Can we talk ro/di production ?

[dropabomb]

Hi guys. I’m trying to achieve the closest to 1:1 ro/di I can get. I’ve got a Aquafx barracuda 100 gpd unit that I’ve added two additional piggyback units bringin my expectation to be 300gpd. When I run my stuff I’m getting like 15glkms over the span of about 3-4 hours. I talked to Aquafx and they were great and first suggested getting a waste flow restrictor and tweaking it along with my pump to get close to 1:1 but we also talked about me living in Michigan and it’s cold as heck right now. Guessing my water going into my ro/dinis close to 40-50 degrees. Now talking to the tech he said production is cut in half with those temps. So that brings me to my next thought. Has anyone ever explored or used an Instant hot device to preheat the water to around 72 to maximize production? If so what’s been your experience? I’m searching for one that you can set the temp to your desired temp so as not to fry my membranes. Does anyone else have any other suggestions to warm or make it more manageable? My wife is not digging out water bill and I know it partly has to be the water production. Thanks for any help

 

[dropabomb]

Sorry for the typos. I have fat fingers lol

 

[Naekuh]

You decrease waste water, you burn though your RO membrane, and vice versa.

If you ultimately want to lower waste water, you probably want to run a double membrane, but chances are you will probably burn though the second membrane a lot faster then normal, and should install a flush valve on them.

I think that will be the best way to save water.

 

[dropabomb]

I think I under and but also doesn’t your brake last the longest of all the filters and I’ve read that a membrane last for up to 2 years? Also I did add another membrane, i added two more. Did you mean another DI canister?

 

[Naekuh]

I think I under and but also doesn’t your brake last the longest of all the filters and I’ve read that a membrane last for up to 2 years? Also I did add another membrane, i added two more. Did you mean another DI canister?

They last 2 years under normal usage.
I somehow do not think using RO/DI water to do water changes / filling on a large fish tank "normal usage".

And no, adding a second membrane means your plumbing another RO membrane right after the first one, so the waste water goes into the second membrane.

Here is a BRS Video on it:

However the membranes should get regularlly flushed if you do this route, to conserve the life of the membrane.

 

[rtparty]

Everything you need to know

 

[Max93]

I run 2 big sediment filters, then run a 1200gpd unit that’s used for plants (has a membrane, two carbon blocks) . Then, I connect a BRS 4 stage. My TDS reads zero for about 8-10 months. Now, I’m considering adding one more stage for silicates right after the mixed DI resin.

 

[dropabomb]

Anyone explore the heater solution? I’m considering trying a small instant hot heater that runs on 110. Set it to 72 degree water and feed my house to that and out of that to my rodi. Anyone warming water? I’ve gotta guess even in the summer the water isn’t at the testing levels of >70 degrees Thanks again guys!

 

[DCR]

Do you know how much pressure you have? I do think you need a flow restrictor to avoid wasting a lot of water. Raising the water temperature will increase production but with the right sized flow restrictor you may not need that complication,

 

[rtparty]

I run 2 big sediment filters, then run a 1200gpd unit that’s used for plants (has a membrane, two carbon blocks) . Then, I connect a BRS 4 stage. My TDS reads zero for about 8-10 months. Now, I’m considering adding one more stage for silicates right after the mixed DI resin.

You want anion resin for silicates. You would add this before the mixed bed

 

[BeanAnimal]

Anyone explore the heater solution? I’m considering trying a small instant hot heater that runs on 110. Set it to 72 degree water and feed my house to that and out of that to my rodi. Anyone warming water? I’ve gotta guess even in the summer the water isn’t at the testing levels of >70 degrees Thanks again guys!

Let's do some math.

It takes 1 BTU to raise 1 pound of water 1 degree Fahrenheit.

You have 40 degree input water and you want 72 degree output water.

Your delta T is 32 degrees Fahrenheit.

Fresh water weighs ~8.33 pounds per gallon.

32 * 8.33 = 267 BTUs of energy per gallon of water raised from 40 to 72.

You want 1:1 product to waste.

You make 50 gallons of RO/DI water.

The total water consumption is 100 gallons.

That is 26,700 BTUs of energy required.

1 Watt hour is 3.412 BTUs

26,700 BTUs / 3.412 BTU/h = 7830 Watt Hours.

