Ebay RO/DI Units...

[BeanAnimal]

<a href=showthread.php?s=&postid=9744958#post9744958 target=_blank>Originally posted</a> by bstreep
If I can ignore all of the bickering...

I have both a Coralife unit, and an Aquasafe unit. There's no contest. The Aquasafe unit is far superior, it's worked without a hitch for 2 years (with regular filter changes...). The Coralife unit is, IMO, junk.

Not much by Coralife has impressed me... your observations are likely valid at least from my perspective. I do not know much about the coralife unit... and frankly do not want to take the time to look up the specs as you are not the first person to convey that sentiment about it.

 

[twkenny]

Actually, like I stated....I elected to change the horizontal bed because it was a pain to change. I got the membrane free from a vendor who got it back on return and it was opened.
Agian though, in my opinion, the cheaper ebay units are not the best way to go. This coming from my experience with them.

 

[kau_cinta_ku]

<a href=showthread.php?s=&postid=9744581#post9744581 target=_blank>Originally posted</a> by Texas Reef
I am going with a Purely Optima Vision with flush kit and tds meter.

Seems to be what I want at not a really expensive price.

Once again, thanks for all the info. This thread has over all been informative.

great product IMO i first started out with a filter direct unit that i got from ebay for 120 shipped. worked well for about 5 monthes then no matter what i did i couldn't get my tds down to 0 again so now i own the purelyh2o optima pro unit and have loved it ever sence. the filter direct unit is still good for drinking water though just won't go near my tank.

 

[Colin]

Somebody asked for specs on an Ebay unit, here they are. Aqua Safe unit, 177 in, 12 out with the stock membrane. That's about 93% with the stock 100 GPD membrane, made out of Dow materials by Applied Membranes. Yes, this Ebay vendor does specify thier vendor.

Now some plain talk and common sense. I'm going to address Aqua Safe, simply because I have experience with them. The unit is solidly constructed, with quick connect fittings. The membrane is better than average for a 100GPD. The DI stage is 16 oz of Purolite resin (yes, it's horizontal, and yes, they specify their manufacturer). It has a 5 micron sediment, GAC, and 5 micron carbon block (3 stage prefilter). I've e-mailed with questions and received answers. Customer service is there. Price: $70. Is it a good value? Absolutely. Even with a $45 membrane upgrade to a Dow 75 it's a good value.

Now, let's look at the RC Vendors. I'm not going to consider SpectraPure since they're priced significantly higher than the units that are being discussed here. I know Rat really likes them, and I would too if I had his source water. They're probably well worth the money if you have high TDS like he does.

In looking at the RC vendors, I see one that has a small, horizontal DI cartridge. Some offer 100 GPD membranes. I see several that only have 2 prefilter stages of various micron ratings. I see in the vendor forums that all have at least some problems and customer service issues.

What's my point? My point is that Ebay units can be good, and RC vendor units are not all the "Second Coming". There is a wide range of quality, prices, service, and features across all of these companies. In the end, it's like anything else in this hobby. You need to research the purchase beforehand and make an informed decision or you may end up paying way too much or not getting what you need/want.

One final thought on resin life. It really doesn't matter to me whether I'm changing resin once a year or once every two years. At $10 a for a full refill, I could care less.

Now, back to the regularly scheduled flaming.

--Colin

 

[twkenny]

Now that was a good post!!!!!

You hit that nail on the head Colin.

 

[Reefugee]

Colin,

I wonder if I just got lucky. I have the AquaSafe unit as well. My tap water reads 546 ppm, RO 2, post DI 0. That's a 99.6% with the stock 100GPD RO membrane. I did replace my pre-filters with AWI's filter (10 micron sediment, 5 micron carbon, and 1 micron carbon).

Just out of curiosity - when you replace the RO membrane from a 100GPD to 75GPD, don't you have to purchase a new flow restrictor as well?

Minh

<a href=showthread.php?s=&postid=9746741#post9746741 target=_blank>Originally posted</a> by Colin
Somebody asked for specs on an Ebay unit, here they are. Aqua Safe unit, 177 in, 12 out with the stock membrane. That's about 93% with the stock 100 GPD membrane, made out of Dow materials by Applied Membranes. Yes, this Ebay vendor does specify thier vendor.

