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Recommendations for booster pump please.

brianbadonde

Well-known member
Messages
419
Location
Andover
Hi folks. I hope you are all managing ok during this cold snap!
 

As the title suggests, I believe I need a booster pump. I’ll give as much info as I can to paint as accurate a picture as possible.

I have had a 2400GPD 40-20 RO system for about 9 months now. My water pressure is on the low side so I opted for an HF5 low pressure membrane.

Initially, the TDS was 15PPM from the membranes from 343PPM, 95% efficiency which I was ok with (I know it should probably be lower but I could live with that). However, it is now 30PPM, so only 91% efficient, and that is with regular flushing ie 15 mins twice per week and also a minute or two before using.
 

Membranes have been changed regularly. I have changed them every 3 months. The waste to pure ratio is about 3:2, or 60%-40%.

It is probably relevant to know I use on average about 400 litres of pure per day, 5 days per week.

Pressure measured from the garden tap is just under 50PSI. Pressure in the gauge between prefilters and membranes reads about 40PSI.

My understanding now is that ideally I need a pressure of between 80-100 PSI for optimal performance.

I don’t know much about booster pumps. Is it a case of they just turn on and off, ie work at full pelt or not at all? I just feel a bit confused as to how they work. I am thinking I need one that the pressure can be adjusted to suit the membranes optimal performance? 
 

Apologies if I sound silly with these questions, but just feel a little bit confused by it all. It has been a case for me up to now that I just switch it all on, produce pure, and go and work. Now my work load has increased over time I have realised there is a lot more room for me to produce water more efficiently. Seems I am always replacing resin!

Thanks in advance folks ?

 

spruce

The Sprucefather
Messages
8,003
Location
Teesside
Hi folks. I hope you are all managing ok during this cold snap!
 

As the title suggests, I believe I need a booster pump. I’ll give as much info as I can to paint as accurate a picture as possible.

I have had a 2400GPD 40-20 RO system for about 9 months now. My water pressure is on the low side so I opted for an HF5 low pressure membrane.

Initially, the TDS was 15PPM from the membranes from 343PPM, 95% efficiency which I was ok with (I know it should probably be lower but I could live with that). However, it is now 30PPM, so only 91% efficient, and that is with regular flushing ie 15 mins twice per week and also a minute or two before using.
 

Membranes have been changed regularly. I have changed them every 3 months. The waste to pure ratio is about 3:2, or 60%-40%.

It is probably relevant to know I use on average about 400 litres of pure per day, 5 days per week.

Pressure measured from the garden tap is just under 50PSI. Pressure in the gauge between prefilters and membranes reads about 40PSI.

My understanding now is that ideally I need a pressure of between 80-100 PSI for optimal performance.

I don’t know much about booster pumps. Is it a case of they just turn on and off, ie work at full pelt or not at all? I just feel a bit confused as to how they work. I am thinking I need one that the pressure can be adjusted to suit the membranes optimal performance? 
 

Apologies if I sound silly with these questions, but just feel a little bit confused by it all. It has been a case for me up to now that I just switch it all on, produce pure, and go and work. Now my work load has increased over time I have realised there is a lot more room for me to produce water more efficiently. Seems I am always replacing resin!

Thanks in advance folks ?
I presume you mean prefilters rather than membranes.

I don't know the answer to the problem you have. But once you start dealing with low TDS counts like 30ppm it is now down to the composition of those dissolved solids in your current water supply that would determine that membrane's efficiency. If those particles are very small then they would probably just pass through the membrane 'pores' the same, even with boosted pressure. The higher the tds of your tap water the more chance your membrane would remove a higher percentage of dissolved solids.

Your membrane will never remove all the dissolved solids from the water, no matter how efficient it is. So if it's removing 28ppm of 30ppm of tap water I wouldn't see a problem. Economies of scale will tell you that even if you managed to get a pure output reduction of 1ppm the cost of adding a booster pump is never going to justify the cost saving of resin to polish it off.

I might try to restrict the waste output a tad to say 55 waste to 45 pure and see if that makes a difference. If it does it won't be much. Remember your tds gauge just isn't that accurate either - it's just a guide.

When you start dealing with small increases or decreases, percentage figures start to get very distorted. For example, if the Covid infection in our village was 1 last week and 2 this week, that's a 100% increase; but it's only one additional case. The 100% increase is alarming whereas 2 in a village of 50,000 paints a different picture.

 
Last edited by a moderator:
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