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Unread 11/04/2007, 03:48 PM   #1
chucksta1
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Phosphate level in R/O

A two part question...


What should the level be, or, what is an acceptable level of phosphate in the output of a R/O water maker? Is it supposed to be 0?

That being said, if the TDS reading of the output is 004 ( 160 going in ), does that indicate where the problem is? As in, is it the membrane or the charcoal insert?


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Unread 11/04/2007, 03:57 PM   #2
virginiadiver69
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4 ppm in your ro water is fine. you'll need to add the DI stage to get down to zero though. That could be your reason for phosphate also. When you do add the DI stage stay with a full size canister, not a horizontal one.


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Unread 11/04/2007, 04:30 PM   #3
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The LFS was unsure what if any components should be replaced in the R/O unit. I asked how could the mambrane be shot and still show 004 on the output. That got a blank look. I asked if it was the job of the charcoal to remove phosphate. That got another blank look. All he knew was that the phosphate out should be zero, but couldn't tell me what had failed to allow phosphate to come through.


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Unread 11/04/2007, 10:13 PM   #4
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Or should I have put this in the equipment forum??


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Unread 11/04/2007, 10:38 PM   #5
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The filters will get used up after a while and need to be replaced.
I like to see 0 ppm on the TDS reading but as the filters get worn that will gradually increase. I would probably replace it around 5 or 10 ppm. The DI resin will most likely have to be replaced more often then the others.
Your best bet is to test when the filters are new and see how low that your filtration system will bring you levels and compare that to a tap water test.
Then you can monitor your water treatment system over time and you will be able to get a feel for how long your filters will last and how often your going to need to replace them.

I wouldn't bother asking the LFS about water treatment equipment. They're most likely not going to be prepared to answer you questions and even if they do, their answers will be questionable to say the least.

As far as an acceptable level of Phosphate, I can not answer your question as I'm not a chemical engineer. I would consider a nice Google search or this site has a forum that would most likely be a good place to start.
Check out:
http://www.reefcentral.com/forums/fo...s=&forumid=112


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Unread 11/05/2007, 12:06 AM   #6
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Starting to get the idea.. This might take some more investigating. I never thought to check the tap water to see what thee phosphate reading was from the source, and what, if any, drop there was after the R/O unit. I don't have D/I , just R/0. From what I've been able to find here on RC., the R/O unit should take the TDS down about 90% to 95%. I'm getting that out of it, but what I can't find the answer to, is if the unit is supposed to drop the phosphates to 0 or not. If it's not, then the problem is accumulated phosphates. If it is supposed to remove phosphates, then what has failed? Is the membrane shot even though the TDS is below 005? Does a D/I/ unit take out phosphate?


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Unread 11/05/2007, 01:03 AM   #7
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It looks like the RO membrane filters out 90 to 98% and then the DI resin will pick up additional Phosphate to get it within the acceptable levels. It really depends on the how much phosphate is in the tap water to begin with. Ideally you wish to maintain your phosphate concentration at 0.03 to 0.04 ppm according to an article i was reading earlier. I did a Google seach and found information readily available. You should try it out


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Unread 11/06/2007, 03:32 PM   #8
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So, if the membrane is showing 004 TDS, but I've got phosphate in the out put, it's shot and should be replaced. If that's the case, I got about three thousand gallons out of it before it died. (2 1/2 years at three gallons a day.)


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Unread 11/06/2007, 04:08 PM   #9
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OK, from the beginning.

Phosphates should be almost undetectable but with RO only you may never see 0 phosphates if you have any amount to begin with. Phosphates are a tough thing to remove and require the combination of RO and a good DI to get to a true 0.

The TDS level from an RO only unit should be 95-98% less than what the tap water TDS was to begin with. Obviously the lower the final TDS the better, so stick with name brand RO membranes like a Dow Filmtec 75 GPD or maybe Applied Membranes or GE Water(Osmonics). There are no name Chinese knock offs on the market that do not carry ANSI/NSF ratings for sale and use in the USA for drinking water so pay attention to what you buy and always buy from a trusted source. Also stay away from the Dow 100 GPD membrane as it is NOT a reverse osmosis membrane but is a 90% efficient nano fiter ANSI/NSF rated for "Pool and Spa Use" and not drinking water which is much better.

A RO only TDS of 4, down from a tap water TDS of 160 is pretty good. You are getting a 96.25% rejection rate which is acceptable to most people. What you are referring to as "Charcoal" is actually activated carbon, yours may be granular activated carbon or it may be a solid carbon block which is much more efficient and has a much greater lifespan.

