View Full Version : back flushing RO/DI
Ronny#66
09/20/2007, 08:13 PM
Pain in rear to switch red and blue lines can't realy get at fittings behind membrane aginst wall. Can you install ball valves so you can easily switch valved and back flusk without reducing flow when makeing water ? Also i only make six or so gallons of water weekly do I still need to change filters in six months /
kau_cinta_ku
09/20/2007, 08:21 PM
why are you switching lines around? don't you have a flush valve on your system?
kau_cinta_ku
09/20/2007, 08:23 PM
also yes the carbon and sediment filters should be changed no matter what every 6 monthes to help prolong the membraine the DI only needs to be changed when TDS readings start to raise.
AZDesertRat
09/20/2007, 08:24 PM
How are you backflushing the unit? Switching lines is not necessary at all, you do not want to run water backwards through the unit if that is what you are attempting. If flushing the membrane is what you are trying to achieve you install a flush valve which bypasses the flow restrictor and increases the flow to waste which in turn carries more flow past the EXTERIOR of the membrane carrying away and accumulated gunk.
A flush valve can easily be installed on the waste line.
<a href=showthread.php?s=&postid=10810022#post10810022 target=_blank>Originally posted</a> by Ronny#66
Also i only make six or so gallons of water weekly do I still need to change filters in six months
I just picked up a DI unit so I can't tell you about that. But as for the RO unit, no. When the clear cartridge looks visibly dirty it's time to replace your RO cartridges. I was getting a TDS of 11 after two years with my unit and haven't yet had to replace the membrane (which I'm dreading as they aren't cheap) The DI gives me a TDS of 0. You can get a TDS meter very cheap on eBay to give you an indicator as to when you need to change your membrane or DI cartridge. The TDS is all I really care about -- maybe someone can set me straight if there is anything else to be concerned about.
AZDesertRat
09/20/2007, 08:34 PM
Absolutely yes, change the filters every 6 months like clockwork. You can look back at any of my hundreds of posts on the reasons why but it can be a matter of human health. Slime bactreia and viruses can grow in the housings if they are not changed and housings disinfected on a regular basis. Don't let anyone tell you any different.
<a href=showthread.php?s=&postid=10810191#post10810191 target=_blank>Originally posted</a> by AZDesertRat
Absolutely yes, change the filters every 6 months like clockwork. You can look back at any of my hundreds of posts on the reasons why but it can be a matter of human health. Slime bactreia and viruses can grow in the housings if they are not changed and housings disinfected on a regular basis. Don't let anyone tell you any different.
I had no idea. I don't use mine for anything except the tank, so I don't drink it. Can I still get sick? Wouldn't bacteria and viriuses effect the TDS reading?
AZDesertRat
09/20/2007, 08:42 PM
A TDS meter may not show anything as its on the raw water side. I wish I had kept pictures of contaminated membranes I took when I worked for a large municipal water system, its really convincing. Not keeping up with filter changes can also shorten the life of or destroy a membrane in short order. Lots of factory installed carbon filters are only effective for less than 1,000 total gallons of normally chlorinated water. Thats 200 good gallons and 800 waste gallons through the unit! People don't think about the fact the waste goes through the filters too.
Yikes! Well, Ronny, disregard the crud I originally posted.
Now you got me concerned AZDesertRat -- time to ditch my entire pinnacle RO unit maybe and get a new one after two years of sitting in the garage except for the occasional FW change, and now I'm using it for my SW tank with the new DI unit..
Ronny#66
09/20/2007, 09:10 PM
You asked why i was switching lines on filter . Directions say I should switch wast red line and blue line on membrane . It didn't come with flush valve. and yes this is what i want to do.
AZDesertRat
09/20/2007, 09:15 PM
Who ever sold the unit does not know what they are doing then. I would talk to some more knowledgable people if it were me. I have never seen those instructions before and would love to know what brand it is so I can avoid it.
Ronny#66
09/21/2007, 08:15 PM
The brand is Coralife pure flo II And no flush valve and i read directions again and it says to switch the red and blue on membrane. It even sugests teflone tape for fittings.
AZDesertRat
09/21/2007, 08:49 PM
Doesn't surprise me, that is one of the worst units available I am sorry to say. The quality is really poor and if you look here on RC you will not see many good comments on them.
