Reverse Osmosis Water Management
 

Created to help WaterWitchin, but I thought I'd Nye on a bit, so here's my thoughts:

Pure water is best for orchids. They evolved getting very pure water, whether that be heavy, tropical rains or high-altitude dew.

Reverse osmosis (RO) is a reliable, economical way to provide that, if you do not have sufficient rain collection or snow melt capabilities.

RO, unless you go for a VERY large, costly system, is not an on-demand water supply. A "100 gallon per day" system sounds like a lot, but that's around a cup per minute, and you're not watering much at that rate. Storage of accumulated, purified water is the way around that.

My volume demand is low, so I can produce it a few hours in advance. Most residential systems are supplied with a bladder tank to hold about 3 gallons, but in greenhouse applications where the usage can be quite high on a per-watering basis, it is more common to have an open-air storage tank, connected to the RO system through a float valve.

Small RO systems, like the counter-top one I use, are manually operated. Turn the feed water on, collect the pure volume needed, then turn it off. Residential and grower's systems are typically automated, via the use of a hydraulic cutoff device.

A little bit about RO functioning: water entering the device passes through sediment and carbon filters, then goes into a membrane housing. There, the water flow splits in two: some of the water is pushed through the membrane - only pure water passes, and the rejected dissolved solids are flushed away by the other stream.

Back to the hydraulic cutoff: before water enters the membrane it passes through one side of the cutoff, which is about the size of an egg. The pure water exiting the membrane housing passes through the other side before going to the storage tank.

http://firstrays.com/Pictures/RO/cutoff.png

Assuming the pure water usage is stopped, the bladder tank fills, or in the case of an open-air tank, that fills until the float valve closes. When the back-pressure in that pure water line reaches 2/3 of the incoming water pressure, the cutoff snaps shut, stopping all flow of water to the membrane.

My setup depends on 1 HP Shallow Well pumps... I have a 150-gal-per-day unit, which feeds into a 55 gallon drum (with a float-switch cutoff) The pump turns on when there is a pressure drop (like opening a hose nozzle or running it through sprinklers) The effluent (which is still decent water for most purposes) goes int two 55-gallon drums (the unit produces 1 gallon of pure water to 2 gallons of effluent) The effluent is delivered to the lawn sprinklers - on a timer, again pressure comes from one of those pumps. It is important to have safety switches on the pumps so that when the tank is drained the pump is turned off... running dry will destroy them in short order. The lawn is happy, and the orchids are even happier.

This is a very helpful thread

Thanks for mentioning the flush water ratio..

Off-the-shelf units typically produce 3 or 4 gallons of flush water for every gallon of pure water produced. That can be reduced by changing the flow restrictor on the flush water line. The 1:2 (pure:flush) ratio Roberta mentioned is pretty much the “tightest” I recommend, as reducing the flush water further results in faster fouling of the membrane.

One should do a financial and environmental calculation on that. Membranes cost roughly $50 and typically last about 2 years, but it may be worth tightening down on the flush water more and replacing them more often.

Boosting the pressure and/or temperature of the incoming water also enhances the efficiency. Membranes are rated at 65 psi & 77F right at the membrane. Increasing them enhances the membrane throughput while the flush/effluent flow is unchanged.

As to what to do with the flush water, I like the idea of using it for less-sensitive plants. In her case, the TDS of the effluent will be 1.5x that of the incoming water (TDS in x input/flush = TDS of flush).

When I had my greenhouse in PA, mine went to a small, artificial pond outside. Frogs loved it, and the local birds, deer, etc. - and our dogs - drank from it.

Most folks just let it run onto the greenhouse floor where it helps keep the humidity up.

If you are using RO in your home, there are kits available that pump the effluent into your home’s hot water lines, making the water usage 100% efficient.

Get an inline TDS meter to monitor inlet and outlet water so there's no guessing as to when to replace the membrane.

My head hurts. I'm gonna study this a while, and get back with you.

Okay, is this kit I found on Amazon what you're talking about:

Malida 1/4" Tube Float Valve Kit for RO Water Reverse Osmosis System water filter Push to Connect Pipe Hose Tube Fitting

Then this TDS thing...

HM Digital DM-1 In-Line Dual TDS Monitor, 0-9990 ppm Range, +/- 2% Readout Accuracy

I think that's overkill... I just check the TDS with my cheapie meter, I'm not looking for great accuracy, just change. Actually, the output rate on mine drops very noticeably before the TDS is affected very much. It still works, but slowly until I start running out of day to refill.

