[pure tech]

Hi, I have just fitted a 10" Pentek CBF-Plus10 pre-filter to my 300gpd R/O (Gardiners call it a Fibredyne) and have noticed that while running, the clear housing it sits in is totally filled with water but after turning the R/O off, the housing partly drains and remains about 75% full with water.
Is this normal and could the filter get damaged if it is not totally submerged.
Any advise would be much appreciated thanks.

[Alex Gardiner]

Hi, I have just fitted a 10" Pentek CBF-Plus10 pre-filter to my 300gpd R/O (Gardiners call it a Fibredyne) and have noticed that while running, the clear housing it sits in is totally filled with water but after turning the R/O off, the housing partly drains and remains about 75% full with water.
Is this normal and could the filter get damaged if it is not totally submerged.
Any advise would be much appreciated thanks.

On some systems this can happen - it will not harm the filter at all.

[pure tech]

Thanks Alex.  I have now noticed that the housing is only about 25% full with water after the R/O is turned off.
It drains for about a minute after turning off and at the same time the R/O continues to produce from both product and waste before stopping. Do you think the three R/O membranes will stay completely wet and protected at all times?

[Alex Gardiner]

Thanks Alex.  I have now noticed that the housing is only about 25% full with water after the R/O is turned off.
It drains for about a minute after turning off and at the same time the R/O continues to produce from both product and waste before stopping. Do you think the three R/O membranes will stay completely wet and protected at all times?

It would be best if you could turn the product off with a valve once you have shut the RO off to maintain the water in the RO membrane - perhaps add one of these to the product -

[pure tech]

I had considered adding one of these valves but was worried I might forget to turn it on again when running the R/O and damage the membranes. Would you fit the valve before or after the resin? Thanks

[Alex Gardiner]

I had considered adding one of these valves but was worried I might forget to turn it on again when running the R/O and damage the membranes. Would you fit the valve before or after the resin? Thanks

I would fit this after the DI resin myself.

[pure tech]

Hi Alex, I fitted an inline valve after the resin but water was still draining from the waste line for a minute or so after turning off the R/O which was draining the pre-filter housing. So I have fitted an inline valve to the waste line as well and the system is now shutting off instantly and not drawing water from the housing.  Not sure why this has become necessary but all seems good now

[combat1]

Sounds like air in the system. I had similar problem.
Run system with booster pump off. Unscrew the filter chamber until water runs out of top. Tighten and run without pump for a while.
If the level drops again repeat the previous.