[mac74]

Hi, i was looking at these cheap 20" pre - filters from finest filters, £35.99 for 3x sed, & 3x carb. But from back posts on here it looks like you have to change them around 12k litres ? or 12 ibc tank fills? Is this right? So if my waste to pure is, 1000L ibc tank pure, and 2000L waste (3k total). Would that mean that just 4 full ibc 1000L fill ups i would need to change the pre filters? i.e 4k L pure, add 8k L waste = 12 k Litres service life??

Is there more expensive longer life pre filters out there?

[Bungle]

I just change them when I can be arsed.

[mac74]

I just change them when I can be arsed.

Ive always been the same as that, but it might be the reason why my R.O has gone from 8ppm 5mths ago to 19ppm right now?

[Spruce]

I just change them when I can be arsed.

Ive always been the same as that, but it might be the reason why my R.O has gone from 8ppm 5mths ago to 19ppm right now?

The service life of a carbon filter is the total amount of water the r/o is processing, so waste plus pure.
I use 20" Fiberdyne c/b. It's good for 75600 litres.  They are rated at 5 to 10 micron. (The Spectrum sediment filters we use are rated at 5 micron, so anything smaller will pass through both the sediment and carbon block filter.)


There are ones that last longer but they are 1 micron and when used with a sediment filter, they block up prematurely using our water.  (Using a Spectrum sediment filter and this 1 micron c/b filter, sediment below 5 micron and above 1 micron will get caught in the carbon block filter.)

Do you need that higher waste to pure water ratio?

Your carbon filter removes chlorine from your tap water. Chlorine destroys membranes. None of us know how much chlorine is in our tap water at any particular time. Sticking to the mfg's guidelines has meant my membrane is now 11 years old and still performing at 97% efficiency. Some argue that had I not replaced my prefilters so often, I would have saved more money, even if I had to replace my membrane say every 5 years. I get that argument. It's all down to 'economies of scale.'

In my case, Northumbrian water has been our only source of supply ever since I started wfp. Initially, I purchased a used r/o which was a year old. It was also used in our area from the same water source. That cleaner never changed the prefilters in the year he had it. Those membranes had to be replaced. I then started to replace prefilters every 3 months, and the next set of membranes lasted 6 years. So I know we can't just change our prefilters once a year.

I use 20" Fiberdyne prefilters that the mfg says are good for 75,700 litres of water. I have my r/o on a water meter and change the prefilters at 77k which is approx every 3 to 4 months. If the chlorine content is much lower than the chlorine content the carbon block is tested against, (estimated capacity using 2 ppm free available chlorine at 0.5 ppm breakthrough, whatever that means,) then in theory my c/b filter should last longer. But, as I said, I have no idea how much chlorine is in my tap water at any given time, so my only option is using the mfg recommendations.

This works for me.

[mac74]

Thanks for the above reply's. Ive just got some off Finer Filters which state:  Sed = 32k L  & Carb = 29k L service life, (sounds to good to me) £15 a pair.
Ive been looking at the 20" x 4.5 Jumbo pre filters, and the carbon has a service life of 130k Litres ! Im going to look into these when i next change the R.O out. Cheers m

[Spruce]

Thanks for the above reply's. Ive just got some off Finer Filters which state:  Sed = 32k L  & Carb = 29k L service life, (sounds to good to me) £15 a pair.
Ive been looking at the 20" x 4.5 Jumbo pre filters, and the carbon has a service life of 130k Litres ! Im going to look into these when i next change the R.O out. Cheers m

How can anyone quote a service life on a sediment filter?  I've had one last a day. It's life will depend on how much sediment is in the water pipes.

[mac74]

Thanks for the above reply's. Ive just got some off Finer Filters which state:  Sed = 32k L  & Carb = 29k L service life, (sounds to good to me) £15 a pair.
Ive been looking at the 20" x 4.5 Jumbo pre filters, and the carbon has a service life of 130k Litres ! Im going to look into these when i next change the R.O out. Cheers m

How can anyone quote a service life on a sediment filter?  I've had one last a day. It's life will depend on how much sediment is in the water pipes.

I spoke to June at Gaps water today, and she told me that the fiberdyne filters wouldn't work with a booster pump, so im still looking around because changing them over is a right damn on. I have the older blue housings, in a metal top frame, and it takes a few mates to hold the unit whilst tighting the bstard up with 2 wrenches. Also when i do change the pre filters, the sediment one is white like new? 

[Spruce]

Thanks for the above reply's. Ive just got some off Finer Filters which state:  Sed = 32k L  & Carb = 29k L service life, (sounds to good to me) £15 a pair.
Ive been looking at the 20" x 4.5 Jumbo pre filters, and the carbon has a service life of 130k Litres ! Im going to look into these when i next change the R.O out. Cheers m

How can anyone quote a service life on a sediment filter?  I've had one last a day. It's life will depend on how much sediment is in the water pipes.

I spoke to June at Gaps water today, and she told me that the fiberdyne filters wouldn't work with a booster pump, so im still looking around because changing them over is a right damn on. I have the older blue housings, in a metal top frame, and it takes a few mates to hold the unit whilst tighting the bstard up with 2 wrenches. Also when i do change the pre filters, the sediment one is white like new?

I wish our water was like that. There are a few others in our area who wish the same.

[mac74]

That service life on those fiberdyne carbon filters is very good, but i use a booster pump too. So maybe i could try it with the booster pump in between the pre filters and the R.0? instead of before the pre filters. (So the Fibredyne wont collapse? says GAPS water?)  My sediment filter has always been clean when i replace it, so maybe this would work for me? Cheers 4 replys m.

[Spruce]

That service life on those fiberdyne carbon filters is very good, but i use a booster pump too. So maybe i could try it with the booster pump in between the pre filters and the R.0? instead of before the pre filters. (So the Fibredyne wont collapse? says GAPS water?)  My sediment filter has always been clean when i replace it, so maybe this would work for me? Cheers 4 replys m.

These companies have to ensure they protect themselves when giving advice, so they give advice that pertains to the worst case scenario.

June has been with GAPS for years, so has a wealth of experience and knowledge.

My logic tells me that as most carbon prefilters are 5 micron, this problem of collapsing should be a common problem. But it isn't judging by forum topics.

IMHO the best place to fit a booster pump is after the prefilters and before the membrane, but if I was fitting one I would probably opt to put it before the prefilters. Our water isn't the best, and we do suffer for a reduce flow through the sediment filter when it starts to block up. So doing this would mean the booster pump was 'pushing' rather than 'sucking' through the prefilters.

According to the water regulations, a booster pump mustn't draw more than 12lpm of water from the main supply. One of the reasons being that doing this can damage the supply pipework and also deprive other houses on the ring main of water. In the days Gardiners sold prefilters and a booster pump, Alex recommended the booster pump be switched off when flushing. One of the reasons would be that the 12lpm limit could be compromised. The problem June has highlighted isn't only a prefilter issue.

The trouble with all of this is that a sediment filter can block up in a couple of hours as I have experienced. It was only once in 17 years though. But I regularily had to change the sediment filter before the carbon block during those 17 years. Saying that, our water quality has got better recently. I've got 24k left on my current carbon block filter, but the sediment filter is looking very discoloured.