Is my membranes broken

[Amos]

Hi guys had an empty tank last night put new resin in filling up checked ppm it was 000ppm checked this morning got about 400 L in the tank and PPM at 14 so is it my membranes gone thanks for any help as absolutely rubbish at the mechanics of these things !!

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[Dave B]

What ro do you have?

If it's a 4040 disconnect the pipe to the di and take the tds of that

If it's a 450 disconnect each output 1 by 1 from all 3 membrane housings and check the tds of each one

If the tds is higher than 4% of the tds of your supply the membranes are not working properly

I had the same issue this week and tested the output before di and it had shot up to 37ppm

New membranes and resin now ordered

@spruce i would guess 96% rejection rate is on the high side how high would you let it go?

 

[Part Timer]

Spruce is the man but I would've thought if you've put new resin in then that should clean it initially even if filters are on their way out. My first thoughts are you've not filled resin bottle correctly. Check water before resin. 

 

[spruce]

What ro do you have?

If it's a 4040 disconnect the pipe to the di and take the tds of that

If it's a 450 disconnect each output 1 by 1 from all 3 membrane housings and check the tds of each one

If the tds is higher than 4% of the tds of your supply the membranes are not working properly

I had the same issue this week and tested the output before di and it had shot up to 37ppm

New membranes and resin now ordered

@spruce i would guess 96% rejection rate is on the high side how high would you let it go?

This is a difficult question to answer and would depend on your initial tds. I asked this same question many years ago  when I first started and Peter Fogwill said that 94% efficiency was when to consider changing membranes.

Over the years I set my sights higher than that. My reasoning is that the membranes will steadily start to become less efficient and you are going to have to change them anyway. The longer you procrastinate the higher your resin costs. 

My very first membranes dropped of the cliff (a Formula 1 description of how a tyre could perform well and then within a lap become virtually un-driveable.) That r/o only had a small 10" di vessel and I was changing the resin everyday just to get me 350 liters. I ordered new 150gpd membranes from RoMan but had to wait as they were expecting a shipment from the USA. (150gpd membranes were also a new product and they were the only ones who stocked them.) I saw how quickly they became u/s and I saw how much resin I was using to polish the water off.

Saying that the early Merlins were only removing 90% of the dissolved solids right from new. I saw how much resin a fellow cleaner was using just to polish the 25ppm that his r/o wasn't removing.

.

 

[Dave B]

That is the problem i had

Hadn't checked pre di tds for a while (lesson learnt)

Killed my resin which was the expensive tulsion stuff (can't remember the name but more expensive than mb-115 that i got off a mate already in the di i bought off him

Was old stuff but would have lasted a lot longer with lower tds going through it

 

[spruce]

That is the problem i had

Hadn't checked pre di tds for a while (lesson learnt)

Killed my resin which was the expensive tulsion stuff (can't remember the name but more expensive than mb-115 that i got off a mate already in the di i bought off him

Was old stuff but would have lasted a lot longer with lower tds going through it

My experience is that membranes seem to work faultlessly for years and then suddenly start to degrade very quickly. I don't check the tds of the water in the van's tank often. I used to in the early days but have got rather complacent or lackadaisical over the years. I have an inline tds meter so know what my r/o is performing at and also the tds after di at the touch of a button, but don't remove the front panel of the cabinet as often as I should to access that info.

I need to be more diligent as my membrane is 5 years old. The previous 450gpd r/o membranes lasted me 6 years.

 

[Amos]

Different class guys I have just put more resin in as I'm doing a very posh American school ! Tds reading before going into resin is 40 is that ok or not ?


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[spruce]

Different class guys I have just put more resin in as I'm doing a very posh American school ! Tds reading before going into resin is 40 is that ok or not ?


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Didn't you buy a used r/o @Amos?

Your r/o output of 40 is too high. Membranes, when working efficiently, will remove between 97 and 98% of the dissolved solids in your tap water. So if your tap water has a tds of 350ppm, then the output before di should be between 7 and 11.

If you have good water pressure and good water flow from your tap, then you r/o membrane/s are suspect and probably need replacing.

 

[Amos]

Thank you spruce sorry to ask but where would the best place to buy 2 x 300 god membranes?


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Gpd


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[Amos]

Thanks part timer , what do you mean by not filled resin bottle correctly?


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[spruce]

Thank you spruce sorry to ask but where would the best place to buy 2 x 300 god membranes?


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Gpd


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They aren't very popular and not many of the main suppliers sell them. Hopefully someone else who has the same system could make a suitable suggestion.

I don't know who makes this one or what their quality is;

http://thecleaningwarehouse.co.uk/300-gpd-ro-membrane-2151-p.asp

or this;

http://www.vyair.com/Scripts/prodView.asp?idproduct=407

Streamline also sell these membranes.

http://www.varitechsystems.co.uk/products/reverse-osmosis-systems/8/filterplus-ro-membrane/3631

Interestingly, their 2017 paper catalogue lists the membrane under Filmtec R.O. Membranes, a good quality American sourced membrane. The photo of the membranes is too small to see the manufacturer on it. If you look at the webpage the same part no R-MR300 shows the photo of a Vontron membrane which is a cheaper Asian copy. One of the suppliers noted on a smaller 150gpd Vontron membrane was that its efficiency and longevity was below that of an Axeon membrane, another quality USA sourced membrane.

My gut is telling me to suggest that you replace the membrane housing with one of these;

http://gardinerpolesystems.co.uk/all-products/pure-water-systems/water-treatment/ro-housings-membranes-parts/3012-500-reverse-osmosis-membrane-housing.html

and order a single membrane,

http://gardinerpolesystems.co.uk/all-products/pure-water-systems/water-treatment/reverse-osmosis-membranes/axeon-hf5-3012-12-ro-membrane-500gpd.html

It would produce water a little slower but at least you will get a good membrane. If you went this route you would also need to ascertain that the pipework would be interchangeable, ie. 3/8" tube.

Edit;

I found their assembly instructions that list their piping as 1/4" so my suggestion would make things more complicated.

Sorry.

.

 

[Amos]

Different class thanks spruce soo helpful.


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[Part Timer]

Thanks part timer , what do you mean by not filled resin bottle correctly?


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As you've said your tds is 40 then either your water pressure is to low or your membrane is cattled. If you hadn't reassembled the DI correctly I believe water can bypass the resin. 

 

[Tuffers]

What is your tap psi @Amos? My tap psi was 20 a week ago, it's now shot up to 60.