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Is 30-40 TDS good enough?

  • Thread starter mcantrell
  • Start date
mcantrell

mcantrell

I got a cheap "WaterMaker Mini" faucet mount RO filter. It's a bit slow -- 10 GPD -- but it was a good price. The water tests at about 35-39 TDS, but this is the initial batch, it's already been used (so should have already been primed) but it says to leave it on for 4 hours before using the water... So... maybe it'll get better?

But, assuming it doesn't -- is 35-40 TDS good enough?
 
It is. Lucky boy :( CA water is wayy too hard to use.
 
My tap water is that good! 20-40 TDS. I still RO it and it gets down to 5-20 TDS.
 
Frilleon said:
My tap water is that good! 20-40 TDS. I still RO it and it gets down to 5-20 TDS.
Click to expand...

You are lucky . . .

My water source ranks an ignoble 540-600 ppm. For such creepy, predatory plants, they are "panty-waists" when it comes to their water; also, RO filters here don't make it four months . . .
 
My tap water is 300-360 or so, so the RO filter taking it down to 35ish should be ok? Awesome. :) Already filled up 1 gallon, need to get some longer tubing to try and get it into a 5 gallon jug. :)
 
Atascadero, the city my ex is from, has incredibly terrible water quality. When you get the water from the tap, it's cloudy. Their dishwasher looked like a giant calcium deposit cavern. You're definitely lucky to have nice water like that.

Jason
 
At school if you put some water into a bottle, its really really cloudy, its like milk + water. Ech gross.
 
nice man, soft water is a rare thing now
ours averages around 20-25PPM
 
  • #11
I think you guys are misunderstanding me... AFTER using the RO filter, the water is 35-39. Normally it's 350-375ish.
 
  • #12
Mine is around 150. I don't worry about it. I use it for all my outdoor CPs. There's enough chlorine to smell it. The Sphagnum doesn't care.
 
  • #13
like crystal said, 150ppm will even work fine, but the key is that since her plants are outdoors, they will get top-watered by the rain. If you plan to use the tray method indoors, just make sure you top-water the pots every 2 or so weeks. I had a large pot that I filled the tray with 0-10ppm water for 6 months, and the plants started to decline. I top-watered it and tested the tds again and it read 300. So I rinsed it 100 times (almost not exaggerating:cuss:) until the tds reading lowered to 50 ppm/got sick of pouring in water and waiting :). Just goes to show you that a little ppm can go a long way.

I use 150 ppm water in a few foot-tall sundew pots in my greenshed (a tiny greenhouse my pops and i built) and I top water every time. The plants are still doing great after a year of doing this.
 
  • #14
So the standing water was 300 TDS or the water coming out of your filter was? I haven't been worrying too much about the water once it's IN the trays, should I?
 
  • #15
Would a carbon post-filter be helpful to further lower the TDS?
 
  • #16
What kind of filter did you buy? Im tired of going to the store and buying water. :(
 
  • #18
For a new system, you should be able to get it lower than that, 8 to 0. If it's already doing 30, it's okay but personally I'd like to see it be lower. My RO filter is now running at 30 and the main membrane is over 2 years old now.

The plants will be happy with 30, but just saying the system should be 8 or less out of the box once the filters have been flushed.
 
  • #19
Most TFC RO membranes are deisgned to have a rejection ratio of 95-99%. As an example, if your inlet to the membrane is 100ppm its outlet would be 1-5ppm. If your inlet was 1000ppm then the expected outlet would be 10-50ppm.

Of course this is highly dependent on water temperature and pressure differential across the membrane.

As a rule of thumb, any rejection ratio less then 90% is an indication something is wrong. Before a determination can be made that the membrane is at fault the inlet pressure, water temperature and brine rate must be measured.

It appears yours is running close to 90%. But with your filter's compact design it may use what is called a CTA membrane. These are resistant to chlorine but are a little less effective with a common rejection ratio of 83-95%.

On a "typical" system carbon block prefilters are used to remove the chlorine prior to entering the TFC membrane.

To remove what the membrane doesn't, demineralization by ionization is used with a mixed bed media (commonly referred to as "DI" )

Example system:
my_rodi_bw.jpg


my_rodi.jpg

blue = permeate
blk = prefiltered water
yellow = brine
red = fresh water inlet
white = bladder tank
clear = system inlet and outlets


HTH's
Av
 
  • #20
Sorry to hijack this post, but AV have you done any before and after comparison with that pump H? I also bought one of those, and found that it was only wasting a zillion gallons of water. At times I fill up a koi tank with my RO brine water, and when I had the pump it would fill up almost the entire 50 gallon tank. (Maybe 40 gallons?) in one draining of the bladder tank. I decided to remove the pump since I have commercial building pressure, and the koi tank will only fill up about 2 - 4", (sorry can't guess how many gallons that is) during each fillling.

Maybe it was the extra pressure that was causing all the problems though, but it's just sitting in a drawer now.

-Nate
 
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