Pure-Flo Ro question?

[kramer51]

I know this is a dumb question but I never had a RO unit before.
I bought the ro and the float and automatic shut off kit. If the float stops the water to my resovoir tank, will the shut off valve stop the water going into the ro unit instead of it all going in the waste drain? And how much water comes out of the waste drain while the Ro is running?

Thanks in advance
I never had room before for an ro unit. I always got my water from the fish store.

 

[flapjack1439]

^^^

 

[RandalB]

The Shut-off turns off water flow to the unit, so it'll stop running water when the float closes.

Waste Depends on the Size of the RO unit (GPD) and several other factors. The unit will run a fixed amount of water to the drain at all times while operating. This is usually a ratio of waste to product 4.5:1 at optimal conditions. Now, if you have less than optimal conditions it may be more. I've seen 15:1 in some places. This is because the unit is producing less water over time.

Just made that more confusing didn't I....

RandalB

 

[flapjack1439]

I think the question is, when the ro resevoir is full and the float shuts off the output of the ro unit, will the integrated shut off turn off the water coming into the unit and stop the waste water?


Who's on first?

 

[RandalB]

Yes.

 

[rickyb]

Is that true that by running a booster pump will reduce the waste as well?

 

[maliboost]

<a href=showthread.php?s=&postid=8420205#post8420205 target=_blank>Originally posted</a> by rickyb
Is that true that by running a booster pump will reduce the waste as well?

yes, and also having the water coming in to the ro unit warmed to 78 or so degrees will help also, I added a 25 foot coil of that hose and put it in a cooler with a spare heater to heat up te incoming water, increases the output quite a bit

 

[RandalB]

<a href=showthread.php?s=&postid=8420205#post8420205 target=_blank>Originally posted</a> by rickyb
Is that true that by running a booster pump will reduce the waste as well?

Technically No. Increasing the temp or pressure will NOT decrease how much waste water the RO unit makes.

RO units produce the same amount of waste water per minute no matter what the parameters are. The difference is with higher pressure (booster pump) or temperature the unit produces more filtered (Product or permiate) water in the same period.

Here's an example:

You need 3 gallons of water. Your 75GPD membrane makes that in about 1 hour (let's say for sake of the example). During that time, the unit will waste 45000 ML or 11.888 gallons of water. This is based on a 750 ML/Minute flow restrictor that's dead on. Now, if you increase pressure with the booster pump, the unit may increase production to 6 GPH, and you'll save water by only having to run the unit for .5 hours but it's still wasting water at the same rate no matter what...

Increasing Pressure or Temperature will also increase efficiency but pressure has the most dramatic effect.


RandalB

 

[flapjack1439]

Now that's what I call a precise answer.


What's on second.

 

[kramer51]

Thanks for all of your help, I am going to try to attempt to pipe my RO resovoirs today and if enough time start to pipe my own auto top off.

Hoping I dont make a mess!!

 

[flapjack1439]

RandalB, How do you monitor a rodi system?

I assume a pressure gauge at the inlet measures the inlet pressure and when the preassure gets to a certain point the filters are restricted and need to be replaced. Measuring the tds tells you the condition of the membrane.

Am I close?

 

[RandalB]

Pretty much.

Pressure is checked at the membrane. When it drops replace the filters. A TDS meter monitors the membrane and the DI resin's effectiveness.

RandalB

 

[flapjack1439]

So, the gauge is placed between the prefilters and the membrane, rather than before the prefilters, with a drop in pressure indicating the prefilters are getting clogged.

The guy I got the unit from bought it new in June and he didn't run a ton of water through it. I've run about 10 gallons since I got it. I'm getting a tds reading of 2. Shouldn't the reading be zero?