Ronny#66
09/21/2007, 09:04 PM
How do you find comments on this filter ?
Ronny#66
09/21/2007, 09:05 PM
Budget dictated what filter to buy !!
AZDesertRat
09/21/2007, 09:09 PM
Try the search button at the top of the page if it is working. Unfortunately we buy things without doing research, myself included sometimes. It is better to research and save up while you buy water somewhere than to buy a unit that will end up costing more in upgrades than what a good one would have cost to begin with. I've been there too!
With RO/DI you really do get what you pay for so expect to spend right at $150-$160 for a good high quality system that will live up to its claims and last for awhile.
Ronny#66
09/21/2007, 09:11 PM
That darned search is never working. By the way had my RO/DI tested and 0 everything.
Ronny#66
09/21/2007, 09:14 PM
I paid 150 bucks for that RO/DI DR. Foster & Smith.
AZDesertRat
09/21/2007, 09:18 PM
You don't even have a TDS meter? Shame on you. Thats the only reliable way to test RO/DI water, there are not enough ions to test with most anything else except a conductivity or resistivity meter. Get a TDS meter and use it every time you make water. You will find with a little testing the membrane is very probably not giving you 98% rejection and the DI will probably have a very short lifespan. Thats been the general consensus here anyway ans seems to be the norm for most low cost units from China and Taiwan like that one. They are mass produced by the thousands using low quality components unlike the units you find here on RC that are assembled one at a time in local shops by reef hobbysists themselves using high quality components. There really is a difference.
Ronny#66
09/21/2007, 09:21 PM
Ya I know Got to get a TDS I like foster and smith is that a good one?
Ronny#66
09/21/2007, 09:23 PM
i only got a 25 gal now have everything to set up a 75 just got to get the live rack and sand . I'm going to use the vender out od florida . Never heard anything negative about Richard.
AZDesertRat -- (And this is a serious question) Is my Pinnacle RO unit a P.O.S.? How about the Pure-Flo II Add-On Deionization Canister I added? Right now I'm getting 0 TDS.. I still haven't changed the membrane on the RO unit, but I'm just wondering after all you mentioned about bacteria/viruses... is this something I totally screwed up on buying and just ditch it all, or not? If so, what RO/DI unit (mfgr/model) would you recommend?
AZDesertRat
09/21/2007, 09:27 PM
Look at the 75 GPD premium system at www.buckeyefieldsupply.com for $161. It includes a Dow Filmtec RO membrane, pressure gauge, TDS meter, refillable 20 oz vertical DI with nuclear grade resin, flush valve and an adjustable flow restrictor. Much better true reef quality unit.
Or the Ocean Wave+ for $160 or better yet the Ocean Reef +1 for $199 at www.thefilterguys.biz .
Or the Optima Vision for $149, Optima Automated for $175 or the Optima Professional fro $199.
All are much superior units and include things like 75 GPD Dow Filmtec RO membranes and full size vertical 20 oz refillable DI filters. Most include TDS meters and pressure gauges. All use low micron rated siolid carbon blocks, no granular activated carbon and good quality prefilters with a low micron rating. Note with the one you have they don't even tell you who makes the membrane, what micron ratings some filters are and it does not have a pressure gauge or TDS meter. If you add all these things to that one you will have much more money invested.
So, that would be a yes, my RO/DI system is a P.O.S.? :)
AZDesertRat
09/21/2007, 09:34 PM
If you want a good TDS meter get the HM Digital COM-100, its the most sensitive and most accurate hobbyist grade meter on the market.
The Seachem is no better than the Coralife. Read the literature and look at all the gaps, do they tell you what filters are inside it? If not you can bet they are knock offs of low quality.
I listed several choice in the same price range above. Add www.melevsreef.com and www.spectrapure.com to the list of good units too.
Companies like Coralife and Seachem need to stick to making additives, lights and stuff and stay out of water treatment, they give it a bad name with their imported junk. Look at all the bad publicity in the news right now about Chinese manufacturers cutting corners when it comes to quality. Unfortunately its a reputation they earned all by themselves and its extends to units like these too.
Thank you :) Last question if you don't mind -- would you recommend keeping my current unit until the TDS starts reading above zero before purchasing, or is there any danger in using my current unit (I'm just using the raw water for the reef) that would necessitate an immediate upgrade to one of the fine RODI units you've listed?
aquarius77
09/22/2007, 02:14 AM
You will love yourself once you replace that unit. Until the one your running needs something that costs, i would keep running it.