The poly prefilter and the carbons main duty are to protect the RO membrane with the prefilter removing suspended solids down to whatever its micron rating is (the smaller the better like less than 1.0) and the carbon removing chlorine. The carbon also does double duty by adsorbing volatile organic chemicals so it helps the membrane out. Important things to remember are, always replace the prefilter and carbon at 6 month intervals so you do not damage the membrane or pose the risk of bacteria or viruses growing inside the housings. Always disinfect the housings while you have the filters out, your vendor should have given you directions on how to do so and this is important! Next is always use a solid carbon block again in as low a micron rating as you can get, I prefer a 0.5 micron which is good for up to 20,000 gallons of normally chlorinated water. A cheap standard granular activated carbon cartridge can be exhausted in as little as 300 gallons, that's 300 gallons total through your RO system including the waste since it also goes through the carbon! That's like 60 gallons of good RO water and 240 gallons of waste with a normal 4:1 waste ratio. Not ver ygood at all when you think about it!

Now, the prefilter and carbon have very little to absolutely no effect on final TDS as I said they are there to protect the RO membrane which is what removes Total Dissolved Solids or TDS as we know it. If your TDS is rising then its the membrane that would need to be replaced but at 96+ % you are still in good shape with such low TDS to begin with. For me with a tap water TDS of 830 I would be looking for a new membrane at 96% because I would be getting an RO only TDS of 33 and be going through DI like crazy.

If you want to see 0 TDS which most of us do then you need a DI filter after your RO. Look for a full sized 10" vertical canister type with a refillable cartridge that holds 20 oz of resin for best treatment, best filter life and lowest replacement cost since you can buy bulk resin cheaper than throw away cartridges.

I will say Phosphates, Silicates and Nitrates are three of the harder things to remove as they are weakly ionized or electrically charged so even DI can have trouble. Two things you might consider, one is let the water travel through the DI resin bed very slowly so you have good contact time and the second is look into a DI cartridge designed specifically to work on phosphates and silicates like the SilicaBuster from www.spectrapure.com .

You water utility is probably feeding orthophosphates for corrosion control in the Cities distribution system.

To sum it up, use high quality replacement filters in low micron ratings, a solid carbon block again in a low micron rating, add a DI and stick to a regular replacement/maintenance schedule and you should have good reef quality water for a long time.


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Unread 11/07/2007, 06:20 AM   #10
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O.K., so if it's the DI's job to remove phosphates from the water, and a DI goes after the R/O, then I guess it would be safe to say that the R/O unit has not "failed" per se, but rather that there is now a lot more phosphates in the supply water than there was previously.

Three months ago, before this started, the city changed all the water pipes in the area. Kinda makes me wonder... Did they dick with the chemistry at the same time?

Looks like this IS a problem that money can fix. Time for new cartriges and a DI unit.

I bought a phosphate reactor on Ebay, so I hope that will cause a die off of the algae. Hopefully new cartriges and a DI will keep it away.

Thanks for the help!!


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Unread 11/07/2007, 08:54 AM   #11
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Keep a close eye on your DI final TDS. When DI nears exhaustion it starts to release weakly ionized contaminants back into the treated water. Phosphates, silicates and nitrates are three of the most weakly ionized substances. They can often be released in large quantities, much higher than the source water was to begin with. When I start to see anything other than 0 TDS I change my DI resin just to be safe, its cheap insurance.


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Unread 11/08/2007, 02:13 AM   #12
chucksta1
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I don't trust my LFS as far as I can throw them ( Not after selling me a prism skimmer), so E-bay it is! What do I type in the search box to find DI units and replacement bits for a CoralLife R/0 unit?

Search for DI didn't work, but I'm sure there on there.

If anyone has any brand recomendations to look for or to avoid, I'd appreciate it!!

Thanks!!


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Unread 11/08/2007, 08:46 AM   #13
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In general, stay away from e-bay for RO/DI units and supplies. There are exception but for the most part if you are shopping for price be warned, "You get what you pay for with RO/DI" and cheap is exactly that.
If you are looking for an add on DI, sponsors here on RC including www.thefilterguys.biz , www.buckeyefieldsupply.com and others have a complete add on kit including a standard sized 10" vertical canister, refillable cartridge with 20 oz of FRESH semiconductor or nuclear grade resin and the plumbing needed to hook it all up for about $40.

More often than not with e-bay you never know what you are going to get or if the vendor will be around tomorrow to stand behind it. Again there are exceptions but its rare.


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Unread 11/08/2007, 11:01 PM   #14
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Thanks for the links, I'll check it out.
When I bought the reactor on e-bay, it was because it was literally half the price of the LFS. and my LFS is the largest chain in Canada. And it wasn't a similar product, it was the identical brand. Delivered to my door for less. The Over the Counter selection in my area is pathetic and over priced. The only way to get quality name brand merchandise is e-bay or import. It's not about money, it's as much about choice and quality.

Thanks all for the help!

It's not a fish tank... it's a glass hole ya throws money in it ya does...


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