If the output rate drops while the TDS is still acceptable, and assuming that the inlet temperature and pressure haven't dropped, your sediment and/or carbon filters are clogged.

Not what I have observed.
I have changed filters and found that the flow rate didn't improve. There's not much stuff in my water - the sediment filter never shows much. The carbon filter doesn't have much to do either. The TDS does increase, but it's subtle... a new membrane puts about 15 parts per million TDS, when it' on the way out it creeps up to close to 30. I wish that the filters were the cause... it's cheaper to replace filters. But I have tried replacing the filters more often, the membrane lifetime is about the same. So no, that's not the issue. I also backwash the membrane regularly, as the manufacturer recommends. The low ratio does cost in membrane life, but I'd rather deal with that than use more water.

Well, the one pictured is less than ten dollars more than a cheapie one (neither of which I own). So for a few extra bucks, this one would be leashed onto something and I wouldn't have to look for the last place I misplaced it. :D But is this the right stuff I found that we're talking about?

---------- Post added at 10:53 AM ---------- Previous post was at 10:42 AM ----------

And the float valve and hydraulic whatchamacallit... do these come with instructions of how to install? I'm not getting how I connect this to my water spigot. Or maybe this all gets put inline with the RO system and the idea is you just keep spigot turned on, like washing machine hoses?

Also as info, when it gets really cold here I have to share that RO spigot with the hose we fill up horse, alpaca, chicken waterers with. So the spigot is single (in a basement utility sink) and has a two way ball cock on it. So when the hose is utilized (through the basement window to back pasture) the RO side gets turned off.

I don't think that would be a big deal if the hydraulic thing and float get hooked in somehow along with the RO tubes. I don't need it to automatically fill up and leave the water spigot turned on all the time. What I need to figure out is how to not have the same mess I had earlier, where I forgot to set a timer and ran 25,000 gallons of water down the basement water drain over a period of almost a week. I want to use it like a "safety shutoff" when I do forget.

This certainly works, I got my float valve at Home Depot, they sell them for evaporative coolers. (They didn't have it at my local store, I live in a relatively cool area, but they carry them at stores that are inland that have hot summers... ordered, and picked up at my local store, no shipping charge) It was totally easy to install in my "receiver" drum.. just drill a suitable hole, A nut to hold the valve in place, a compression fitting to hold the water tube.

This is what I use:
Float Valve

WW - there is absolutely nothing wrong with the "cheapie".

I will be happy to help you install it.

There are 2 flow paths through the auto shut off solenoid. One handles the finished water coming out of the unit, which is the one connected to the float valve. The other handles water coming out of the final prefilter stage before it entered the ro membrane. They should be marked, or at least readily distinguishable by comparing the unit to the illustration in the instructions.

Look at my graphic above. The ports should be labeled “in” & “out”, but I described the connections, as well.

I've gotta get the stuff ordered and here. Then I'll be back with any questions. I'm sure it will be easy install once I actually have the pieces in hand. And a troop behind me to answer questions. Gracias for all the support/help/explanations thus far!

One brand I've installed (Coralife if memory serves) marked the ports "in" and "out", but without marking which side of the system was for product water. But the unit is assymmetrical, so by comparing with the illustration the proper hook up became apparent.

Yes Subrosa... "apparent" being the operative word. You forget who we're dealing with here... ME. :rofl:

I'm the one who had to have remedial training to learn how to operate those push/click connectors to get my mister set up. What a pro I became by the time I got the RO going. :biggrin:

Hahaha! Well that's why friends are for!

Every one I've ever seen has screw heads visible on one side - that's the "pure water" side of the switch.

After the filters you have changed will be cleaned of the materials included in them to be protected(?), the water purity (RO) will be around 2-3 ppm. To have a higher flow at RO output you must use a 300CC Flow Restrictor.

Interesting. Is that kinda like needing a flow restrictor on a drip or soaker hose?

For a fixed chemistry of impurities, a membrane will remove a relatively fixed percentage. Generally, the higher the molecular weight, especially over 100, the better the rejection. Inorganic ions are rejected better than organic ones of the same MW, but we put the water through carbon first to try to trap those (and chlorine, which can degrade the membrane).

