How often should you change gac filters

[M DUNCAN]

How often should you change gac filters? 

It says they need changing more often than normal carbon filters 

 

[spruce]

How often should you change gac filters? 

It says they need changing more often than normal carbon filters 

On our last GAC 20" filters the label says 2500 gals. As those are American gallons that's 10,000 of both waste and pure produced.

The label on the 10" GAC filters also says 2500 gals.

 

[Den]

On our last GAC 20" filters the label says 2500 gals. As those are American gallons that's 10,000 of both waste and pure produced.

The label on the 10" GAC filters also says 2500 gals.

Spruce I didn’t think the GAC filter was needed just the carbon and sediment that’s requred for the protection or the membrane.

 

[spruce]

Spruce I didn’t think the GAC filter was needed just the carbon and sediment that’s requred for the protection or the membrane.

It will also remove chlorine from the water if you don't have a carbon block filter. TBH I used a sediment and a GAC filter for 3 or 4 years with my 450GPD and those membranes lasted 6 years. (Those r/o's that still have 3 prefilters usually had a sediment, a carbon block and a GAC filter. Having the c/b and the GAC filter combination increases the service life of the chlorine removal properties of those filters.)

When I first assembled my 4040 I ordered GAC filters like I had always done before. The first 20" filters that came had the label indicating a service life of 10,000 liters. That wasn't good enough so I found the newly introduced Fiberdyne filters which I have used ever since. I still have one remaining GAC filter under my desk that is 6 years old now.

So when it comes to water purification to be used for drinking water, then the GAC filter does make the water taste better and does remove odour. So it makes coffee and tea taste nicer. When used for drinking water purification the pure isn't put through a final resin filter as that is not necessary or healthy - you wouldn't drink r/o water used for window cleaning unless you were dying of thirst.

 

[M DUNCAN]

That’s great thanks mate, this water purification is a lot more complicated than you think, as soon as I see the slightest mark on my windows I start panicking thinking I need to change my filters! ?

 

[Den]

It will also remove chlorine from the water if you don't have a carbon block filter. TBH I used a sediment and a GAC filter for 3 or 4 years with my 450GPD and those membranes lasted 6 years. (Those r/o that still have 3 prefilters usually had a sediment, a carbon block and a GAC filter. Having the c/b and the GAC filter combination increases the service life of the chlorine removal properties of those filters.)

When I first assembled my 4040 I ordered GAC filters like I had always done before. The first 20" filters that came had the label indicating a service life of 10,000 liters. That wasn't good enough so I found the newly introduced Fiberdyne filters which I have used ever since. I still have one remaining GAC filter under my desk that is 6 years old now.

So when it comes to water purification to be used for drinking water, then the GAC filter does make the water taste better and does remove odour. So it makes coffee and tea tast nicer. When used for drinking water purification the pure isn't put through a final resin filter as that is not necessary or healthy - you wouldn't drink r/o water used for window cleaning unless you were dying of thirst.

I’m still using my Gpd450 and have been using fiberdyne and sentiment and still have a couple left but can get  a load of 10” carbon filter for under £1.70 each was thinking of getting them and changing them every two weeks or would you advise sticking with fiberdyne?

 

[spruce]

I’m still using my Gpd450 and have been using fiberdyne and sentiment and still have a couple left but can get  a load of 10” carbon filter for under £1.70 each was thinking of getting them and changing them every two weeks or would you advise sticking with fiberdyne?

The problem is that you can easily loose track of when you you should have replaced them.

I know I forgot to replace the GAC filter once or twice and that could have hastened the demise of my 6 year old 150gpd membranes - but then maybe it was only age related, I don't know. This was one reason why I fitted a water count down meter with an audible alarm.

I've recently noted that the manufacturer doesn't know how much chlorine is in anyone's water at any given time. So they go with a maximum possible amount and base their service life calculations on those.  @doug atkinson once stated that the chlorine concentration in your water weakens the further you get from the dosing station. Now try to find out where your water boards dosing station is. I asked numerous Northumbrian Water Board employees but no one knows. One guy apologised - he had worked for NW for 30 years - since he left school - and he admitted he didn't know.