The Filter guys rock!
AZDesertRat
09/22/2007, 11:04 AM
Use what you have. Since you already have it you might look at the price of a full replacement kit vs a new unit. You are looking at $160- $199 for a new unit and replacements will be signifcantly less than that. If you look at the cost of the old unit plus the replacements you will have more invested but it will be less than the cost of two units, the old and new.
I really try to catch people when they are first shopping so they don't buy the wrong units to begin with and end up spending more to get them working right.
The manual the Pinnacle provides tells me I should replace the membrane when it starts reading above 30 TDS -- With the new SW tank I'll be using it a lot more so I imagine it won't be long until I hit that mark -- the new Membrane as over $100, so I figure I'll just get a new unit when that time comes.
AZDesertRat
09/22/2007, 11:50 AM
A 75 GPD Dow Filmtec membrane should cost you about $45 most places. It is the standard of the industry and the choice of most vendors here on RC. An individually hand tested and guaranteed 98+% Spectrapure 90 GPD membrane is only $99 retail but you can probably beat that a little bit and its the cadillac of the industry.
How can they say "over 30 TDS" when they have no idea what your tap water TDS is to begin with? Companies like that really crack me up if it wasn't so sad. What it should say is when you begin to see anything less than 90-95% or so rejection rate you need to be shopping for a new membrane. It all depends on your water quality and how much you make.
Just picking your brain here :)
By a 90% rejection rate, you mean that, for example; if my tap measured at 500 TDS, then I would need a new membrane when the raw/clean water starts reading around 25? And the people getting 900 TDS would be shopping when they're reading 45? I assume this is all before the DI unit though, so in that case it would be OK to be sending water with a TDS of 25+ to the DI stage, and still expect ~0 TDS after DI?
AZDesertRat
09/22/2007, 12:41 PM
You are correct. The problem with letting it go too far is higher RO only TDS eats up DI resin in a hurry. My experience has been a 20 oz DI cartridge treats about 3000 total TDS, so if you are putting 25 into it you can expect to get only about 120 gallons of DI water per cartridge. This gets expensive in a hurry.
The better choice is get a good efficient RO membrane like I finally did. I bought he Spectrapure MaxCap system because my water is so hard and high in TDS. It averages 835 TDS.
With my old system which started out life as a Watts Premier drinking water system from Costco, which I heavily modified by the way with a 75 GPD Dow Filmtec RO membrane, high quality prefilter and carbon blocks, an add on vertical refillable DI canister and cartridge, TDS meter, pressure gauge, RO bypass valve etc., I was getting a RO only TDS of 13-15. DI cartridges lasted me almost exactly 150 gallons every time for years.
Now with my MaxCap and its Select series hand tested membrane I am getting a RO only TDS of between 5.2 and 6.4 using good COM-100 meter for testing. The DI even if I were using normal nuclear grade resin would last me 2 to 3 times longer. With the proprietary resins they use in the MaxCap and SilicaBuster cartridges though I got 630 gallons out of my first MaxCap cartridge (and I change DI when I first start to see any sign of TDS, they recommend letting it get to 1/3 to 1/2 of the incoming RO only TDS). I am at about that point on my replacement MaxCap cartridge now and will probably be changing it soon. Thats about 1300 gallons out of tw cartridges where I would have gone through about 10 with my old system. Because of that I will probably change my Select membrane when I see a RO only TDS of about 10-12 which is still better than a normal membrane.
As a point of interest I happened to see www.azseabottom.com has MaxCap systems on sale right now for $290 which is a significant savings off retail.
Awesome! Thank you for the very detailed reply. I've bookmarked both this thread and the MaxCap system link -- I think I'll purchase that MaxCap as soon as either my DI starts to go or my RO membrane goes -- explaining the new system to my wife (who bought the RO unit as a gift when I was starting FW planted tanks) will be a bit tricky but I'm sure I can come up with something :) Again, thank you very much, AZDesertRat! Very informative :)
Mavrk
09/22/2007, 08:48 PM
<a href=showthread.php?s=&postid=10818938#post10818938 target=_blank>Originally posted</a> by aquarius77
The Filter guys rock!
I second that!
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