 

[BeanAnimal]

Yes, you got VERY lucky Not only does your membrane do much better than average, it does MUCH better than the rated spec.

Yes, you should replace the flow restrictor to adjust the waste to product ratio back down to around 4:1.

 

[rubikcube]

Here are my numbers:

Tap: 650ppm
Tap Temp: 61 degrees F
Tap Pressure: 50 psi
After RO: 13ppm
After DI: 0ppm

This is the eBay water general RD-106 unit. It came with a 100 GPD GE Desal membrane and the horizontal DI. It also came with an RO storage tank and faucet. All this for $109. I added on a dual inline TDS meter for $32. Shipping was $30. Total of $171.

When I received the unit, I was getting poor rejection probably due to the 100 GPD membrane. I called up their tech support to ask what was up. A few days later I had a brand new 75 GPD Desal membrane in a brand new housing. After all this it works great.

I get 98% rejection on my membrane. Dow doesn't guarantee better than 96% on their membranes.

My DI water reads 0ppm on my dual inline TDS meter. I understand that there is a big difference between 0ppm and 18.2 megaohm resistivity. However, I am not alone in saying that a 0-1ppm reading on a regular TDS meter is fine for our uses. If someday I decide to open up a silcon chip fabrication facility in my house, then I'll start worrying about it. Until then, anything over nuclear grade is just plain overkill.

My DI is the refillable horizontal kind. It may not be as good as the vertical kind, but I continue to get 0ppm readings. No one can explain why less than 0 is better for reefkeeping. Horizontal units do not cause elevated TDS contrary to the above opinion.

AZDesertRat, I realize that you are an expert, but promoting the oversimplified 2% rule is just plain wrong. Your rule only works going from 96 to 98%. Any other time, it's mathematically incorrect. Also, while we are in the business of sharing numbers, why don't you share the cost of your unit along with what membrane you use?

Everyone always talks about how the prefilters and resin is junk, but I just don't buy it. My prefilters look exactly like the ones on thefilterguys website. As for the resin, I haven't seen anyone give a NUMBER on the capacity of their DI resin. Actually thefilterguys are the only ones to even attempt to give a good explanation as to why some people might need different prefilters than others.

 

[twkenny]

My feeling about the horizontal bed is that it's sort of a pain to deal with. The larger, vertical chamber is a lot easier and quicker to service, plus is has to be done less often. Also, the horizontal beds were prone so settling and allowing water to follow the path of least resistance and come out above zero TDS. I never experinced this until I refilled the canisters myself. As hard as I tried, I could not get the resin to pack as tightly as the factory did.
I just got tired of messing with mine....plus they always wanted to leak a bit. Nothing some Teflon tape didn't cure, but the o-ringed standard housing is just easier to me.
I think the argument for the "better" units is long term cost. You and I got lucky because we got free 75 GPD membranes. A lot of folks are using more resin with their 100GPD membranes. If you upgrade the membrane, you're close to what a unit from AWI or Purely H20 costs...plus you get the vertical DI.

 

[BeanAnimal]

I get 98% rejection on my membrane. Dow doesn't guarantee better than 96% on their membranes.

You speak as if GE DESAL does... they do not either So all that means is that YOU got a membrane that exceeds the average specs.

With regards to the refillable horizontal DI. YOU may not have a problem, but a majority of users DO. The simple fact is that they are not effective at using ALL of the RESIN. Simply physics dictates this. So yes, some folks have good luck with well packed horizontal units, but they design flaws are still there and rear their ugly heads more often than not.

Why exactly does the math only work from 96% to 98%? Do you care to show us what the difference in DI usage between a 96% and and 93% membranes output would be? What about 92% and 96%? Last I checked, percentages were linear and easily applied to ANY quantity. I think you need to check your math

What can you tell by "looking" at a prefilter on a website? What do you know about the different types of carbon blocks?

As for resin capacity, there are many different grades. Several people have shown that the DI resin that comes with many of the discount units, is discount resin. How is it shipped, stored and handled prior to use? If you call any of the reputable vendors they will give you resin capacities and details (more than you wanted to know).

There is a HUGE market for "knock off" goods. Things like plastic and resin are prime markets for such goods. When a price is too good ot be true, it is for a reason. I am not sure why people have such a hard time grasping that...

