RO unit producing 40 ppm

[ThomasG07]

My brand new aquaticlife 3 stage RO unit is producing 40 ppm water. Any suggestions on why this might be?

Sent from my SCH-I545 using Aquarium Advice mobile app

 

[BigRedsReefs10]

Is that a ro/di unit or just ro? And do you mean tds? If just ro that's normal

 

[Tobykourtney]

Check you tds coming out of the tap. When I just run the ro on my aquaticlife it comes out 30. It all depends on how much your tds is to begin with. Mines 500-600

Sent from my SAMSUNG-SM-N900A using Aquarium Advice mobile app

 

[ThomasG07]

It's 400

Sent from my SCH-I545 using Aquarium Advice mobile app

 

[Tobykourtney]

Do you have the 100 gallon per day or 50 gallons per day?

Sent from my SAMSUNG-SM-N900A using Aquarium Advice mobile app

 

[ThomasG07]

Do you have the 100 gallon per day or 50 gallons per day?

Sent from my SAMSUNG-SM-N900A using Aquarium Advice mobile app

100gpd

Sent from my SCH-I545 using Aquarium Advice mobile app

 

[Tobykourtney]

I've heard the 100 gpd filters are less efficient. I don't know which ro membrane they use but most of the commercial filters I've looked up are 98% efficency for all but the 100 gpd which is 90% which sounds right for what your showing.

Sent from my SAMSUNG-SM-N900A using Aquarium Advice mobile app

 

[ThomasG07]

I guess I will have to make do with 40ppm. And eventually get the DI unit as well

Sent from my SCH-I545 using Aquarium Advice mobile app

 

[Tobykourtney]

I just checked mine and I've got 582 out of tap, 34 out of ro and 0 out of di. I would strongly recommend the di if your doing saltwater I tried just ro and got cyano bad.

Sent from my SAMSUNG-SM-N900A using Aquarium Advice mobile app

 

[Linwood]

90% rejection rate is a bit low, if the filter is new I would expect better.

Are you letting it run a bit, and are you flushing the membrane?

I have about 370 ppm input water, a common Dow filter, and am getting about 20 ppm out of the RO side, but for the first pint or so it is more like 35ppm (decreasing), even if I have flushed.

What I do is:

- Open the RO tap (blocking DI)
- Flush the filter about 3 minutes (i.e. no flow restriction)
- Add flow restriction so it is making RO water, let that run for another 5 minutes
- At this point I'm getting about 20 ppm
- Switch it to go through the Di filter
- Let that flush for another 5 minutes or so (even though it is always 0 ppm so far)

Collect water.

When done, close off the DI, flush the membrane again for 3-5 minutes, and put it all away.

When the membrane is not under pressure there can be flow of dissolved solids across the membrane which means initial water out is higher.

On the other hand, if you are steadily getting 40ppm, it may just be the type of minerals -- any given membrane has widely varying rejection rates for different contaminants. I wouldn't worry unless this rises.