"Pszemol" wrote in
:

"Mark Cooper" wrote in message
.. .
I've gotten a Kent Hi-S RO unit from a buddy who has gotten out of
keeping fish. He said this is a 35 gpd unit, but I'm not so sure of
that. It only takes it about 4 hrs to fill a 13 gallon container, so
I wonder if it's not actually a 60 or 75 gpd unit.

Are you sure you did not mix product and waste water outlets ?
The slow-flowing is the product, clean water. Fast flowing is the
waste (brine). KENT full size RO units are "Available in 35, 60 and
120 GPD Units, in clear canisters"
http://www.kentmarine.com/waterfilters/fullhis.html It is highly
unlikely you will get nominal output of 60gpd from a 60gpd unit
because the input tap water is usually colder than optimal temperature
and lower pressure than optimal for membrane. You should expect
normally about 70-80% (or less!) of the nominal output in real-life
scenarios. So my bet would be - based of amount of water you created -
you get the brine/product outputs mixed or... this is 100gpd unit.

There could be other thing, also - one of the seals could be leaking.
The best way to test if filter is working is to test conductance of
the water coming out of RO filter (before DI stage, if such stage
present). The TDS meter should read a value close to zero ppm (usually
less than 10ppm depending of your incoming tap water hardness). Also,
I would recommend replacing prefilters, especially the carbon filter -
if it is old and lets chlorine go to the membrane it will damage the
membrane.

How long does the membrane in this unit last? Marinedepot website
says 3 to 5 yrs, but they want to sell more, so wondering if that's a
low estimate of the useful life for the membrane?

This estimate is about right and you could shorten the membrane life
mishandling it (like keeping it dry etc).


I checked the lines and they are connected right, lots of waste water
compared to a drip drip drip of product. I think my buddy just remembered
wrong as to what unit he has. I estimate it's putting out about 40 gpd,
which seems realistic for a 60 gpd??

He said he replaced the cartidges a few months ago, so I think I probably
have a few months of use out of them. It was never allowed to go dry, so
I think the membrane and cartridges should be fine.

Regarding the membrane, he had the unit hooked up to a float valve, so
when the storage tank got full it would shut off flow. Would this extend
the operational life of the membrane, since it wasn't processing all the
time?


Thanks,
Mark