"New" secondhand R.O. D.I. system.


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Good day guys and girls.

We have a debate and I want third party advice.
The advice from this group will make my final decision!

I acuired a secondhand R.O. D.I. system a week ago.
I'm replacing filters etc.

The debate is currently on the 3 stages infront of the R.O. membrane. Currently theres the 1 micron sediment filter, then the granulated activated carbon and then the block carbon.
With this setup I had an initial TDS of 540 and a final TDS of 20.

Some of the water in Windhoek Namibia is recycled (Yes we drink our own...... you know...... ) so its not the purest of water therefore the high TDS and we have a lot of chlorine etc. in the water. There tends to be a high amount of actual sediment in our water as well.

Another source said I should rather use a 5 micron sediment filter, then the 1 micron and then the carbon block.

Do I stay with the current configuration of, 1 micron - granulated activated carbon - block carbon or opt for the 5 micron - 1 micron - carbon block, configuration?
 

JS

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I had a very similar problem...what i did was to run a 1micron sediment....then GAC....then a filter that has micron filter ontop of a carbon block....then my ro membrane...then di resin.... 0tds
 
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dallasg

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viper357

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There tends to be a high amount of actual sediment in our water as well.
If you have high sediment then I would probably go with a 5 micron sediment filter first, then a 1 micron sediment filter and then the carbon block. Or even 2 x 5 micron sediment filters will do. My idea behind this is to trap as much of the sediment as possible in order to stop it from entering the expensive membrane. The pre-filters are much cheaper to replace than the membrane.

Maybe send @TheWaterboy a PM for advice if he doesn't come across this thread.
 
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viper357

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lol. Good luck. :p

I reckon if sediment gets through to the membrane then it will block it up and cause it to fail prematurely. That would be my line of thinking.
 
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Still undecided.

I do currently have the 5 mic, 1 mic and carbon block.
Maby I should just use what I have now instead of just buying the GAC and chucking the 5 mic.
 
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Good afternoon, guys & girls.

Below are some of the latest results for me RODI system.

July 2015
"Raw" tap water (TDS : 540ppm)
5 Micron Sediment Filter
1 Micron Sediment Filter
GAC
Solid Carbon Block
R.O. Membrane
Waste Water
D.I. Resin (TDS : 20ppm)

June 2016
"Raw" tap water (TDS : 634ppm) "A 17% increase."
5 Micron Sediment Filter
1 Micron Sediment Filter
GAC
Solid Carbon Block (TDS : 638ppm)
R.O. Membrane (TDS : 103ppm)
Waste Water (TDS : 1030ppm)
D.I. Resin (TDS : 102ppm) "A 410% increase."

I purchased all new filters today, including the resin and will replace them in due course (Likely still tonight.) where after I will monitor the phosphate situation as well as the TDS.
Let's hold thumbs that this either solves our problem or improves on the situation drastically!
 
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I certainly think if you have been using 103TDS water and you get it close to 0 you will see a noticeable difference..
 

viper357

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You could maybe consider running a dual membrane setup?
 
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Good morning, ladies and gents.

It's great to see some interest in this topic.
I just came back about an hour ago after having the TDS tested again. (I do not yes own my own meter yet.)

Herewith the latest results, below;

10 June 2016
"Raw" tap water (TDS : 631ppm) "A 0.5% decrease."
5 Micron Sediment Filter
1 Micron Sediment Filter
GAC
Solid Carbon Block (TDS : 635ppm) "A 0.5% decrease, thus cleaner drink water."
R.O. Membrane (TDS : 55ppm) "A 46% decrease in TDS, thus cleaner water."
Waste Water (TDS : 875ppm) "A 15% decrease in efficiency."
D.I. Resin (TDS : 6ppm) "A 94% improvement."

A definite improvement, though I was hoping for a near 0 TDS at the output.
The system has not "properly" flushed itself yet, so might get closer to my 0 mark in near future, but I doubt 0.

What is very mind boggling, is the fact that my drinking water, after going through the first 4 filtering stages are testing higher in TDS than the actual tap water. This is theoretically not supposed to be like this.
Neither I, nor the shop owner knows why this might be. - Pending investigation.
 

viper357

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What is very mind boggling, is the fact that my drinking water, after going through the first 4 filtering stages are testing higher in TDS than the actual tap water. This is theoretically not supposed to be like this.
My laymans understanding of it, which means I could be completely wrong :p, is that the sediment filters are there to remove just that, the larger bits of sediment in the water in order to protect the membrane from clogging up. The carbon is there to remove toxins and improve the taste of the water, these will not affect TDS of the water much, the membrane is what removes all the microscopic elements? such as chlorine, chloramine and other chemicals that make up tap water. The TDS is then the final stage which polishes off the remaining bits to bring down your TDS to 0. Perhaps running a second DI resin would further bring it down, I've never tried it so not too sure?

I think your initial TDS is so high that a normal hobby RO unit may not be sufficient enough to deal with it? I think you should send a PM to @TheWaterboy with a link to this thread asking for his input, he lives and breathes RO units from small to industrial size, he's the one to give you the best advice I reckon.
 
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