[cybersye]

I have a merlin with an additional 10 " pre sediment filter, my tds in is between 350 -400. Product after ro is about 30. I know others on here get a much lower tds and some about the same even higher. I tried an ro man 450 gpd before that and it was even higher. My pressure is 80 psi.
I think it was jm123 who replied to my posts a long time back when I first set it up explaining that the chemical make up of water can vary significantly thus performance from an ro will vary too.

My question is .
Can I find out exactly what is in my water that gives me such high readings after ro, compared to people in other areas. Is there a supplier who could test a sample of it ?
If so then maybe there would be a better filter I could put on it before ro to improve the merlins performance
e.g. maybe the water has higher than average chlorine etc.?
Its just an idea
Your thoughts welcome
Thanks
Simon

[MJH]

i have a similar high tds from tap, i started with a 200gpd RO and the TDS wasn't great after RO around 60, so i got a 4040 RO and to be honest its very good after RO my TDS is down to 10 and 0 after DI.
I know this doesnt answer your question but if and when you can afford it, its well worth an upgrade if you live in hardish water area.
Matt

[JM123]

Hi Cyberseye.

Chlorine is not a dissolved solid (as chlorine isn't a solid).

Send me 2 water samples, one of tap water and one of water from the merlin that hasn't been di'd.  Make sure you let the merlin run for 10mins before taking a sample.  I can have the water tested at a local facility for you.

One thing I have noticed in high tds regions is that it is mostly calcium carbonate which causes the probs (lime).  Chances  are your inlet water is very high in calcium carbonate.  Does your kettle scale up? If so then a water softener is the answer.  It will soak up the lime in the water leaving the merlin free to tackle all the other minerals.

But send me those 2 water samples anyway.  Email me j.mills175@btinternet.com for the address.

[*foxman]

Cybersye,

Merlins only do about 90% filtration so you've good a very good result as it is. the next step up is industrial RO territory but you will pay at least 3 times what you bought Merlin for.

[JM123]

foxman, GE claim rejection between 95 and 98%. 

every membrane performs differently with different minerals/contaminants etc.  However, you should be looking at output  less than 15ppm, not 30ppm.

[cybersye]

thanks for all your replies, I've a small flat with a 250ltr weeliebin in a cupboard with a 250 ltr tank in a small van so the merlins been ideal for me as for the speed that i can produce ro water. So although a 4040 ro would sound the way to go I'm not in a position to invest that much or have the work capacity to warrant it. People have had similar high mains readings and get better results in some cases.
Thanks jm123, I was unaware as to wether chlorine would make a difference to tds but used it just as an example not knowing too much about the make up of water. I may well send some samples off to you in that case. From the little research I have done a water softner unit can be a bit pricey too and need to be recharged often? so I would save some on resin and pay some on a softner, would it be worth it?
I do know someone who works in a lab for southern water so it maybe I can get them to test a sample but thanks for your input jm123, I shall be in contact by e mail if I need to.
Simon

[Kinver_Clean]

We had problems with this in the early stages. Our inlet is about 180 with low calcium carbonate but higher magnesiums. We replaced the ro membrane and got an automatic electronic flush control that flushes regularly during the tank fill. Since then our after RO reading has been 4 and after DI 0. This has been maintained for sveral months with one fill of resin. At this rate our 5 lt of resin will last years.

Trevor

[JM123]

Hi cyber, if you can get your friend to test the makeup of the water for you then thats the best thing to do.

Once you get the results get back to me.

[*foxman]

foxman, GE claim rejection between 95 and 98%. 

No, i think you will find it's 90% have a look at the performance data. It will produce water at a better rate with the right conditions but those conditions are few and far between. Too produce what you have claimed is completely unrealistic for a system working off mains pressure.

[JM123]

http://www.ge-merlin.com/#info

90% minimum, 99% maximum.

http://www.ge-merlin.co.uk/MerlinPerfData.pdf

look at specific contaminant performance on page 2.

[KarlJones]

he is getting between 91.5% and 92.5% reduction.
The website does say the average result was 93% @ 750 GPD, so he isn't miles away.

H is going to get over 16,500 Liters from a sack of DI Resin, so that itself is costing him half a penny per liter.   If he uses 200 Liters a day, 5 days a week, he would still only need to refil a 7Ltr resin bottle every month.   If he uses 100 liters a day for 4 days a week,  then it would last him two months between refils.

My point is, that although 30 is higher than most of us would like, at 92% reduction it is working and it is doing what you want...  cutting the costs.    We can easily slip into the mistake of thinking the RO is for bringing our TDS down.  It isn't!  Thats a shock eh?  The RO (or merlin) is so we can produce pure water in a cheaper way. 

[Davew]

My tap water is 350ppm, after my 300gpd Roman I get tds of 5ppm and I live in a hard water area with water pressure of only 35. I boost it to 65 but often leave the ro running overnight without the pump. This is without di too.

[KarlJones]

Thats what I am talking about, in order for him to achieve 5 tds he is going to have to dip his hand in his pocket and try lots of things out.  Eventually it might work out, but even if it does the amount he is saving per year is minimal in the big scale of things.  So he might end up spending an extra £20 a month or so on resin compared to someone with 5 TDS,  but is it really worth all that investment and head ache just to save a quid or so per working day?
 

[Davew]

Just that my tap water tds is high yet my pressure is low but my water produced is quite close to pure. like someone said is there a chemical in the tap water that would prevent your ro working well?

[*foxman]

http://www.ge-merlin.com/#info

90% minimum, 99% maximum.

http://www.ge-merlin.co.uk/MerlinPerfData.pdf

look at specific contaminant performance on page 2.

JM123 that is a fake Merlin site, it says at the top of the page, the data is not trustworthy. This is the real one:-

http://www.ge-merlin.co.uk/MerlinPerfData.pdf

have a look at the first table TDS average reduction, that is the figure to go on
89.7

[JM123]

foxman - that is the page I have quoted.

also the influent nitrates is very high, very high actually - I think the recommended max mg/ltr in the UK is somewhere round the 20mg/ltr mark.  So if you take that into consideration that will ultimately increase the efficiency of the merlin.

I'm not trying to argue a point, its clear to see that everyones water makeup is very different in various parts of the country.

[*foxman]

JM123, the only figure that matters to window cleaners is the TDS - which comes out at 90% which is pretty acurate.

In that table they have only named a few contaminents there are others not mentioned, this is covered by the TDS average of 89.7%. Some people do get very good results with a Merlin but the correct average is 90% if you go on this no-one should be dissapointed expecting more than it's capable of.