# RO FILTER



## VanEternal (1 Nov 2020)

Hi,
This might be a stupid question, I have not used reverse osmosis filters before . When doing water changes using the RO filter and considering the fact that most affordable filters produce around 190l /day which means it will take around 12 hours to do a 50% water change. Therefore my question is whether theres an automatic shut off option, to prevent it from overflowing the tank. Or does it have to be turned off manually ?


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## Mr.Shenanagins (2 Nov 2020)

There are what’s called “float” switches. Once the water reaches a desired level it cuts off the flow. I can’t comment on how safe they are though.


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## papa_c (2 Nov 2020)

My suggestion is to use a collection barrel and not feed the water directly to the tank, I use a cheap mini float valve from aliexpress, used it for the last 2 years with no issue.

With an RO unit, the RO membrain housing has 2 outlets 1 for waste and 1 for clean water. 
You must make sure the filter also has an auto shut off valve, when the collection tank is full and the float valve closes pressure builds in the clean water line which forces the auto shut off valve to close cutting the supply water, without this water will simply flow out the waste line.

I have a 75 GPD filter with a 70psi electric booster pump fitted, which would produce 120l in 8 hours from source water is circa 350 tds, this would be produced over night with no other water use in the house, total water used was measured in the region of 900l, produced water was 20tds.

After reading up on increasing the efficiently I recently installed a 2nd ro membrain, so I now have have 2 membrains running is series where the waste from the 1st is fed into the 2nd.

I now produce 120lt in just under 5 hours but best of all total water used has dropped to 350l. Doing this the purity of produced water has dropped to 35tds but this is a great trade off to reduce the total waste water.

2 big factors to keep in mind on the efficiency of RO systems is the incoming pressure and temperature of the supply water, these both impact the speed and efficiency of the systems.


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## Zeus. (2 Nov 2020)

papa_c said:


> My suggestion is to use a collection barrel and not feed the water directly to the tank, I use a cheap mini float valve from aliexpress, used it for the last 2 years with no issue.
> 
> With an RO unit, the RO membrain housing has 2 outlets 1 for waste and 1 for clean water.
> You must make sure the filter also has an auto shut off valve, when the collection tank is full and the float valve closes pressure builds in the clean water line which forces the auto shut off valve to close cutting the supply water, without this water will simply flow out the waste line.
> ...


I take it both membranes run off the same booster pump ?


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## papa_c (2 Nov 2020)

Yes, i have a single booster pump fitted and it works flawlessly. I simply added  the additional filter housing, was totally surprised at the reduction in waste water.


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