2 RO questions:

[SlipperFan]

!. Those of you who have RO systems: How many gallons of water does your system make (per day) and how many orchids do you have?

2. Do you find your system adequate for your needs?

(Well, maybe that's 3 questions. But the first two are tied together conceptually.)

 

[Jimsox]

I don't have an RO system myself, but my father does and he uses it for his tropical fish. I was stealing for my orchids as well heehee. He just has it hooked up directly to a faucet and it goes and goes until he stops it. He actually has an alarm that senses water and he fills 55 gallon plastic garbage cans continually. I have 50 + plants and was using about 5 gallons to water and much less when mixed with fertilizer.

 

[Lanmark]

Hi Dot, my RO system is small. I don't know how many gallons a day it will actually produce since I don't have a gazillion orchids and I've never needed to filter that much water.

Background information:

My system is equipped with a 50 gpd membrane, but from what I understand RO membranes never actually produce as much water in a day's time as what they are rated for. Higher water pressure and warmer source water make for faster passage through the membrane. Lower pressure and colder temps of course do just the opposite. You must always run the RO system within the recommended pressure and temperature parameters. I have two sediment prefilters. The first one is a small cartridge containing a tiny replaceable permeable plastic element and the second is a a standard type sediment prefilter. I must replace the tiny permeable plastic element about every 6-8 weeks. Yeah, my water is that dirty. If I don't replace it frequently, my water production rate goes way down. If I didn't use it at all, I'd be replacing the more expensive standard-sized sediment prefilter much more often I do now. This standard-sized sediment prefilter as well as my other pre and post filter cartridges only need to be replaced annually, and the RO membrane itself only once every 2 or 3 years.

The more gpd an RO membrane is rated for, the less dissolved minerals it will remove from the water. The slowest membranes create the cleanest water. Still, the difference between slow and fast membranes isn't a lot and generally ranges from overall removal rates of about 95% for the faster membranes to about 99% for the slower membranes, or something like that. Fast membranes remove a lot of minerals from your water. Slow membranes remove even more.

When my tiny permeable plastic prefilter element is fresh, and I am running tepid water through my system at city water pressure rates, it takes me about 40 minutes to produce a gallon of RO water. Again, this is with a 50 gpd membrane. Not very fast, but it's enough for me. You have a lot of plants so you will want a much faster membrane than the 50 gpd membrane I have.

Have you talked to Culligan?

 

[Ross]

I have a system that's rated at 100 gpd, but due to the much colder water and lower pressure I have, it gives me more like 25 gpd. Because of heavy concentrations of iron, I have a 20micron prefilter set before a standard water softener, which then leads to my R/O system, which includes two 5 micron filters before the R/O membrane. I collect the water in a 35 gallon enclosed tank I bought from a farm supply store. I should have gotten the 65 gallon one as I have to fill buckets from the 35 gallon tank prior to watering. I use about 60 gallons twice a week to complete my watering. This does not include the water used for the daily watering of miniatures and mounted plants, Julie's watering of her other house plants, or our drinking use. I am still using the original R/O membrane installed in 2001. The rate has remained steady at 25 gpd, and the dissolved solids on the R/O water have consistently tested out at 8-10 ppm through the years.

 

[NYEric]

http://www.spectrapure.com/St_line_p3.htm
I have one of these, about $150. When the filters are fresh it makes 2-3 gph. they slow down as you use them more. they last about 6 months, then $30 +/- to replace filter cartridges. I have 500-550 orchids that I water every day using 3-4 gallons/day. When I do bi-weekly maintenance it uses about 7-8 gallons. PS, I don't have to water more because most of them are phrags that grow in water so I mostly only have to replace the evaporated water.

 

[Ray]

Dot, just remember that an RO system is not intended to be an "on demand" water system, and that - as has been stated - water pressure and temperature make a difference. (They are rated at 77°F and 65 psi. I have a table that tells you how it will be affected - Click Here

Most orchidists with moderate to large collections feed the RO output into a tank, then pump it from there. As such, if you use 25 gallons with each watering, but only water once a week, you can get away with a small unit.