Lets do this. Can somebody get their eBay vendor to provide the name brand and data sheet for the resin they use. We can go from there.

Just something to think about:
One company pays to advertise and prides themselves in personal customer service and honesty with very few complaints. Another company uses deceptive marketing techniques to peddle their wares and has an appriciable number of pulbic complaints. Which company do you think uses better raw materials? Yes, it is still a guess... the educated guess be right most of the time.

In previous threads, we have picked apart several "eBay" adds and shown how dishonest or deceptive they are. Should you trust a company that uses deception and outright lies to peddle their wares? If they are dishonest from the getgo, what else are they being dishonest about?

 

[BeanAnimal]

think the argument for the "better" units is long term cost. You and I got lucky because we got free 75 GPD membranes. A lot of folks are using more resin with their 100GPD membranes.

That has been the MAJOR point from ALL of "US" all along.

Again, with your low (65) TDS... you were in a different "cost" position that most to begin with.

 

[Colin]

<a href=showthread.php?s=&postid=9747591#post9747591 target=_blank>Originally posted</a> by Reefugee
Colin,

I wonder if I just got lucky. I have the AquaSafe unit as well. My tap water reads 546 ppm, RO 2, post DI 0. That's a 99.6% with the stock 100GPD RO membrane. I did replace my pre-filters with AWI's filter (10 micron sediment, 5 micron carbon, and 1 micron carbon).

Just out of curiosity - when you replace the RO membrane from a 100GPD to 75GPD, don't you have to purchase a new flow restrictor as well?

Minh

Yep, you need to replace the flow restrictor. I suggest an adjustable one. Buckeye sells them. That way, you can adjust it for seasonal water temperature variations.

--Colin

 

[BeanAnimal]

Yes adjustable is nice... I have not tried one yet, but it has been on the list for a while. My winter water temps put my waste ration through the roof and I evap at least 5 gallons a day.

 

[AZDesertRat]

The 2% efficiency rule works always. It may not be an exact science but it has been proven time and again that anytime you improve roughly 2% you double the DI life from what it was previously. That can be an improvement from 90% to 92% or 96% to 98% or wherever.

My RO membrane is a hand tested SpectraSelect 90 GPD membrane rated at 98+% rejection guaranteed.

If you get an adjustable flow restrictor make sure it can be locked in position, its easy to bump it and throw the settings out of whack. I prefer having two capillary type restrictors cut to length for different seasonal water temperatures. Here in Phoenix I don't have to worry about it because believe it or not our tap water is colder in the summer months than in the winter. The intakes to the canal delivery system draw from lower levels in the reservoirs in the summer so the temps are in the mid 50s to the low 60s year round in my area.

 

[RobbyG]

<a href=showthread.php?s=&postid=9743276#post9743276 target=_blank>Originally posted</a> by Reefugee
I don't claim my unit to be the "best" unit out there. But over the past two years, it has served me well. I thought I'd share what I posted in my local club forum. I wish I had run the following test with the pre-filters that came with my AquaSafe RODI system. I bought my system 2 years ago - so it's possible that the quality of the unit might have changed.

Something must be wrong with your numbers, I don't think it's possible for an RO membrane to take the water from 546ppm down to 2ppm. That Rejection rate exceeds any figures I have ever seen. I suspect your meter is inaccurate which would mean all your conclusions are inaccurate.

 

[rubikcube]

<a href=showthread.php?s=&postid=9747869#post9747869 target=_blank>Originally posted</a> by BeanAnimal
You speak as if GE DESAL does... they do not either So all that means is that YOU got a membrane that exceeds the average specs.

My point is that the rejection rate is a crapshoot unless you get the specraselect membranes that are actually verified.

With regards to the refillable horizontal DI. YOU may not have a problem, but a majority of users DO. The simple fact is that they are not effective at using ALL of the RESIN. Simply physics dictates this. So yes, some folks have good luck with well packed horizontal units, but they design flaws are still there and rear their ugly heads more often than not.

How hard is it to turn the DI vertical if you have this problem?

Why exactly does the math only work from 96% to 98%? Do you care to show us what the difference in DI usage between a 96% and and 93% membranes output would be? What about 92% and 96%? Last I checked, percentages were linear and easily applied to ANY quantity. I think you need to check your math

I can't believe I'm actually having to explain this.

