Two RO/DI Questions

[Macimage]

What is the reason for running your waste water 4/1 and not 1/1 or 2/1? I have an adjustable restrictor and I don't understand why I need to open it up to waste so much water. Does it use too much DI resin or ??? to go produce 0 tds?

Also, after 5 years my 3 gallon holding tank is adding tds to my output water. When I bypass it, I have 0 tds and when I turn fill it up and then test it, my tds was 35 for the first tank I filled and threw out and 17 for the second. Right now I have it bypassed until I find out how to clean it out correctly.

Thanks!
Joyce

[AZDesertRat]

What we refer to as "waste" is actually the brine or flush water. This is what carries the solids away from the membranes surface so it does not plug. The 4:1 is what the industry has come up with as a happy medium, any less and you shorten the membrane life significantly, any more and you start to see reduced production due to lack of pressure to drive water through the membrane. If you have near pristine tap water you may get by with 3:1 but I would not go any lower than that. Manual flush valves do not take the place of having the proper waste ratio.

If you are talking about a 3 gallon bladder or pressure tank, you can disinfect the tank using a very very weak hydrogen peroxide or bleach solution but it might be better to buy a new one.

There is a system available today that has a true 1:1 waste ratio, it is the MaxCap UHE from Spectrapure. This system uses a microprocessor along with a booster pump and solenoids and pressure regulators to perform automatic flushes with DI water. It has been in testing for a couple of years and finally made available just recently. I purchased one myself last week and am in the process of hooking it up this week. I'll keep everyone posted on how it works!

[wife no likey]

chances are that your TDS is increased when using the bladder tank due to "TDS creep"

This is caused by your RO being short cycled to keep the tank full.

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I don't think it's tds creep this time, as I was testing it several times that day before it was full because I was working on it. But that's a good point to remember, as I'd never heard of it.

I'd like to try to clean the tanks, as I have two and they were not cheap.

How do I get the bleach into and out of it?

Thanks!
Joyce

[axeo]

DesertRat,

Is SpectraPure, in general, the way to go? TIA.

[AZDesertRat]

I would say if you have abnormal water conditions or want superior water quality, yes. If you have very low TDS to begin with the payback period would be longer but above 250 TDS or so the price difference is more than made up in savings on replacements over a year or two. The hand tested and guaranteed 98+% rejection rate membranes and 100% custom hand blended DI resins are unique to them and only them as far as I know.

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How would I clean out these 3 gallon holding tanks? Do I use a syringe to get the bleach in or ??? How much should I use??? Then would I just run my RO through it a few times? If any bleach is left, would it show up on my tds meter?

Thanks!
Joyce

[AZDesertRat]

Disconnect the tank and let the air pressure out of the schrader valve. Mix a spoonfull or two of regular bleach or better yet hydrogen peroxide in a gallon of water and pour it in the top of the pressure tank. Swish it around and let it sit an hour or so. Pour it out and rinse several times with DI water. Add 6 psi of air back to the schrader valve and reconnect the tank.

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AZ-Thanks so very much! Is the schrader valve the one on the top?

I never even thought of taking that valve off the top. I was thinking along the lines of trying to run the bleach through the entire RO system somehow.

There is a small knob to turn at the bottom of the tank that the directions said not to adjust. Do I do something with this one or just the one at the top that I feed the water into and out of??

How do I know how much psi of air I've added back and how would I do that? Scuba tank or hubby's air compressor for flat tires?

Joyce

[AZDesertRat]

What appears to be a knob is just a plastic cap. Take it off, bleed the air out of the valve behind it (its juts like a bicycle or car tire schrader valve). Disconnect the 1/4" water line from the valve on top of the tank, it may be easiest to unscrew that plastic elbow or valve, and pour the solution into the top of the pressure tank. You may need a funnel.
Once done, rinse it out and add 6 psi of air back to the tank, use a bicycle pump and gauge and its real easy.

[Macimage]

Thank you for the explanation and detailed instructions. As you could see, I really had no clue how to dismantle, clean and reassemble these tanks, but they do need it.

Thanks again AZ!
Joyce