Ro/di

F

Foody

New member
3 months ago my nitrates and nitrites were off the charts. I had purchased my system from someone getting out of the hobby and she apparently had allowed her maintenance to lag. I embarked on an aggressive water change regiment of 40% 2 times a week for a month. I got my newest water bill today and we had used 27,000 gallons of water in the past quarter. It's possible some of that was from the previous quarter (I think the previous one was estimated).

Anyway, when I received my RO/DI system the directions said not to use the "run off" water so I ran a 25' line directly to my sump. I'm not really sure how much water gets wasted in this manner. It was suggested to me that the ratio of good to "bad" water was 1 to 5. What do others do with their "bad" water?
 
Some dirrect it to their washing machine, others collect it to water their plants. I've even heard of some using it to resurface their "backyard" ice rinks in the winter (my personal favorite).
 
I've done all of the above to reuse waste. Though, last winter was an awful season for backyard rinks. I also wanted to try topping off my pool, but never got around to running a separate line. That's probably my most consistent use for it for a quarter of the year.

Be careful running the waste line to your sump. I was filling a 30 gallon brute and ended up burning out my sump pump.
 
Now that I am back to only weekly changes, I change somewhere around 19 gallons per week (out of 55). Not sure if this makes a difference but my RO/DI originally came with a 1st stage 5 micron sediment filter and I replaced it with a 1 micron. Could possibly cause the 1/5 ratio to be skewed.
 
I wouldn't have guessed that going with the 1 micron prefilter would impact your product/waste ratio.

How old is your membrane? Do you flush it? What's your pressure when it's running? I'm leaning more toward a bad flow restrictor.
 
I haven't flushed the membrane. I've only had the entire rig for about 4 months. How does one flush the membrane, anyway?
 
Some RO/DI units are sold with a flush kit built in. If yours doesn't have it, don't worry about that for now.

Any rough idea how many gallons you have put through it? Do you know your input water pressure and temperature? Can you list exactly what is in each stage of the unit and if that was the way it came or if you have swapped it for something else?

Have you measured your actual product:waste ratio?

How long is the line for the product water?
 
Any rough idea how many gallons you have put through it? probably about 400 gallons of usable water

Do you know your input water pressure and temperature? No idea. Standard Monroe County Water pressure

Can you list exactly what is in each stage of the unit and if that was the way it came or if you have swapped it for something else? I put it together with the tech support on the line. sediment followed by a different paper filter (looks like a corrugated paper filter) followed by a carbon filter followed by another carbon filter followed by the membrane.

Have you measured your actual product:waste ratio? No

How long is the line for the product water? about 2 feet
 
Ok, I just ran both lines into a bucket and turned the filter on. After 12 minutes I had 1/2 gallon of usable water and 1 1/2 gallons of discharge, so a 1 to 3 ratio. I'm actually quite pleased with that.
 
A ratio that is TOO good may point to issues though. Do you know what your TDS value is at input, membrane product, and DI product? What brand and model of membrane do you have?

It would be interesting to pull the 25' waste line off, put on a 1' hose, and measure the ratio again. If the excessively long waste line is acting like additional restriction on the waste side of the membrane, it could be throwing things off.
 
Don't have a TDS meter and I don't know the brands. I would have to pull the membrane out to determine that.
 
Owning an RO unit without a TDS meter is like owning a computer without a monitor. You need a TDS meter to run an RO.
 
Explain please. I understand that the first minute or so of water is much higher in solids. After that, what would the purpose of the TDS meter be?
 
To make sure your RO is actually functioning and to know when to replace the filters. Without a TDS meter you have no idea if your unit is even taking anything out of the water.
 
IMO, even a cheap TDS meter is effective, in terms of understanding whether or not your unit is performing and whether or not your filters are ready for replacement. You could get one for between $10-20.
 
Ok. TDS meter on the way. The longer I stay in the hobby the more expensive it gets. Do folks calibrate their TDS meter similarly to their refractometer? How exactly do you use the meter, as in when, how often and at what stages in the process of drawing water?
 
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