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Merlin RO more efficient in winter??


ShropsWindowCleaner

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ShropsWindowCleaner

Hello all. I use the old Merlin RO but with carbon filter and membranes fitted in July, so fairly new. At its peak during summer/autumn i was getting a 97% rejection rate at 85psi on a booster pump. 421 ppm from mains down to 13ppm before DI. I tested it yesterday and now i’m getting a 98% rejection rate. 421 ppm down to 9ppm at the same psi. Are RO’s more efficient in winter? Or just improved with use? I’m relatively new to purifying my own water. I only started purifying my own in July having purchased pure water for a long time. Just wondered what the science was behind it? Thanks in advance 👏🏻

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Interesting. You normally lose efficiency in winter as the cooler the water the harder it is to push through the membrane as it's viscosity increases the colder it gets ! I think manufacturers quote Gallon Per Day values based on water at 20 Deg C and for each 1 Deg C they say you lose 1% of efficiency, which seems a huge loss to me. 

When you say do they get better with use, when did you first measure? I assume you test on a regular basis as other wise you won't know if something is wrong till you get custys complaining about spotting?

  

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ShropsWindowCleaner
16 minutes ago, ched999uk said:

Interesting. You normally lose efficiency in winter as the cooler the water the harder it is to push through the membrane as it's viscosity increases the colder it gets ! I think manufacturers quote Gallon Per Day values based on water at 20 Deg C and for each 1 Deg C they say you lose 1% of efficiency, which seems a huge loss to me. 

When you say do they get better with use, when did you first measure? I assume you test on a regular basis as other wise you won't know if something is wrong till you get custys complaining about spotting?

  

Last tested it 8 weeks ago 🤦🏼‍♂️ Was getting 97%. Weird how it’s got better at 98%. Still, i’m not complaining 😂 Need to change my DI resin soon though, only getting down to 2ppm. 

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It may be your water TDS that has changed. My TDS water from the tap for along time was between 270-285. They have carried out some work in this area and now my TDS is 84-90. Massive drop, my resin is lasting much longer. 😃

A lot of people still use pure at 2. It depends on how you feel yourself. Some change at 1 some 5 some even higher. It’s a personal preference really. But always check for spotting etc. 

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ShropsWindowCleaner
1 hour ago, Martyn said:

How quickly did you test it after setting it running? They take a few minutes to reach peak efficiency.

Ran it for an hour then tested 👍🏻 But yeh i agree, need running for a while first 👍🏻 I’m using Unger resin at the mo. Been great so far. 

This comment is now going ‘off thread’ but is there a difference between Unger and Tulson resin? Or is it personal preference? Apologies for taking the discussion in another direction 🤦🏼‍♂️

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It's always been said that Tulsion MB115 is the best but as I understand it the chemical make up of the water has a part to play in which resin works best.

 

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On 06/01/2021 at 14:27, ched999uk said:

Interesting. You normally lose efficiency in winter as the cooler the water the harder it is to push through the membrane as it's viscosity increases the colder it gets ! I think manufacturers quote Gallon Per Day values based on water at 20 Deg C and for each 1 Deg C they say you lose 1% of efficiency, which seems a huge loss to me. 

When you say do they get better with use, when did you first measure? I assume you test on a regular basis as other wise you won't know if something is wrong till you get custys complaining about spotting?

  

... and added to this they also ensure the water pressure and the mixture of dissolved solids in the water they are testing are exactly right to ensure best performance.

To get the best shot a photographer has the choose not only the right scene but also has to get the lighting right as well.

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