Reverse Osmosis Water Management

[Ray]

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

[Nexogen]

Originally Posted by Roberta

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.

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.

[WaterWitchin]

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

[Ray]

Originally Posted by Nexogen

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.

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.

[Roberta]

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.

[Ray]

Originally Posted by Roberta

(As far as the TDS of the effluent, one factor is "What goes into it?")

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.

[WaterWitchin]

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.

[Ray]

Originally Posted by WaterWitchin

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.

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.

[WaterWitchin]

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.

[WaterWitchin]

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).



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.



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

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