New to Reverse Osmosis - Page 2 - Orchid Board

orchidlover69 · #11 03-17-2011, 04:17 AM

Quote:

Originally Posted by Discus

I expect (I am no expert) that it would be better to take the RO water feed off before your softener.

Thoughts from others on this? My assumption is that RO removes just about everything by 95+ %. This will hopefully be confirmed with a tds meter.

Ray · #12 03-17-2011, 11:00 AM

Theoretically, NaCl is easier to flush off of the membrane than the carbonates it replaces in the softener, so using softened water should actually give you more efficiency and life from the membrane. If the salt loading is "through the roof", some of it can still pass.

Is the white deposit salty?

orchidlover69 · #13 03-17-2011, 11:07 AM

Quote:

Originally Posted by Ray

Theoretically, NaCl is easier to flush off of the membrane than the carbonates it replaces in the softener, so using softened water should actually give you more efficiency and life from the membrane. If the salt loading is "through the roof", some of it can still pass.

Is the white deposit salty?

Short of tasting the medium, I wouldn't be able to tell you as I am not really interested in ingesting the nitrates in the fertilizer. Any suggestions? I saw the pm you sent Ray. Would you mind chatting with me on the phone? I am interested in switching out some of my collection to semi hydro, getting the ro was the first step. Pm me your number if you don't mind me giving you a ring.

DavidCampen · #14 03-17-2011, 12:21 PM

A TDS meter will help answer a lot of questions. I would suggest that you get one of those before you pay for new RO membranes.

One possibility is that you have your RO system connected incorrectly and that you are sending your purified water to the drain and using the waste water on your plants.

DavidCampen · #15 03-17-2011, 07:04 PM

Quote:

Originally Posted by orchidlover69

... As the cold water was presenting 450 grains of hardness, ...

450 grains per gallon?! That is a bit too high to believe. Where did you get that number? Perhaps you meant 450 ppm?

Explanation of Water Hardness

orchidlover69 · #16 03-17-2011, 10:25 PM

Quote:

Originally Posted by DavidCampen

450 grains per gallon?! That is a bit too high to believe. Where did you get that number? Perhaps you meant 450 ppm?

Explanation of Water Hardness

my bad

vmax3000 · #17 03-18-2011, 12:38 PM

Quote:

Originally Posted by Discus

I expect (I am no expert) that it would be better to take the RO water feed off before your softener.

I would tend to agree. I used to manage a cooling water system for a power plant that produced 11 million gallons of RO/DI water per day. If the beds or RO membranes got plugged, the fail safe was the water just flowed through untreated. So, we had to run periodic tests on water quality to ensure that all was still functioning. TDS (total dissolved solids) was one of the tests. A softener (just from what I understand, I don't have one) typically adds sodium ions to the water to counterbalance calcium ions (the "hardness" ion in water). I would speculate you could be overloading the filters, or using them up faster than expected.

If you do get a TDS meter, I would suggest testing the water pre and post RO unit to get a measure of what your unit is doing.

DavidCampen · #18 03-18-2011, 12:54 PM

No, a water softener does not "add sodium ions to counterbalance calcium ions". A water softener replaces calcium (and magnesium) ions with sodium ions.

If you have very hard water that is forming precipitates on your RO membrane then one solution is to first put the water through a softener so that calcium ions are replaced by sodium ions since the sodium salts are much more soluble.

If the OP really does have water as hard as he believes, 400+ ppm, then it would be best for him to use softened water as the feed to his RO unit.

Quote:

Originally Posted by vmax3000

I would tend to agree. I used to manage a cooling water system for a power plant that produced 11 million gallons of RO/DI water per day. If the beds or RO membranes got plugged, the fail safe was the water just flowed through untreated. So, we had to run periodic tests on water quality to ensure that all was still functioning. TDS (total dissolved solids) was one of the tests. A softener (just from what I understand, I don't have one) typically adds sodium ions to the water to counterbalance calcium ions (the "hardness" ion in water). I would speculate you could be overloading the filters, or using them up faster than expected.

If you do get a TDS meter, I would suggest testing the water pre and post RO unit to get a measure of what your unit is doing.

vmax3000 · #19 03-18-2011, 03:03 PM

David,
Thanks for the info.

Pilot · #20 03-18-2011, 05:52 PM

In regard to precipitates, I wonder if something I have attached to my RO/DI unit might help you. I have a bi-pass valve that when opened up, sweeps the membrane quickly with water and removes precip build up. My unit is fairly new (only a week old and I use it only for preparing water for my marine aquarium) but fellow hobbiests in the marine keeping forums say this "flush valve" really helps prolong the life of their membrane and filters of those who have hard water.

I'm on a well as well and I have a total dissolve solids meter that measures ppm before my DI chamber and after. My before reading shows 1-2ppm and my DI reads 0ppm. So either my well water is quite good or my system is doing an exceptional job (or both).