Reverse osmosis system

[Deleted member 7446]

A very good evening all, I hope you are all well.

So here is my 1st ever R/O system question ever asked. 

As I am someone who is fortunate to live in an ultra soft water area, I have seen this system listed locally for sale and the price is peanuts in comparison to a new system available today. 

With the increased demand on Resin and the fact I use DI vessels only to produce my pure water i thought adding a compact sized Reverse osmosis system into my production would keep my resin consumption down and still give me good quality pure water at less of the cost. 

The system is complete in respect of its component / housings and fittings

I happily acknowledge the fact that buying 2 new membranes and a pre filter isn't an issue and possibly consumables such as new O rings aswell. 

The system looks to be a GE Merlin 720 gpd 

Everything is there and using it along with one of my Unger hydropower DI's as a polisher would save me some money in the long run.

What membranes and pre-filter would be recommend along with a marginal cost ?

Many thanks 

Austin 

 

[brianbadonde]

How soft is your tap water? If it is a really low TDS I would think the extra water usage ie the waste you would creat,  would increase your bills more than the cost of the replacement membranes and filters. Not sure what the recommended cut-off point for getting an RO is exactly but I would have thought 80PPM or somewhere around that mark? I’m happy to be corrected though......

 

[Part Timer]

I appreciate you're a talented DIY nut but in this situation asking before buying would benefit.

How much pure do you use weekly, what is your TDS and pressure. When we know this then @spruce, @doug atkinson, and others will be able to help more than me

 

[Deleted member 7446]

How soft is your tap water? If it is a really low TDS I would think the extra water usage ie the waste you would creat,  would increase your bills more than the cost of the replacement membranes and filters. Not sure what the recommended cut-off point for getting an RO is exactly but I would have thought 80PPM or somewhere around that mark? I’m happy to be corrected though......

evening Brian. It's between 54 & 72 ppm 

 

[Deleted member 7446]

I appreciate you're a talented DIY nut but in this situation asking before buying would benefit.

How much pure do you use weekly, what is your TDS and pressure. When we know this then @spruce, @doug atkinson, and others will be able to help more than me

tds on average is 54-72 ppm home water mains pressure is 64.3psi 

Unfortunately I'm having to move soon and not sure where home will be. So hence the inquiry as my may be leaving soft water land 

 

[Part Timer]

tds on average is 54-72 ppm home water mains pressure is 64.3psi 

Unfortunately I'm having to move soon and not sure where home will be. So hence the inquiry as my may be leaving soft water land 

Unfortunately without basic info we're as ill informed as you are. Hard water, low pressure and water meters are potential nightmare scenarios.350gpd might be ok for single operations 

 

[ShropsWindowCleaner]

I use that Merlin system in my van. My tap water is 410ppm on average and the Merlin brings it down to 11ppm. I do use a booster pump into the Merlin tho at 85psi. 

A very good evening all, I hope you are all well.

So here is my 1st ever R/O system question ever asked. 

As I am someone who is fortunate to live in an ultra soft water area, I have seen this system listed locally for sale and the price is peanuts in comparison to a new system available today. 

With the increased demand on Resin and the fact I use DI vessels only to produce my pure water i thought adding a compact sized Reverse osmosis system into my production would keep my resin consumption down and still give me good quality pure water at less of the cost. 

The system is complete in respect of its component / housings and fittings

I happily acknowledge the fact that buying 2 new membranes and a pre filter isn't an issue and possibly consumables such as new O rings aswell. 

The system looks to be a GE Merlin 720 gpd 

Everything is there and using it along with one of my Unger hydropower DI's as a polisher would save me some money in the long run.

What membranes and pre-filter would be recommend along with a marginal cost ?

Many thanks 

Austin 

View attachment 21916

 

[Deleted member 7446]

With the upmost respect and without offending anyone I was only asking what are the membranes and prefilter that this unit would of came with from new. It was being sold as a caucus.

Not to worry it sold. It was only £15 

 

[doug atkinson]

Pentair bought out the company and immediately the price of membranes increased. A set of membranes and filters would have set you back around £266.00. There are copy membranes you will find on Ebay a lot cheaper but inferior quality.

The rejection rates of these membranes are not good at 96% and waste is high.

To save on cost on resin it would be more efficient going for a 4021 HF5 system.

 

[Deleted member 7446]

Pentair bought out the company and immediately the price of membranes increased. A set of membranes and filters would have set you back around £266.00. There are copy membranes you will find on Ebay a lot cheaper but inferior quality.

The rejection rates of these membranes are not good at 96% and waste is high.

To save on cost on resin it would be more efficient going for a 4021 HF5 system.

A very good afternoon Doug and many thanks for your reply.

I will be moving soon but not sure where. I may end up buying a complete new system at some point and save money on resin to a degree.

I really appreciate your valued knowledge and skill within the industry 

Kind regards Austin 

 

[spruce]

If you are on a water metre then these r/o's are best avoided. From new a local lad could only get a 90% rejection rate with a 5 to 1 waste to pure ratio.

You could fit an inline gate valve onto the waste to throttle it back. At your low tds you could well run at 55 to 45 waste to pure ratio.

I would also add a small sediment prefilter to save the carbon block inside the Merlin.

 

[Deleted member 7446]

If you are on a water metre then these r/o's are best avoided. From new a local lad could only get a 90% rejection rate with a 5 to 1 waste to pure ratio.

You could fit an inline gate valve onto the waste to throttle it back. At your low tds you could well run at 55 to 45 waste to pure ratio.

I would also add a small sediment prefilter to save the carbon block inside the Merlin.

Thank you. 

I already use a carbon block and 2 sediment filters 5 to 2 microns 

Keeps the crud away from the resin