RO water readings

[Mark Green]

Hope some one can offer me a bit of advice.

So i purchased a new ro system http://www.osmotics.co.uk/products/6-Stage-300-Gallon-Per-Day-Reverse-Osmosis-System.html

Its been running OK since i set it up 2 weeks ago, Tds reading was around 2 so was more than happy. currently out of the tap my tds reading is around 870ppm ( very high) which is why im changing to an ro system.

However when starting the system today the reading I have is a tds 105 and ph 3.

Why the increase in tds?
Why the decrease in the ph to ph3 Last week it was 7.

Other info psi of water is only 45psi going into the system. I understaand this is low and will be looking into buying a booster pump.

Does any one have any idea what kind of booster pump I will need for this kind of system?

Thx

Mark

 

[dw1305]

Hi all,

However when starting the system today the reading I have is a tds 105 and ph 3.

Let it run for a while, water is a very efficient solvent and evn small amounts of salts will cause the TDS (really electrical conductivity) to rise.

Why the decrease in the ph to ph3 Last week it was 7.

You can probably ignore it, pH isn't really a relevant reading in RO (H2O). pH is a ratio of the H+ ion donors:H+ ion acceptors, and in pure water (H2O) you <"don't really have anything to measure">.

You can add a neutral salt (like NaCl), (but "table salt" won't work, it has added magnesium carbonate) to a water sample get a more accurate measurement.

cheers Darrel

 

[Mark Green]

Let it run for a while, water is a very efficient solvent and evn small amounts of salts will cause the TDS (really electrical conductivity) to rise.

The system had been running for 1 hour

You can probably ignore it, pH isn't really a relevant reading in RO (H2O). pH is a ratio of the H+ ion donors:H+ ion acceptors, and in pure water (H2O) you <"don't really have anything to measure">.

You can add a neutral salt (like NaCl), (but "table salt" won't work, it has added magnesium carbonate) to a water sample get a more accurate measurement.

cheers Darrel

So can I add this water straight to the tank?

I have some gh booster I got from one of the sponsor on the site, should I add this. All very confusing being new to ro usage.
Thx

Mark

 

[ian_m]

I have some gh booster I got from one of the sponsor on the site, should I add this.

Yes. Mix the required amount of boster to RO water and add to tank. If your tap water is "known" (especially if hard) then cut the RO water with tap water to add back salts.

 

[Mark Green]

Yes. Mix the required amount of boster to RO water and add to tank. If your tap water is "known" (especially if hard) then cut the RO water with tap water to add back salts.

Thx for the advice Ian.


Still unsure why My tds has increased on my last batch of ro water

 

[dw1305]

Hi all,

Still unsure why My tds has increased on my last batch of ro water

You only need a very small amount of added salts to raise conductivity, so it may just be a small amount of contaminant

The 1431 microS calibration fluid you use for conductivity meters is a 0.01 Molar KCl solution and you make that up with 0.745g of KCl, made up to 1 litre, with of DI water <"Conductivity: Theory and practice">.

If the conductivity stays high in the RO water it is a membrane issue. The harder (more salts rich) your water is, the quicker the membrane clogs.

Is there are <"flush kit"> fitted on your RO unit?

cheers Darrel

 

[Mark Green]

Hi all, You only need a very small amount of added salts to raise conductivity, so it may just be a small amount of contaminant

The 1431 microS calibration fluid you use for conductivity meters is a 0.01 Molar KCl solution and you make that up with 0.745g of KCl, made up to 1 litre, with of DI water <"Conductivity: Theory and practice">.

If the conductivity stays high in the RO water it is a membrane issue. The harder (more salts rich) your water is, the quicker the membrane clogs.

Is there are <"flush kit"> fitted on your RO unit?

cheers Darrel

Going to make some ro today so will see if the problem still exists. Will also check that the membrane has not dislodged itself.

Update. Used the system todaynand got the same readings:'( . So i checked the tds before the di stage and after. The results are before di stage 64ppm and after di stage it rises to 100. This can't be right, ive only had the system for 2 weeks.
The system has a flush kit fitted, I have been flushing 5 min before and after use.

 

[Nelson]

You could try some new DI resin.

 

[ian_m]

Does you tap water contain chloramine, as most (though not all) RO systems chloramine to chlorine which can destroy the membrane and ammonia which passes straight through and is repsonsible for high TDS readings. An ammonia test kit will show this, if this is the reason for high TDS.

If you do have ammonia, just add Prime to your RO water.

 

[dw1305]

Hi all,

So i checked the tds before the di stage and after. The results are before di stage 64ppm and after di stage it rises to 100.

Sounds like the DI resin, is the DI pod disconnected when you flush the unit?

I understand this is low and will be looking into buying a booster pump.

You need at least 60psi to get the RO membrane to work efficiently.

We have very hard water (it is from a deep limestone aquifer and good quality), and I keep soft-water fish, so I use rain-water and cut it with a bit of tap in the winter.

In the summer I use a bit of DI water to lower TDS, I only do this if the rain-water gets over about 150 microS (~100ppm TDS).

cheers Darrel

 

[Mark Green]

Does you tap water contain chloramine, as most (though not all) RO systems chloramine to chlorine which can destroy the membrane and ammonia which passes straight through and is repsonsible for high TDS readings. An ammonia test kit will show this, if this is the reason for high TDS.

If you do have ammonia, just add Prime to your RO water.

Been adding prime to the water, Still get the same results.

 

[Mark Green]

Sounds like the DI resin, is the DI pod disconnected when you flush the unit?

It would seem that the di unit is disconnected from the flush. How will this effect everything?

You need at least 60psi to get the RO membrane to work efficiently.

Currently get 45psi from the tap, I understand this is low and will need to get a booster pump. Any ideas on what kind of pump I will need for this system? Ive been quoted around £150 from the place I purchased it, not going to pay that kind of money so a cheaper option is necessary. It's really confusing what psi pump to get for 2*150gpd membrane and where to buy from

Cheers

Mark

 

[dw1305]

Hi all,

It would seem that the di unit is disconnected from the flush. How will this effect everything?

When you flush the RO membrane you get a pulse of high TDS water and that could contribute to the DI resin being exhausted.

Any ideas on what kind of pump I will need for this system? Ive been quoted around £150 from the place I purchased it, not going to pay that kind of money so a cheaper option is necessary. It's really confusing what psi pump to get for 2*150gpd membrane and where to buy from

Unfortunately I don't know, hopefully some-one else will be able to advise you.

cheers Darrel

 

[Nelson]

Currently get 45psi from the tap, I understand this is low and will need to get a booster pump. Any ideas on what kind of pump I will need for this system? Ive been quoted around £150 from the place I purchased it, not going to pay that kind of money so a cheaper option is necessary. It's really confusing what psi pump to get for 2*150gpd membrane and where to buy from

http://www.ro-man.com/shop/pumps/large-pump-for-150-gpd-systems-and-over.html ?.