $150, but I don't think they sell this exact system anymore. It sounds like your grower's version would be a good replacement. I used a float valve to automate my last RO system, but for the small amount I need, manual batch filtration works just fine.



Mike

Wow! That is a relatively expensive system to maintain!

For standard RO systems, sediment filters run anywhere from $2.50 to $5.00, carbon filters (I cannot understand how that system gets away with not having one) run about $5-$8, and membranes run about $40-$50.

For folks with smaller demand, I build a manual "counter top" system that can be put away between uses, but the filter replacement cost is a bit higher, because they are encapsulated, throw-away types (as are yours) rather than being in canisters.

As far as nutrition is concerned, I totally agree that you must provide everything, but disagree that calcium nitrate will cause other deficiencies. Certainly, if used alone, you are still not providing lots of other essential minerals, but there is nothing that makes the CaNO3 a problem.

About 5 years ago, I switched from MSU RO to a low P & K derivative, K-Lite. It's a 12-1-1-10Ca-4Mg formula that has roughly the same levels of "minors". I have used it at 25 ppm N at every watering, supplemented monthly with 1 tablespoon/gal KelpMax and 3 tablespoons/gal Inocucor Garden Solution. I can honestly say that my plants have never grown or bloomed better.

 

[orchid527]

Ray

I've been using this for 5 years at 60 gallons per week with the same cartridges. My maintenance cost has been $0. Regarding the problems with using Calcium Nitrate, I believe one of our Canadian members also reported having issues. I suspect in my case, it was just too much for too long. Ironically, I believe the observed deficiency was actually potassium. Again, not a definitive experiment, just a best guess and it seems to have resolved the issue. Mike

 

[gego]

Ray

I've been using this for 5 years at 60 gallons per week with the same cartridges. My maintenance cost has been $0. Regarding the problems with using Calcium Nitrate, I believe one of our Canadian members also reported having issues. I suspect in my case, it was just too much for too long. Ironically, I believe the observed deficiency was actually potassium. Again, not a definitive experiment, just a best guess and it seems to have resolved the issue. Mike

Hi Mike, can you share what was the observed deficiency? Any pic? Not trying to solve the problem, I just want to learn and gain more info. Thanks

 

[Ray]

Ray



I've been using this for 5 years at 60 gallons per week with the same cartridges. My maintenance cost has been $0. Regarding the problems with using Calcium Nitrate, I believe one of our Canadian members also reported having issues. I suspect in my case, it was just too much for too long. Ironically, I believe the observed deficiency was actually potassium. Again, not a definitive experiment, just a best guess and it seems to have resolved the issue. Mike

Either your incoming water isn't all that bad, or you're approaching the reasonable life span of that membrane.

Brandon Tam, who manages the orchid collection at the Huntington Botanical Garden, only uses calcium nitrate in his tap water, and he's winning cultural awards left and right!

 

[orchid527]

Ray

You could be right about approaching the end of life for this membrane. I estimate that I have produced more than 15 K gallons of 4 ppm TDS RO water. I do monitor the TDS, and if it goes up, I'll know it is time to replace the membrane. I also keep loose track of how long it takes to filter a particular volume of water, and if that increases significantly, I'll swap in the unused third filter. BTW, the TDS from the well ranges from 300 to 400 ppm, depending on the season. The water in the late summer and fall is harder. Also, there is little iron and manganese, mostly just calcium and magnesium. This water is softened for all lines in the home except the drinking water, and the softened water has been the source water for the RO unit since its installation.

Regarding, the calcium nitrate issue, I think this deserves more discussion. I'll get some photos and put things together so that the entire story is better documented and more coherent. Probably better to start a new thread.

Mike

 

[Ray]

That fact that you're using softened water through the RO system explains the longevity.

 

[Ozpaph]

Cant you just add back in 5-10% of the well water to the RO water?

 

[Erythrone]

Regarding watering with RO water, it is critically important to reconstitute your irrigation water will ALL of the minerals plants need to grow. If you use straight RO, you will see signs of calcium deficiency within a year. If you use calcium nitrate, you will induce deficiency of other ions. I am beginning to believe that addressing this problem by using the Michigan State formulation for RO water is not sufficient. I did this for years after its introduction and eventually my phals, psychopsis, equitants and some phrags started looking like crap. I switched to 5:1 RO/hard tap with plain old Miracle Grow, and the problem went away. This is not a well designed experiment to prove a theory. It is just my best guess and it seems to work.

Mike

Totally agree wiht you about the importance of such nutrient like Ca and Mg when using RO systems. That's why I almost always add well water to the RO I use. I think Isabelle does that too.

I don't have pink slime in my well water and didn't had even at my previous home. The first time I saw this was at Isabelle's home, so I was not sure it was from bacterial source. Of course I know my well water is not sterile and I don't want it to be I love to think I manage an ecosystem in my growing area, and an ecosystem has much more in it than the plants, insects and spiders we see