So 7.8 kWh

Let's say you pay 20 cents per kWh in Detroit (I am too lazy to look it up).

You are spending $1.56 to heat that water.

But wait - some of that heat is going to leak into the room unless your heat exchanger is perfect. ASo let's call it $2.50 per 100 gallons

Meanwhile running the unit "cold" you are at 2:1

You make 50 Gallons of product and 100 gallons of waste.

That is 150 gallons

That is 50 gallons more than with the heater.

Let say you pay $6.00 combined per CCF of water and sewage.

That is about .008 cents per gallon.

50 * .008 = 40 cents.

So pay $3 bucks extra to heat 100 gallons of water
or
Pay 40 cents to waste an extra 50 gallons of water

So - no, nobody heats their water to make RO/DI

There are some expensive copper heat exchangers that can replace sink traps and your sewer stack to exchange heat with the waste water --- they don't pay for themselves usually.

 

[dropabomb]

So now that’s some math. Thank you. So I’m not near that smart but it looks like it’s cheaper to just waste the water. Is he a pump and have an adjustable flow restricted on its way. Thanks again for your time everyone

 

[BeanAnimal]

So now that’s some math. Thank you. So I’m not near that smart but it looks like it’s cheaper to just waste the water. Is he a pump and have an adjustable flow restricted on its way. Thanks again for your time everyone

It is not absolute. You see, you still "Pay" to heat the cold water in your home as it sucks energy from your home one way or the other. But YOU heat your home, so does the sun, your dog, etc. The point was that it is not worth the effort given the cost difference in water and electricity. In some other areas or conditions, it may work out differently.

 

[Gtinnel]

Also, if your method of heating the water gets the water too hot it will instantly destroy all 3 of your membranes. It’s not worth the risk or as already pointed out the cost. Depending on how quickly you go through di resin the colder water will also increase the rejection rate of your membranes and cause your di to last longer which will also save at least a little bit of money.
I also use 3 membranes in series and when it is winter my tds after my membranes is about half of what it is during the summer.

 

[Max93]

You want anion resin for silicates. You would add this before the mixed bed

I have two anions in the BRS but my ICP tests show I still get silicates, so I’m going to add a silicate specific one.

 

[LandLockedJones]

Just buy a big water container and pump the waste into that. Use it to water a garden or your lawn if you have one. That’s the best idea I’ve seen if you ask me haha.

Though I did wonder if the water would be contaminated in some way and cause issues. I doubt the grass would care, but some plants might.

 

[Gtinnel]

Just buy a big water container and pump the waste into that. Use it to water a garden or your lawn if you have one. That’s the best idea I’ve seen if you ask me haha.

Though I did wonder if the water would be contaminated in some way and cause issues. I doubt the grass would care, but some plants might.

Many years ago I would run my waste water line into my washing machine and use the water to wash clothes. If I remember correctly even the waste water is cleaner than tap water.

 

[LandLockedJones]

There ya go if you can’t reduce. Reuse.

 

[Naekuh]

Many years ago I would run my waste water line into my washing machine and use the water to wash clothes. If I remember correctly even the waste water is cleaner than tap water.

I think thats because its filtered by carbon blocks + sediment filter.
Waste water still goes though the first 2-3 stages in a RO setup.

I still think if you want to save water, running a dual RO membrane in Serial config will probably save the most, but at the cost of the second membrane wearing out quickly, and you'll probably want to flush the membranes each time you finished collecting your massive amount of water.

I would of said before that doing this is probably more expensive then the waste water, however, if you look at some locations like California for example, water is ***** expensive, and Amazon has pretty cheap RO Membranes, so you may actually save some money in the long run sacrificing the longevity of one of your RO membranes.

There ya go if you can’t reduce. Reuse.

LOL, i collected my waste water on my intial build to use to leak test my tank.
Worked out pretty well.

Then i used the water to dump it on my lawn after leak testing was done.

But rolling out a 44G Brute tub 100ft or so, even on furnature movers is a work out.

 

[rtparty]

I have two anions in the BRS but my ICP tests show I still get silicates, so I’m going to add a silicate specific one.

Do you have a cation first and mixed bed after the anions?

Silica specific resins are just marketing gimmicks. It’s anion resin with mixed bed on top

BTW some silica won’t hurt a tank. It’s actually good for a lot of critters