If you let the system fill a bladder tank, as the tank is more and more pressurized, the fill rate drops. There are "permeate pumps" available that fake the system into thinking it's going into an empty tank to accelerate the recovery.

 

[SlipperFan]

Thanks for the responses -- all are quite helpful. But there is so much I don't understand about an RO system.

For instance, is it necessary to have the water go from the filtering mechanism into a bladder tank? Why can't it go directly into a tank, like what Ross described, even a 100 gallon tank, and from there be pumped to water one's plants? My understanding is that a bladder tank will only fill about 1/2 full, so an 80 gallon tank will really only have 40 gallons of water. And big bladder tanks are quite expensive.

Ray, I like your idea of a permeate pump.

 

[Rick]

In terms of demand I have a stuffed 8X14 GH with about 200 (maybe 300) adult plants. About 1/4 mounted. I also have a small indoor box with another dozen or so plants and/or compots.

I go through roughly 10 gallons of RO water a week for some daily misting (and spot watering) and the weekly heavy watering/feeding. Compared to some that seems to be very conservative.

My fogger and wet pads use my household well water, and probably go through 10X the RO I use much in the same week, but keeping the humidity as high as I do (70-80%) probably cuts way down on the amount of RO I use for actual plant watering.

I store my RO water in 2 1/2 gallon collapsible containers during the week, which are a convenient container for transport and storage back and forth to work.

Presently I get my RO water from work from a system that will produce ultra pure water at a little more than a 1/2 gallon per minute, and we go through about 25 gallons per day at work. So my 1.5 gallons a day equivalent for orchids is not a significant draw against it. However the size of my work system is irrelevant to what you are trying to figure out.

You can use any tank (or tote, or garbage can) as a storage tank for your RO water and don't need to pay a lot for it. However, automated fill and cut off valves are needed if you don't have time to baby sit a filling. That can take a bit more $$. At work we fill 50 liter carboys with our system, and we just use a cooking timer to tell us when (from experience) when it should be full, and manually shut off the water when the tank is full. Getting the water out of your tank to your plants is another consideration for cost vs ease of use, and will depend how far the tank is to where it needs to be used for watering and whether or not you want to use RO like from a garden hose, or put it into a pump sprayer like I do.

There have been times when we didn't hear the timer and came back to a small flood!!

 

[cnycharles]

we have huge tanks at work that hold the return water from the floor-flooding system, and they have a sort of toilet tank float system that shuts the return water off, and I'm sure you can use it for a 55 gallon system, or even a size for a big garden leaf trash can size. float gets up, turns off intake. a bladder tank will give you pressure going out of your storage system without a pump to drive your water, just as if you had a well so that your well or other pump doesn't have to run continuously, a pump in the well and the bladder tank in your basement (or anywhere). the bladder makes back pressure, so if you are pumping through your filter system into a tank that has a bladder, that back pressure will slow down how fast the water will go through your filter and into the tank. another pump after the filter (or I guess before but more likely after) that runs when your filtering is happening, will remove backpressure and let more water run through your filter system into storage. if you just pump into a tank or tub, then you would need another pump running continuously to send forth your water

 

[Ross]

I also have a float valve in my tank that shuts off the R/O water.

 

[Kavanaru]

Dot, just remember that an RO system is not intended to be an "on demand" water system, and that - as has been stated - water pressure and temperature make a difference. (They are rated at 77°F and 65 psi. I have a table that tells you how it will be affected - Click Here

Most orchidists with moderate to large collections feed the RO output into a tank, then pump it from there. As such, if you use 25 gallons with each watering, but only water once a week, you can get away with a small unit.

If you let the system fill a bladder tank, as the tank is more and more pressurized, the fill rate drops. There are "permeate pumps" available that fake the system into thinking it's going into an empty tank to accelerate the recovery.

Ray, interesting chart, but can you please explain what are exactly the values in it? ration filtered:unfiltered ; unfiltered:filtered ; something else?

 

[phrag guy]

I have a system that produces 150gpd. I have it go into 50 gallon barrels. When I water I pump the water out of the barrels to my room. In a morning of watering I use up one 50 gallon barrel. As I am watering I have the unit making water also.

