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when to change filters?

trevor peacock

Active member
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264
Location
littlehampton
I know it's been asked before but I can't find the thread!!!

I bought a 450gpd system from colins water products, I've read negative stuff about colin but I found him helpful.

I only use 2000lts a month, I bought the system in June changed the prefilters in september ( using colins ones) and my tds is up to 28, ( 330 tap water).

when should I change the ro filters and which are the best ones to get?

I think spruce said to avoid cheap ones like the ones colins sell as it's a false economy.

 
Spectrum approx below:

Filter change frequency based on average daily use:

Carbon Pre-Filter: Every 6 months

RO Mebrane: 18 months or more often based on your local water.

Carbon Post-Filter: Every 6 months

You'd have to look at Colins recommended to get the best answer.

 
I know it's been asked before but I can't find the thread!!!I bought a 450gpd system from colins water products, I've read negative stuff about colin but I found him helpful.

I only use 2000lts a month, I bought the system in June changed the prefilters in september ( using colins ones) and my tds is up to 28, ( 330 tap water).

when should I change the ro filters and which are the best ones to get?

I think spruce said to avoid cheap ones like the ones colins sell as it's a false economy.
Hi. Your membranes should have lasted longer than 6 months - even those Collins sell.

Your membranes are showing an efficiency of just under 92% which is well below what you should expect IMHO. Of course I don't know the exact reason why the r/o isn't performing and there are many factors that can cause the problem from operator error, reduced supply water pressure to faulty products. (It wouldn't be the first time someone took the pipes off and accidentally connected a waste pipe from one of the membrane housings to the pure from the other 2 when reassembling them.)

I presume that you have an r/o with 3 membrane housings, each with a 150GPD membrane fitted. What I would do is carefully mark each housing with the inlet, outlet to waste and outlet to pure. Its always good to take lots of photos on your phone. Then take it all apart and run one membrane housing at a time to see if the fault is just with one membrane or not. By taking pure readings you will be able to identify the faulty membrane as it will read a high tds where the others won't.

I don't know how Collin's Water configures their r/o's so please bear with me. There are 3 ways that suppliers can configure the r/o membranes.

1. Prefiltered water (tap water that's come from the tap and past through the sediment and carbon prefilters) is divided into 3 pipes and each pipe supplies each membrane. All the waste pipes are joined together, go through a restrictor or tap and then go to the drain. All the pure outlets are joined together to go to the di and then onto storage.

2 . The prefiltered water is divided into 2 pipes which go to the first 2 membranes. The wastes from those 2 membranes are joined together and fed into the inlet of the 3rd membrane. The waste from the 3rd membrane goes to a restrictor/tap and then onto the drain. The pure from all 3 membranes goes to storage via the di.

3 The prefiltered water goes into the 1st membrane, the waste from the first membrane goes to the inlet of the 2nd membrane and the waste from the 2nd membrane goes into the inlet of the 3rd membrane. The waste from the 3rd membrane goes to the restrictor/tap and then to the drain. Again all 3 pure outlets go to the storage tank via the di.

The first setup means each membrane gets the same water tds of 330ppm to purify.

The second setup means the first 2 membranes get 330 ppm water to filter, whereas the 3rd membrane gets a much higher tds of water to purify.

The third setup means that the 2nd membrane has a higher tds to purify and the 3rd membrane even higher.

So with both the 2nd and 3rd setup there is going to be one membrane that is going to be hammered.

The reason why some suppliers choose the 2nd and 3rd method of piping is that they can reduce the amount of waste water going to the drain so can save water and reduce processing costs. It also means they can make the r/o cheaper as they aren't using as many John Guest T fittings as they are with the 1st setup.

If all 3 membranes are showing a high pure output tds then it could have been an issue with the carbon prefilters. On the old r/o 450GPD that we had, we fitted 2 rubber sealing rings at the top to prevent 'raw' water bypassing the carbon block. That water wouldn't be relieved of its chlorine and the chlorine would then destroy the membranes.

Another problem is that r/o's like to work. Over the last 6 months you have used so little water that yours is still asleep.

.

 
Last edited by a moderator:
Spectrum approx below:
Filter change frequency based on average daily use:

Carbon Pre-Filter: Every 6 months

RO Mebrane: 18 months or more often based on your local water.

Carbon Post-Filter: Every 6 months

You'd have to look at Colins recommended to get the best answer.
You'd have to look at Colins recommended to get the best answer.

The trouble is that Collins don't sell r/o's geared to window cleaners requirements. They have just started selling 4040's for window cleaning but their systems need refining as they aren't at our level of requirements yet IMHO.

.

 
You'd have to look at Colins recommended to get the best answer.

The trouble is that Collins don't sell r/o's geared to window cleaners requirements. They have just started selling 4040's for window cleaning but their systems need refining as they aren't at our level of requirements yet IMHO.

.
But the OP uses 2000lts a month so I'd say that's easily within average daily use of people with just RO systems set up for domestic use don't you think?

 
Hi. Your membranes should have lasted longer than 6 months - even those Collins sell.
Your membranes are showing an efficiency of just under 92% which is well below what you should expect IMHO. Of course I don't know the exact reason why the r/o isn't performing and there are many factors that can cause the problem from operator error, reduced supply water pressure to faulty products. (It wouldn't be the first time someone took the pipes off and accidentally connected a waste pipe from one of the membrane housings to the pure from the other 2 when reassembling them.)

I presume that you have an r/o with 3 membrane housings, each with a 150GPD membrane fitted. What I would do is carefully mark each housing with the inlet, outlet to waste and outlet to pure. Its always good to take lots of photos on your phone. Then take it all apart and run one membrane housing at a time to see if the fault is just with one membrane or not. By taking pure readings you will be able to identify the faulty membrane as it will read a high tds where the others won't.

