[Davew]

Mine have a sticker on saying max life six months. I'm going to change them this week , do any of you leave yours longer or would it just be false economy?

[Alex Gardiner]

The sticker is correct, they need changing at least every 6 months, 4 months would be even better. Leaving them longer is a false economy as they stop protecting your RO membranes and will lead to a shorter life on them. Years ago I found out the hard way and didn't change the pre-filters often enough, this led to membrane failure after about 14 months. (I was a newbie and the WFP supplier I had bought all my equipment from, gave no maintenance instructions!)

[Davew]

So my next question: how long can I expect my membranes to last? High tds (above 300).

[Alex Gardiner]

If you change your pre-filters regularly and flush your system regularly (best to flush for 2-5 minutes before each major tank fill) then you should get 2 years out of them. You can soon tell when they need replacing as your output TDS will start to creep up and the production rate will fall.

[Spursboy1972]

Does this mean that you should replace your pre filters at regular intervals regardless of how much use they have and regardless of what the TDS output reading is?

[Alex Gardiner]

Pre-Filters do need changing regularly, but it is partially dependant on the use they have. If you only process 500 litres a week then 4-6 months is fine but if you process 2000+ litres then 3-4 months would be advisable.

It would always be advisable to change the pre-filters every 6 months regardless of the use they have had because they will have been sitting in water in the canister for that time which will have had an effect on their integrity.

The Pre-Filters should be changed regardless of the output TDS. Once output TDS rises it means that more strain is being put on the RO membrane already which will eventually have an effect on the life-span of it. Ideally they should be changed before TDS rises.

[Spursboy1972]

Thanks for the reply Alex

At present I am producing between 500- 100 ltrs per week. So an average of 700 I guess.

I have an RO system that I bought 2nd hand where the resin, pre-filters and membrane had all been changed. I bought this in May this year.

Up until about a month ago I had been producing water with an output TDS reading of 000. This then went to 002 and is now on 004.

Assuming I am nearing the time to change the filters there are a few questions I have.

1) The best place to get the pre filters from? (20 inch)

2) Is there a specific procedure to follow when changing them?

3) Do I need to flush the system through or will my TDS reading automatically come back down?

Any help appreciated.

[Alex Gardiner]

Hi Tony,

Assuming I am nearing the time to change the filters there are a few questions I have.

1) The best place to get the pre filters from? (20 inch)

2) Is there a specific procedure to follow when changing them?

3) Do I need to flush the system through or will my TDS reading automatically come back down?

Any help appreciated.

1) Us naturally

2) Just unscrew and replace. Make sure that the rubber 'O' ring is seated back in the right place before screwing the canister back onto the lid.

3) Yes you will need to flush the system through. Simply turn your valve to flush mode and allow the unit to flush for about 2-5 hours. If you have no flush valve then disconnect the outlet from your Pre-filters before it gets to the membrane and let it pour down the drain for about 1-2 hours.

[Spursboy1972]

Hi Alex

Thanks once again for the info. Are all 20inch filters standard? If so can you give me a price for the 3 filters please inc delivery to Southampton. If you need me to I will take pics of the housing and the one spare filter I have to assist further.

My system backflushes automatically so I will need to check if there is a valve to turn and if not then I will work out how to disconnect the outlet. That is assuming they run in aline or that the tube goes form the 3rd pre filter into the membrane. If thats the case then it should be straight forward.

Apologies for my total ignorance and acting dumb but I am blonde!!

[Alex Gardiner]

Hi Tony

Sorry for the delay in getting back to you.  I have checked with Kirsty (she runs the business) and she says she can easily supply all three.  Give her a ring on 01726 61143 during office hours.  If she's not there, leave a message and she will get back to you.