 

[goldenrose]

Well Dot, are you making a decision yet?
I'm so thankful I have good rainwater!

 

[John M]

Dot, I have three 75 gallon per day membranes which produce a maximum of 140 gallons per day. My house has very hard, cold, well water. I run the raw, untreated well water to an R.O. booster pump to increase the pressure and from there the line splits off into three lines, each one going to a membrane. I used to have a prefilter ahead of each membrane; but, I stopped with that bother and expense over a year ago. The product water just empties into a 500 gallon kiddie pool in my basement. Every few months, I put a cup or two of Muriatic acid (Hydrochloric acid), into each of the prefilter housings. The acid is then fed to the membrane where it disolves mineral buildup deposits, vastly improving the membrane's productivity. Of cousre, I keep an eye on the quality of the product water to be sure that the membrane is still filtering properly and I am really getting nice, soft water for my plants. Also, the product water produced during the acid treatment is dumped and not used on my plants. To do this I simply feed the product water into a drain for about 5 or 6 hours.

To get the water to the plants, I've got a submersible pump with a separate float valve attached to automatically pump the water (via an underground 5/8" garden hose), to an underground cistern about 200 feet away, next to the green house. In the winter, I have a rubber hose that is stored inside the cistern and once a day, I pull it across the yard and hook it up to a hose end that is sticking outside through a hole in the basement door. Then, I go into the basement and manually lift the float valve until it turns on the pump. I don't have to wait for the pump to finish because the float valve will turn it off before the pool runs completely dry and damages the pump. Of course, once the water stops flowing from the basement out across the yard, through the rubber hose, it will begin to cool and eventually freeze, blocking up the hose. However, that doesn't matter because I just pull the frozen hose back to the cistern, feeding it in through a hole in the top as I pull. The water in the cistern never freezes and by the time I need the hose again the next day, any ice that formed in it while it lay on the driveway has melted.

If you'd like to see a photo of my system, here's a link to a thread over at Orchid Source Forum:
http://forum.theorchidsource.com/ubbthreads.php/ubb/showflat/Number/168653/Searchpage/1/Main/33789/Words/booster/Search/true/Re_Minimalist_RO_System.html#Post168653

 

[NYEric]

I'm so thankful I have good rainwater!

Does that mean you don't use tap water? What do you do when there's no rain or in freezing weather?

 

[goldenrose]

Does that mean you don't use tap water? What do you do when there's no rain or in freezing weather?

I store the rainwater in the winter, I have 2 barrels in the GH & then try to have 2-3 in my basement. If I'm really getting low then I'll start mixing in my well water.

 

[Ray]

Sorry for the late replay, Ramon.

The two indices are water temperature and pressure of the input to the RO system, and the intersections are the multiplier for the rated system output. As the filters do not create an appreciable restriction until they are fouled, they are not included in the calculation.

 

[SlipperFan]

I store the rainwater in the winter, I have 2 barrels in the GH & then try to have 2-3 in my basement. If I'm really getting low then I'll start mixing in my well water.

Right now, I also collect water and snow melt in my rain barrel. I have a horse tank heater in it in the winter that keeps it from freezing. I bring the water into the house in buckets to warm to room temperature for watering. But if and when I get a greenhouse, this system is very inefficient, which is why I'm looking at an RO system (I have over 500 orchids.). There is just so much I don't know or understand about RO systems. I appreciate all these responses and suggestions, and hope you will all keep them coming.

 

[NYEric]

If you have enough pressure and you dont mind the waste water [we pay for water in our taxes and apt. maintenance] there's no reason not to have an R.O. system.

 

[Ray]

I agree, Eric.

Pumping from a well, I don't have to pay for the water usage or sometimes-connected sewer charges, so i use the flush water to fill a small pond outside of the greenhouse. The dogs use it for drinking water, as do the deer in winter, along with it being a big bird bath, and several species (hybrids?) of frogs take the thing over in the summer.

Prior to putting that in, it went on the floor as a tremendous humidity source.