RO DI first time user

[heranatomy]

I have recently purchased a RO DI unit (SpectraPure ProPlus)

I haven't used it yet, but I had some questions before I kill my water bill, lol.

These are total noob questions, and I apologize ahead of time.

First question: When I first start my system, I know I have to flush water through it initially. I was wondering if I could stop the flow and restart it again. For example, I think I'm going to use the cold water from my washing machine hoses. I would need a bucket to flush the system. I would like to turn off the water, while I take the bucket and dump the "flush" water. Then, I would like to set the clean output and waste output lines in separate containers and restart the flow. Is it okay to start and stop it? Or would that make me have to flush again?

Second question: Say my RO DI unit is rated for 90gpd. Is this of usable water or a combination of waste and usable water?
Also, what happens to the actual unit if I produce MORE than that? Does it automatically shut off or is the output just all bad?

Third question: Say I want to produce only 30 gallons of good water...is it okay to shut the flow on the unit and NOT use it to it's full potential?
Does anything I've already mentioned harmful to the unit?

Thanks guys.

 

[AZDesertRat]

A RO/DI won't add much to your water bill, you probably won't even notice the difference in fact. Say you make 100 gallons of treated RO/DI in a month, that means you will have 400 gallons of waste or 500 total gallons usage. My water is like $2.50 per thousand gallons at its highest rate so I used $1.25 for the month. $1.25 for 100 gallons of RO/DI is cheap compared to buying it for 0.25 to 0.75 per gallon at the LFS.

Yes you can start and stop it during its break in period, or any time in fact. The only thing to keep in mind is the longer the filter runs the better it is for the RO membrane, constant starting and stopping like in a drinking water system is not efficient can leads to TDS problems.
You will want a pretty big bucket for the waste stream as it can produce as much as 15 gallons of waste per hour and 3.75 gallons of treated water.

If possible I would set it up next to the kitchen or bathroom sink or a laundy sink if you have one so you have a place to flush the water to. Another option is stick the waste in the washing machine but they have a limited capacity too.

The 90 GPD is treated RO/DI water. Thats 90 GPD at 60 psi incoming pressure and 77 degrees F water temperature, your conditions will vary so expect 2/3 to 3/4 that amount in most cases, especially in winter months with colder water. If your pressure is over 60 psi and/or your water temperature is higher than 77 (DO NOT try to blend hot and cold water to obtain a warmer water) then you will see more than 90 GPD which is fine, I actually get about 100 to 110 in summer months in Phoenix. The quality is still the same but you get more or less water.

Sure, you can make as much or little as you need. Keep in mind it is better to make say 5 gallons or more at a time so the membrane gets well flushed but you can do more or less according to your needs. What happens is when a membrane first starts it produces a spurt of higher TDS water called TDS creep. Actually it relates to when the unit is off and not producing water. When sitting static contaminants equalize on both sides of the membrane so when you start it back up it has to purge those accumulated TDS which is the TDS creep you see for a few minutes before it drops to normal levels. This exhausts your DI resin quicker so making less frequent, larger batches is preffered.