Residential membranes are rated using a known concentration of NaCl in water, applied at 77°F and 65 psi right at the membrane, and typically remove 96%-99% of the solute, no matter what the pressure applied. Low-pressure membranes tend to be more on the order of 93%-95% rejection.

That would mean that for residential membranes typically used for greenhouse applications, one should expect a 100 ppm input water to be purified to 1-4 ppm, but 200 ppm incoming would be 2-8 ppm.

Changing the pressure and/or temperature of the incoming water affects the throughput (L/min, gal/day), but not the purity of the water produced.

With time, there is a physical degradation of the membrane that reduces the rejection ratio - i.e., TDS climbs. Fouling of the membrane by reducing the flow of flush water reduces the throughput, but does not affect the purity of water produced.

Roberta's 150 gpd system probably has a 800 ml/min flow restrictor on the flush line, giving her about 2 gallons of flush water per gallon of water produced. Changing that to a 300 ml/min restrictor will reduce the flush water production to about 3 quarts per gallon of pure water, and will likely foul the membrane quite quickly.

Guess I didn't have to think about it much... my unit came with the various parts to make it do what I wanted it to do. (As far as the TDS of the effluent, one factor is "What goes into it?") When my membrane is new and running optimally to get 10 ppm out it's taking somewhere around 95% of the dissolved solids out. The exact value is probably not terribly accurate, cheap meter, but I can tell when there is a change - which works for my needs. Starting with better water, I'd expect the output to be better too. (However, what I do get does the job... the Pleurothallids are MUCH happier than they were with city water) It also lasts longer in winter when I don't run as much through it compared to summer when I really beat on it. because I water a lot.

The effluent has the same dissolved solids as the raw water, but the effluent TDS will be TDS(input) x (in/effluent).

With a "3 gallons raw in / 1 gallon of pure water out" system, that's 3/2 or 150% of raw water TDS.

Got my stuff today! Will try to get unboxed and either get set up or start asking a lot of silly questions, if all goes well today. Pretty excited. :D

I doubt you'll need it, but feel free to give me a call if need be. maybe I can help walk you through it.

LOL... will do, but a false alarm. Thought it was the RO stuff, but instead was grandkid's birthday gift. Some sort of transformer dragon he's been coveting. :D

Okay, half the stuff arrived. The TDS probe got lost in the Amazon world (likely eaten by a crocodile, but a replacement is on its way).

http://www.orchidboard.com/community...dium/Valve.jpg

So I think I know how the in/out thing goes together. One question... since I have five stage filtration, the pure water out tube goes after the last deionization filter, right, instead of after the membrane filter?

Then the float valve... I presume I drill a hole at the top of my fancy 55 gallon garbage can and stick the bulkhead of the float through, then fasten one of the two 90 degree elbows on the other side and screw down the bulkhead. So, which one of those two 90's do I use? The all white one is hollow. The one with the pink ring, I try to blow on it from either end and nothing happens. I'm thinking I use the all white one?

Of course, there are no instructions. I looked up a youtube by a coral reef place, and they gave instructions, but wanted me to put a check valve in line (can't remember where, but I can look it up again. If this pink thing is a check valve, it's not like one I've ever seen. I probably have some regular aquarium check valves laying around. Would that work?

Then the ball valve? What the heck is that for? I don't think I need it, since I already have a diverter on my faucet spigot with two ball valves.

I'm gonna take a picture of the end of the pink 90 elbow. Both it and the all white one can screw onto the bulkhead part of the float. The other end of each 90 are the push click things like MistKing uses.

I'll be back with another picture. Let the fun begin!

---------- Post added at 11:03 AM ---------- Previous post was at 10:46 AM ----------

Okay, pink 90. There's a little button in the middle you can push in. Doing so doesn't change ability to blow air through it.

http://www.orchidboard.com/community...0elbowpink.JPG

Aaaand, there were no blue clips for the push connects, and of course I've run out.

Either way will work, but personally, I'd put it right after the membrane. DI is really overkill for orchids - 0-1 ppm versus under 10 isn't worth the expense. The next time you need to replace that cartridge, I'd just remove it from the system.

It doesn't look to me like you have the right connection for the float valve. Yes, you put it through the upper wall of your storage tank, and the output line from your RO system connects to it, but unless the float valve stem has internal threads that will accept one of those elbows, you're going to have to buy another fitting to adapt it to the 1/4" tubing. If it fits, go with the white one.

