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 Post subject: RO with very high waste
PostPosted: Sat Apr 04, 2015 1:25 pm 
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HI
I realized when I tried to set up my RO waste to feed a tank to keep blackworms in that my waste stream was huge. It is a 150 GPD unit from December 2012 with the prefilters changed out if not perfectly regularly. The production of "good " water which still is at 6 TDS is Ok but the ratio of good to waste is 1:8.
Lots of people who follow this website use ROs .What have they found as regard to this type of failure. My local "guru" ,a salt water reef guy who built this unit, indicates that the membrane is likely OK.
I am thinking just to buy a new membrane and see if the waste level goes down.The waste stream was always a bit high but ,now ,it is ridiculous. THe pressure is 75 down to 55 on my well head.

Thanks Al


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PostPosted: Sun Apr 05, 2015 6:39 am 
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Location: Somerset West, South Africa
Hi Al,

Good to hear from you, let me see if I can help as the scientific advisor to the forum.

During the water purification process, forcing the water through the RO membrane does require a certain amount of pressure as you indicate. I do not know which units of pressure you refer to on your well head, and therefore if this is enough. If your tapwater does not have enough pressure, or if your membrane is blocked with particles, then the ratio of purified water relative to waste is low, precisely what you are finding. What you also need to ensure is that the waste outlet is restricted, in other words forcing the water through the membrane rather than to waste. I would check the throttle valve of your unit, that is if it can be regulated in the first place. A good RO unit should have a 1:1 purified water to waste ratio, so the 1:8 ratio does sound excessive.

It may also be that your input water is loaded with particles and that the prefilter is becoming blocked very rapidly. This in turn may be reducing the water pressure in the RO unit as such, which then means that the amount of purified water is reduced because of the pressure reduction as you indicate. Another factor that can reduce pressure inside the system is that the pipes from the prefilter to the main unit are very narrow and these then reduce the water pressure. Is there a way for you to measure the pressure of the water before the prefilter, and then again after the prefilter in the main RO chamber. This would tell us which filter may be blocked.

Other than leaks somewhere in the system, there is no other logical explanation for your problem.

Keep us updated and bounce your thoughts off us, I am sure we can get this sorted out, there is no reason why a RO unit should not work.

Kind regards,

Dirk

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PostPosted: Mon Apr 06, 2015 5:40 am 
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HI THanks for the info. The well head pressure is 75-55 pounds per square inch. That is high for a home well around the great lakes..they are usually set to 40:60 on:off. THe 150GPD RO unit is indicated to need 65lbs pressure though my reef guy/dealer says that everyone is running them at 40:60 anyway. I do I just jack my pressure switch up a bit to get more pressure.The well pump ( a submersible) is rated at 100lbs/.

I will replace the prefilters as there is iron in the water that escapes the iron remover that is ahead of the RO system and it has stained the prefilter particulate block red. Also, the iron remover machine is persnickety and is always malfunctioning and needing attention from Culligan the softener people. When it malfunctions it, of course, dumps iron into the downstream into the house. I also will check the pressures as I have just ordered an inline pressure meter which looks as if it would work perfectly for that job. A blocked prefilter could be it.
There is no throttle valve. I just open a designated Fawcett on full. THe waste restrictor is in place in the correct spot. There is a bypass/wash valve assembly on the RO unit and I do use it. By the way,there is a second RO unit ( 100gpd),fed by the same Fawcett and often both are going. THis one ,with a membrane replaced the same date as I got the 150 GPD one, remains working fine . It's prefilters are just as stained as the malfunctioning one.

A related point: I have heard it stated that activated carbon "bothers" discus. THe iron remover unit is nothing more than a gigantic cylinder of pressurized activated carbon..so everything in the house is precarbon filtered. If it does bother them, then my discus and altums are subjected to an industrial carbon filtration/adsorption, followed by the carbon block as it goes into the RO, then it is ROed then it is remineralised with calcium chloride and magnesium chloride and I add Kent trace elements. I have always wondered if it bothered the discus after all of that as sometimes they "sulk". THe altums seem totally at ease and ,on a day to day basis, seem more tolerant than the discus.
I do need to make make about 100 gallons of RO water a day to keep up so these RO units are working. Remineralizing the water from a different starting point each time (depending on the previous use,) is a bit of an art form and mistakes are made over time though I have gotten pretty good at it.
Al


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PostPosted: Fri May 01, 2015 12:58 pm 
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Quick update for those who still have GE Merlin units (like me). Looks like we will be abandoned to our luck as of October of this year. Though I don't have the link at this moment, I read Hydrologic, who took over the Merlin products line from GE and after Pentair, will no longer provide replacement products for our filters. The idea of course is to lure us towards the newer Hydrologic Evolution line, which is essentially an improved Merlin, giving us what seems to be a better performing manifold and a higher production rate from the membranes.