The last chap I asked was digging up to lay some new pipes - surely he would know. He looked at me blankley and asked what chlorine was. My response was "never mind." He then looked at me as though I was the one who was dof (South African slang for stupid.)

So if your chlorine concentration in your water is half of that the calculation is based on then in theory your filters should last twice as long.

Some windies only replace their cheap prefilters every 3 or 4 months, some every 6 months and their membranes last a long times. Others aren't as fortunate but they play the sliding game of economies of scale. In some cases its costs less overall by cutting back on regular prefilter changes as you are still better off financially even having to replace membranes sooner.

But for me, I will stick with what works for me. I will continue to use Fiberdyne filters and will change them when they say I should.  And I will advise others to do the same - follow the manufacturer's instructions.

 

[Den]

Thanks Spruce love your in depth and honest answers I always benefit from them ?

 

[spruce]

That’s great thanks mate, this water purification is a lot more complicated than you think, as soon as I see the slightest mark on my windows I start panicking thinking I need to change my filters! ?

It doesn't help that most r/o's were once sold for purifying water for drinking and for fish keeping. These suppliers then discovered that the biggest growth industry was selling r/o's into the window cleaners market. So they targeted our industry with the same equipment they sell to all other industries.

But do they care they we require a better quality of product for our use? No, because they know that their r/o's are cheaper than r/o's fitted with more efficient membranes and window cleaners mostly consider the purchase price of paramount importance when making a buying decision. We see it all the time.

Take for example our old friend the Merlin r/o. It was designed for an under counter kitchen appliance for the American market. For its purpose its a brilliant piece of kit. The pure outlet from the r/o goes to a third kitchen tap. When you open the tap the release of pressure switches the r/o on and you get pure, filtered water out of that tap. Switch the tap off and the r/o shuts down. The membranes in the r/o aren't very efficient, they don't need to be. If they only remove 85 or 90% of the dissolved solids in the water, that's fine. Leaving some minerals in the water is a good thing for drinking water.

The suppliers now see a new market to sell their product - window cleaners. The benefits of a Merlin is that you just need a ball valve in your IBC storage tank for the r/o to work. Take water out of the IBC tank, the ball valve opens and the r/o starts producing pure water filling up the IBC tank. Once full the ball valve shuts and the r/o switches off. Lets sell this plug and play r/o to window cleaners.

But window cleaners use a lot of water and we need an efficient membrane/membranes. We need to remove as much of the dissolved solids in the water as possible because we work with pure water. To achieve pure water - 0ppm - we polish the remaining tds after r/o with resin beads. So atm my Axeon membrane is removing 97% of the dissolved solids in our water. Our tds is currently 123 ppm but it fluctuates between 79 and 150.  Currently we use about 8000 liters of pure water a month window cleaning. Thats 96000 liters a year. That costs me about £20 a year in resin to polish that water off according my running costs.

My mates Merlin is removing 87% of the dissolved solids from the same water supply - he lives a couple of stone throws away. His pure water after r/o isn't as pure as mine is. If I was using his r/o, then my resin costs will be £87.00 a year. So my current much more efficient r/o has saved me £402 on resin alone over the past 6 years. Now his r/o wastes a lot of water than mine does. For every 1 liter of water he produces his r/o sends 5 liters to waste.

My r/o produces 1 liter of pure and sends 1 liter to waste. My water consumption is about 192000 liters per year. Had I been using his Merlin I would have used 576000 liters. The difference in water consumption to achieve the same result is 384000 liters. On a water meter that extra waste water will cost a fortune. Now, because my Merlin is using so much more water I need to replace my carbon block filter much more regularily, again adding addition cost to producing water.

.

 

[CleanerWindows]

Your bang on there@spruce. [emoji108]

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