[reflect]

I’m wondering how often to change the merlin carbon filter. It says every 38,000 ltrs. I don’t know how to work this out. Is this 38,000 of pure water? Is this pure and waste together? Or is it the mains input? Thanks

[p1w1]

mains input.

[Spruce]

I’m wondering how often to change the merlin carbon filter. It says every 38,000 ltrs. I don’t know how to work this out. Is this 38,000 of pure water? Is this pure and waste together? Or is it the mains input? Thanks

Its a total of waste and pure added together. So this is a p1w1 says, the mains inlet into your r/o.

The only sure way of knowing when to change the prefilter is by fitting a sub meter before the r/o.

Something like this
http://www.ebay.co.uk/itm/15mm-1-2-Cold-Water-Meter-Garden-Home-With-Free-Fittings/321489430551?hash=item4ada436817:g:IawAAOSwCkZZOVVo

or a digital one
http://gardinerpolesystems.co.uk/digiflow-combo-meter.html

[reflect]

So it’s just a case of adding the pure and waste together. I also have a booster pump which increases the pressure to 70-80psi. Does this increase the mains flow by drawing more water through the pipes? Or is it the same flow, but it somehow concentrates the flow into high pressure

[p1w1]

this flow meter is a bit cheaper and i use the same one works well http://gardinerpolesystems.co.uk/all-products/pure-water-systems/water-treatment/tds-meters/digiflow-flow-meter-and-filter-life-monitor-with-1-2-ports.html

[Spruce]

So it’s just a case of adding the pure and waste together. I also have a booster pump which increases the pressure to 70-80psi. Does this increase the mains flow by drawing more water through the pipes? Or is it the same flow, but it somehow concentrates the flow into high pressure

Some people report that increasing the water pressure reduces the amount of waste. I can't comment as I have never had a Merlin or a booster pump.
What I do know is that a fellow windie down the road has one and his waste to pure was around 5 to 1 on our 50psi without a booster.

Gold has the PRF which is the latest model. He reports that his waste to pure is about 3 to 1. I'm not sure if that's because he has a high water pressure or if the PRF has been 'reworked' to be more economical with regard to water usage. The PRF is in competition with the 4021 which is a much more efficient r/o IMHO.

Theoretically, a booster pump shouldn't make much difference to your water consumption. The higher pressure means the filtration cycle should be shorter.

.

[Perfect Windows]

You can't smell chlorine under about 1ppm ( http://www.waterandhealth.org/drinking-water-chlorine-odor/ ) but it will still mess up your membrane.

Vin

EDIT: This looks a little out of place - it was a response to a stupid post that was later removed where someone claimed if you can't smell chlorine you shouldn't worry about charcoal filters.

[AuRavelling79]

Late to the party.

It's 38,000 litres total. A slight weakness in the system IMHO. I don't measure it but notice that the flow slows down (and the output tds creeps up) after about 6 weeks and I whack in a new one.

I think they are about £19.50 plus Vat - so about £3.25 per week.

[Spruce]

Late to the party.

It's 38,000 litres total. A slight weakness in the system IMHO. I don't measure it but notice that the flow slows down (and the output tds creeps up) after about 6 weeks and I whack in a new one.

I think they are about £19.50 plus Vat - so about £3.25 per week.

Probably not a weakness with the unit Gold but it could be due to your Bristol water quality.

Our water has above average sediment in it. At times previously I had to replace my sediment filter once a month and then the sediment and Fiberdyne on the third month.

The fellow windie who has an old Merlin had the same issue and added a sediment prefilter before the inlet to his r/o. He changes that regularily and his carbon filter lasts longer as it doesn't get clogged up with sediment. The Merlin/PRF uses the Fiberdyne carbon block filter as a conbination sediment and chlorine filter, and this is where we would have problems as the c/b would get blocked with sediment before it completed its service life.

[AuRavelling79]

Hi Spruce. I catch your drift.

I was changing at about 4/5 weeks possibly due to the high TDS and so I emailed Alex G. (who has nothing better to do than to answer my damnfool questions from time to time  ) and he suggested a paper filter before the fiberdyne in the R/O and as I had a 10" filter housing knocking about from my old system and some 10" paper cartridges (cheap as chips) I added this in line. I seem to get 7/8 weeks if I change the paper filter at the same time.

So I do get at least 38,000 litres but the Fiberdyne's an 18 incher. You can get extended life 20" for other systems but not the 18 incher. (Unless someone knows differently?)

[Perfect Windows]

Here's our solution: Works well, involves work once a year (in our case) and is pretty cheap.

http://www.cleanitup.co.uk/smf/index.php?topic=189393.msg1630974#msg1630974

Vin

[AuRavelling79]

That looks very interesting Vin. So how do you know if the charcoal needs changing? Does the flow slow down or what?

And do you not have the fiberdyne in place in the merlin or do you have one which just lasts so much longer?

Sorry for not grasping stuff too quick!

[Perfect Windows]

In honesty I have no idea when the charcoal needs changing.  There is a test kit that shows if there's chlorine in the water coming out but I just settled on changing it annually: Must be about right as the membrane's now about four years old (4040) and still giving 8ppm at an input of ~300ppm. £40 or so a year seems OK to me - even if I doubled the life of the charcoal by testing I'd only be £20 a year up. Life's too short.

I have a 20" prefilter after the charcoal. It stays perfectly clean between changes of charcoal but I check it anyway.  We have water that occasionally tastes like soil (it's a surprisingly pleasant earthy taste) and the filter used to look like this after about three months:



But now it's spotless after a year, which makes me think the charcoal's also filtering out particles.

Hope that helps,

Vin

[Brooke]

Hi,
So I've been using a merlin now for 3 years now and am more than happy with it. I change carbon filter every 38000 litres.... reason why is cause they say you should. I have several friends in the  water treatment industry and they say that after 38000 litres your carbon filter is spent and therefore ineffective. To continue using it after this will only damage your membranes which of course is a greater expense to replace. Wether or not you can get more out of it or not I don't know I just prefer not to take the chance. My TDS going in is 360 and with the merlin brings it down to 20/21 . My water pressure at unit is slightly under 50 bar. I've yet to replace my membranes on the merlin and I fill up a 500l tank 5 days a week.  As I understand it and have gone by you replace it after 38000l of water going into the unit. Hope this helps