I don't know how Collin's Water configures their r/o's so please bear with me. There are 3 ways that suppliers can configure the r/o membranes.

1. Prefiltered water (tap water that's come from the tap and past through the sediment and carbon prefilters) is divided into 3 pipes and each pipe supplies each membrane. All the waste pipes are joined together, go through a restrictor or tap and then go to the drain. All the pure outlets are joined together to go to the di and then onto storage.

2 . The prefiltered water is divided into 2 pipes which go to the first 2 membranes. The wastes from those 2 membranes are joined together and fed into the inlet of the 3rd membrane. The waste from the 3rd membrane goes to a restrictor/tap and then onto the drain. The pure from all 3 membranes goes to storage via the di.

3 The prefiltered water goes into the 1st membrane, the waste from the first membrane goes to the inlet of the 2nd membrane and the waste from the 2nd membrane goes into the inlet of the 3rd membrane. The waste from the 3rd membrane goes to the restrictor/tap and then to the drain. Again all 3 pure outlets go to the storage tank via the di.

The first setup means each membrane gets the same water tds of 330ppm to purify.

The second setup means the first 2 membranes get 330 ppm water to filter, whereas the 3rd membrane gets a much higher tds of water to purify.

The third setup means that the 2nd membrane has a higher tds to purify and the 3rd membrane even higher.

So with both the 2nd and 3rd setup there is going to be one membrane that is going to be hammered.

The reason why some suppliers choose the 2nd and 3rd method of piping is that they can reduce the amount of waste water going to the drain so can save water and reduce processing costs. It also means they can make the r/o cheaper as they aren't using as many John Guest T fittings as they are with the 1st setup.

If all 3 membranes are showing a high pure output tds then it could have been an issue with the carbon prefilters. On the old r/o 450GPD that we had, we fitted 2 rubber sealing rings at the top to prevent 'raw' water bypassing the carbon block. That water wouldn't be relieved of its chlorine and the chlorine would then destroy the membranes.

Another problem is that r/o's like to work. Over the last 6 months you have used so little water that yours is still asleep.

.
The pipework is configured to split to all 3 membranes equally and then reduced back to 1 pipe for waste and 1 for pure so none of the membranes should get hammered more than the others

I have a collins 450gpd and as far as i am aware as it is second hand the membranes are now over 2 years old and still producing pure at a good tds

 
But the OP uses 2000lts a month so I'd say that's easily within average daily use of people with just RO systems set up for domestic use don't you think?
Sorry, you are right. I read it as 2000l since he got it. No idea where that came from.:confused:

 
The pipework is configured to split to all 3 membranes equally and then reduced back to 1 pipe for waste and 1 for pure so none of the membranes should get hammered more than the others
I have a collins 450gpd and as far as i am aware as it is second hand the membranes are now over 2 years old and still producing pure at a good tds

The best way. Thanks for that @daveyboy. So its either a faulty membrane or if they are all performing badly then something has happened at the carbon block side of the prefilter.

 
Iv got the collingswaterproducts 450 gpd and the membranes should have lasted a lot longer than that. Was your tds high or did you just change them as a frequency thing. Iv had my filters in that long I can't remember how old they are. My Tds is around 360 at the tap after filters 004 . And is running at 50/50 pure to waste. As far as I'm concerned great bit of kit and a great guy for help and support.

 
Last edited by a moderator:
Iv got the collingswaterproducts 450 gpd and the membranes should have lasted a lot longer than that. Was your tds high or did you just change them as a frequency thing. Iv had my filters in that long I can't remember how old they are. My Tds is around 360 at the tap after filters 004 . As far as I'm concerned great bit of kit and a great guy for help and support.

 
just measured my water, I use a 80psi pump to ensure maximum performance!!!

I get 1lt of waste at 383ppm, 1.5lt good at 24ppm. My tap is 340ppm.

I've just ordered another tds meter as my old one is 12 years old and could be dodgy perhaps?

 
my ratio is 60% good to 40% waste, could that be a factor?
I would say that at 340 ppm of tap water the ratio needs to be the other way around - 60 waste to 40 pure. When we ran a 450GPD the inline restrictor was set at 3 waste to 1 pure. (So to produce liter of pure we used 4 liters of tap water.) At one time RoMan used to sell another restrictor for high tds water supplies - its was 5 waste to 1 pure.

The ratio you are using will save water if you are on a meter, but premature membrane failure must be expected. As with most things, its a tradeoff of costs. You could spend thousands trying to prolong the length of the life of your membranes when replacing them will cost much less overall.

.

 
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I use approx 1600 ltrs a week and have never changed my ro filter yet (cleaning for 4 years now ) replaced pre- filters approx 8 times and resin 5 times using a brodex machine [emoji16]

Sent from my SM-G930F using Tapatalk

 
iv never checked my water pressure. Iv never had a problem with water production or quality and as the old saying goes if it ain't broke.

 
i have the 4021 and in the 5 years ive had it i changed the membrane just once and the pre filters never. still get water coming out at around 28-50 depending on the temperature of the water. i produce about 900L a week.

 
i have the 4021 and in the 5 years ive had it i changed the membrane just once and the pre filters never. still get water coming out at around 28-50 depending on the temperature of the water. i produce about 900L a week.
You need to change your prefilters regularly. The carbon block removes chlorine from the water. Chlorine destroys membranes.

 
It's not really going ok if it's producing that high

It should be producing around 97% efficiency so 3ppm per 100ppm going in from the tap

300ppm should be giving you 9ppm out ish..not 28ppm on a good day

Makes a big difference in resin cost compared to the cost of pre filters

 
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