It also has a 1:1 product to concentrate ratio by means of a new drain fitting: http://www.hydrologicsystems.com/produc ... _3/8%22_QC

This would put the Evolution and Merlin at the lowest waste rates we can get when it comes to this class of RO units.

I am not 100% positive, but almost sure Evolution membranes and the 1:1 waste ratio fitting can be directly installed on a Merlin. And I'm tempted to find out the hard way, testing it myself.

I'm not easily convinced by the manufacturers or sellers when their first interest is pushing their new products.

This said, if money spared in my pocket, I would already have a Hydrologic Evolution.

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PostPosted: Fri May 01, 2015 1:14 pm 
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mirador wrote:
HI THanks for the info. The well head pressure is 75-55 pounds per square inch. That is high for a home well around the great lakes..they are usually set to 40:60 on:off. THe 150GPD RO unit is indicated to need 65lbs pressure though my reef guy/dealer says that everyone is running them at 40:60 anyway. I do I just jack my pressure switch up a bit to get more pressure.The well pump ( a submersible) is rated at 100lbs/.

I will replace the prefilters as there is iron in the water that escapes the iron remover that is ahead of the RO system and it has stained the prefilter particulate block red. Also, the iron remover machine is persnickety and is always malfunctioning and needing attention from Culligan the softener people. When it malfunctions it, of course, dumps iron into the downstream into the house. I also will check the pressures as I have just ordered an inline pressure meter which looks as if it would work perfectly for that job. A blocked prefilter could be it.
There is no throttle valve. I just open a designated Fawcett on full. THe waste restrictor is in place in the correct spot. There is a bypass/wash valve assembly on the RO unit and I do use it. By the way,there is a second RO unit ( 100gpd),fed by the same Fawcett and often both are going. THis one ,with a membrane replaced the same date as I got the 150 GPD one, remains working fine . It's prefilters are just as stained as the malfunctioning one.

A related point: I have heard it stated that activated carbon "bothers" discus. THe iron remover unit is nothing more than a gigantic cylinder of pressurized activated carbon..so everything in the house is precarbon filtered. If it does bother them, then my discus and altums are subjected to an industrial carbon filtration/adsorption, followed by the carbon block as it goes into the RO, then it is ROed then it is remineralised with calcium chloride and magnesium chloride and I add Kent trace elements. I have always wondered if it bothered the discus after all of that as sometimes they "sulk". THe altums seem totally at ease and ,on a day to day basis, seem more tolerant than the discus.
I do need to make make about 100 gallons of RO water a day to keep up so these RO units are working. Remineralizing the water from a different starting point each time (depending on the previous use,) is a bit of an art form and mistakes are made over time though I have gotten pretty good at it.
Al


Hi Al, I hadn't read your post before making mine, please accept my apologies.

You might look into investing in one of these semi commercial options, specifically the Hydrologic Evolution. They are on the expensive side when compares to most "point of use" RO units, as are all residential drinking water units as well as those marketed for aquarium use, but they are highly cost effective.

Your main concern is the cost of the two membranes when they need replacement. But take into account that depending on your tap water source the membrane useful life (for these units) can be extended for over 5 years with correct prefiltration, and this would include, ion-exchange resins as prefilters. Though my exprience is from my GE Merlin, which I ran on it's original membranes for 5 years, the Evolution is basically the same product, with a renovated and improved manifold design and increased production rated membranes.

One last thing that I like about these Evolution and Merlin Units is that they don't strip the water to the publicized 0.5 to 2% of the smaller units, from where users expect to see 0-5ppm TDS. Evolution and Merlin users will receive an additional benefit for their fish, that is, more minerals in their product water. These units skim out 90-92% of the bad stuff and you end up at around 8-10% of ppm of your tap water source. So if you have, i.e. 300ppm tap water, you'll be seeing close to 30ppm out of your RO. So for altums and discus, remineralization will be minimal. None needed for breeding, as 30ppm is close to optimal.

Ed

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God listens. He may not always give you everything you want, when you want it; but he always gives you what you really need, when you need it most!
E.R.


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