Let's take my Tap numbers at 650 ppm. Here is a quick table of rejections and resulting TDS readings. I've also included how many gallons of the resulting RO water can be processed by a cartridge with a capacity of 5000ppm TDS(just a number I pulled out of nowhere).

90%=65ppm yields 76.92 gal
92%=52ppm yields 96.15 gal
93%=45.5ppm yields 109.89 gal
94%=39ppm yields 128.2 gal
96%=26ppm yields 192.3 gal
98%=13ppm yields 384.61 gal
99%=6.5ppm yields 769.23 gal
100%=0ppm yields virtually unlimited gallons

The statement was that for every 2% increase in rejection, you will double the capacity of your resin. You can see this does in fact work form 96-98% since 192.3 is half of 384.61. However, let's look at the 90-92% increase. 76.92 is certainly not half of 96.15. How about 92-94%? Wrong again. What about 98-99%. The DI resin life doubles, but for only a 1% increase in rejection. For your numbers of 93-96% resin life increases by a factor of 1.74. For 92-96% resin life doubles but for a rejection increase of 4%.

What can you tell by "looking" at a prefilter on a website? What do you know about the different types of carbon blocks?

I can tell you from looking at their website that the blocks were at least the same brand. All I know about carbon blocks is what thefilterguys put on their site.

As for resin capacity, there are many different grades. Several people have shown that the DI resin that comes with many of the discount units, is discount resin. How is it shipped, stored and handled prior to use? If you call any of the reputable vendors they will give you resin capacities and details (more than you wanted to know).

Many different grades but no capacity numbers. Capacity is what counts when it comes to doing a cost analysis. If they'll tell you over the phone, why not on the website? A quick check shows that neither spectrapure or thefilterguys shows resin capacities on their site. Neither of them show how it was shipped, stored or handled.

There is a HUGE market for "knock off" goods. Things like plastic and resin are prime markets for such goods. When a price is too good ot be true, it is for a reason. I am not sure why people have such a hard time grasping that...

The truth is that you and I have no clue what the quality of the plastic is on any of the units in question. What types and grades of plastic does spectrapure use on their units?

Lets do this. Can somebody get their eBay vendor to provide the name brand and data sheet for the resin they use. We can go from there.

A quick search shows that one of the units uses Purolite. I would be willing to bet that mine uses Purolite as well(though they don't state that) since it is the cheapest option available on a bulk resin purchasing site.

Just something to think about:
One company pays to advertise and prides themselves in personal customer service and honesty with very few complaints. Another company uses deceptive marketing techniques to peddle their wares and has an appriciable number of pulbic complaints. Which company do you think uses better raw materials? Yes, it is still a guess... the educated guess be right most of the time.

The only info you base your educated guess on is how much it costs. Not much of a guess.

In previous threads, we have picked apart several "eBay" adds and shown how dishonest or deceptive they are. Should you trust a company that uses deception and outright lies to peddle their wares? If they are dishonest from the getgo, what else are they being dishonest about?

I won't comment on their honesty, but I will say that if you do the research that you should be doing before buying one of these things, you should be able to pick out most of the false statements.

 

[lovefish2]

Hey so where is the best place(and somewhat inexpensive) to buy a good RO/DI unit..

 

[RobbyG]

BeanAnimal and AZ you guys deserve a medal, the utter crap you guys put up with while trying to help your fellow RC member is just amazing. I stopped getting into these Ro threads a long time ago, it's just too difficult to separate out the people who work for Ebay companies versus those who are just passionate and uninformed.

 

[AZDesertRat]

Right here on RC.
www.buckeyefieldsupply.com
www.thefilterguys.biz
www.spectrapure.com
www.purelyh2o.com
www.melevsreef.com

 

[RobbyG]

Guys listen to AZ and Bean. They are two out of the three leading Ro water experts on RC and they don't work for any of these companies, what they are telling you is the truth and they put up with the BS posts because they are passionate about this subject and are trying to save you from long term expenses and headaches.

Ebay units are not in the same league as the one's mentioned by AZ. I purchased one of the Dvoneb units and it is now sitting in my closet after months of problems. I recommend you spend a few extra dollars and get a good unit.