I'm quite sure the pink one is a check valve, but you don't really need it. Ditto for the ball valve. You don't need the locking clips either, unless you or someone in your household likes to mess with your system a lot.

Check vales are usually used to prevent the pressure of a bladder tank pushing water back through the membrane, but there is no back-pressure exerted by the open air tank.

Yes, the DI filter is overkill, but I was given a couple of cartridges. I'll just disconnect and move on. Yes, one side of the white 90 degree screws into the inside of the bulkhead, so I'll use that. I mess with a portion of my MistKing tubing quite often, but probably won't with this, so I'll just leave for now and can always rob a couple off MistKing if needed. I figured the ballcock was unnecessary unless I wasn't understanding something correctly.

And that's the weirdest check valve I've ever run across. Since there's nothing involved in backflow that would go into something like an aerator and ruin it, it seemed like strange advice anyway.

I'll work at it soon, and report back with success or more questions! Gracias!

Yesterday was a real SNAFU and nothing happened. We had an ice storm, a couple of long power outages, and I just wasn't feeling it by the time power got completely restored.

Okay, a cautionary picture before I start snipping hoses.

http://www.orchidboard.com/community...m/IMG_2793.JPG

The pink clothespin is where the water goes in/out, so right now it's already cut because I removed the deionizer filter.

The green clothespin is the line that is just the leftover water that goes straight to a floor drain and runs out to some nearby flower garden and trees.

The orange clothespin is a very short piece of tube that leaves the carbon filter and goes into the big middle cannister, which is where I presume the membrane is. This is the one where I do the in/out on the top (non screws) side. Correct? So I'll just need to make a longer piece of tube there to fit it all together?

And another question...how in the heck do I know when it's time to change the sediment and carbon filters, and when I need to replace the membrane?

And I replace that whole middle tube where I presume the membrane is, or take it apart and there's something inside I change.

Ya know, I may need to make this a sticky by the time we're done. Sure would have been helpful to me, a newbie to doing RO. I used to just take a few 5 gallon jugs over to a friend's house and he'd return them filled, back in the aquarium days. Waaaay beyond that point now. We wouldn't still be friends at this pace. :biggrin:

Yes, the raw water side of the hydraulic cutoff goes where the orange clip is. The pure water side can go right where the DI filter was.

The two cartridges should probably be replaced every 2000 gallons of input water, but most folks do so every 6-12 months, depending on you usage.

The input end of the membrane housing unscrews, and you replace the membrane every 2years.

Excellent. Gracias!

---------- Post added at 01:02 PM ---------- Previous post was at 12:02 PM ----------

Drat! Drat! Dagnabbit!! Okay, I thought it was perfect. Something isn't right. Water comes out the waste side, but nothing comes out the pure water side. Here's pictures...

http://www.orchidboard.com/community...9/Help1_1_.JPG
http://www.orchidboard.com/community...m/Help1_2_.JPG
http://www.orchidboard.com/community...m/Help1_3_.JPG
http://www.orchidboard.com/community...m/Help1_5_.JPG

What the heck?

Looks to me like you have the raw- and pure water connections swapped.

Assuming it is a standard hydraulic cutoff, the blue line from the carbon filter should enter the switch on the "in" port with NO screw heads visible, and the line from the "out" port on that side should go to the membrane housing inlet.

The side WITH the screw heads should be in the pure water line from the membrane housing to the float switch.

I will look again in morning. I gave up for today. And those connections are SOOOO HARD to disconnect. Is there a secret to it? My poor stubby little fingernails. :D

For disconnecting... first make sure there is no pressure on the connection. Then, if you can't press the "ring" back far enough to get it loose... I have, on occasion, used a needle-nose pliers to present a larger surface against the ring, and pressed down on that (while pulling on the tubiing that I'm trying to remove) - just to get a little more force in the desired direction (don't squish)

Well shite, the darned video I watched said just the opposite. I should know better. Yes, it’s opposite of what it should be. I will try again tomorrow.

---------- Post added at 04:16 PM ---------- Previous post was at 04:15 PM ----------

Where in the HE Doublehockeysticks is the smack head emoji!!!

Excuse me for intervention. You have a big problem that will cost you RO membranes. Where the Flow Restrictor is connected; you must mount a valve in parallel with the Flow Restrictor (the cylinder in which the blue tube enters and the white tube comes out) to flush membranes. I mean, Ray needs to explain to you in more detail how to flush membrane.