Ebay RO/DI Units...
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RobbyG
Active member
This is exactly what the self proclaimed experts are saying and you just proved their point. I have been running a Typhoon 3 for 18 months and I have not had to replace any filters or the membrane yet. The only thing I did was refill the DI resin about 4 months ago when the TDS crept up to 3ppm. On the other hand you are now buying all new filters, buying an new membrane and a new DI cartridge. Thats almost a whole new unit in just 18 months. Were have the saving gone to
RobbyG: So my post is BS because I point out their faulty logic? Get ready for some more.
So after searching on Spectrapure's website I found their capacity info on the MaxCap cartridges. So let's make up 3600 gallons of water assuming a final RO TDS of 20ppm and look at the numbers:
For the MaxCap system(with their so called 90 GPD membrane) to make that amount of water, you would need 3 MaxCap cartridges and one regular mixed bed cartridge. This method uses two vertical cartridges with the MaxCap being placed upstream of the regular. The total cost according to their site(without shipping) is $131. Assuming you refill that regular cartridge with resin from thefilterguys instead of buying it from Spectrapure, your cost will be $117. These prices do not include shipping.
Now, assuming we aren't using the MaxCap system, but have the same TDS coming into the DI. The same 3600 gallons would cost you $108 from thefilterguys.
The difference? Absolutely none. The water will be the same quality. However, the MaxCap system will cost you $350 dollars to start with.
So after searching on Spectrapure's website I found their capacity info on the MaxCap cartridges. So let's make up 3600 gallons of water assuming a final RO TDS of 20ppm and look at the numbers:
For the MaxCap system(with their so called 90 GPD membrane) to make that amount of water, you would need 3 MaxCap cartridges and one regular mixed bed cartridge. This method uses two vertical cartridges with the MaxCap being placed upstream of the regular. The total cost according to their site(without shipping) is $131. Assuming you refill that regular cartridge with resin from thefilterguys instead of buying it from Spectrapure, your cost will be $117. These prices do not include shipping.
Now, assuming we aren't using the MaxCap system, but have the same TDS coming into the DI. The same 3600 gallons would cost you $108 from thefilterguys.
The difference? Absolutely none. The water will be the same quality. However, the MaxCap system will cost you $350 dollars to start with.
twkenny
New member
<a href=showthread.php?s=&postid=9748659#post9748659 target=_blank>Originally posted</a> by RobbyG
This is exactly what the self proclaimed experts are saying and you just proved their point. I have been running a Typhoon 3 for 18 months and I have not had to replace any filters or the membrane yet. The only thing I did was refill the DI resin about 4 months ago when the TDS crept up to 3ppm. On the other hand you are now buying all new filters, buying an new membrane and a new DI cartridge. Thats almost a whole new unit in just 18 months. Were have the saving gone to
I thought you were supposed to change the filters and sanitize your housings after 6 months. ?
Texas Reef
Premium Member
I don't have any kind of knowledge on what makes an RO/DI unit good, but I have no problem spending an extra $50 for the peace of mind knowing that I bought from a reputable dealer.
I am not saying anything bad about the ebay units (I don't know enough about RO/DIs to make any kind of judgement), I just want to buy a well regarded product.
Water is not something I want to have to always worry about. There are people here that like the ebay units and others that swear by the "name brand" units. With so many varying opinions, I will spend a little more for peace of mind.
I am not saying anything bad about the ebay units (I don't know enough about RO/DIs to make any kind of judgement), I just want to buy a well regarded product.
Water is not something I want to have to always worry about. There are people here that like the ebay units and others that swear by the "name brand" units. With so many varying opinions, I will spend a little more for peace of mind.
Thats cool I have alot of friends that reside there.. So if you are not having any problem with your e-bay unit I think that is great. My friends that reside there state that the water quality there is not the best so if youre unit is working I think that should say something about the unit performance issues that were brought up..
RobbyG
Active member
I will ask BeanAnimal to answer this one, I don't profess to being a RO expert and I am not familiar with all the Brands etc. Aquarium controllers is my area, just like RO System are AZ's and Beans expertise.
Since I joined RC I have learned to trust the people who are experts in their area, they aren't selling anything and have nothing to gain they just do it because it's what they know the stuff and want to help fellow reefers.
What I do know about RO has been learned from reading posts by AZ and Bean and I also know a crappy piece of equipment when I use it, and nothing was more of a disappointing purchase than my old Ebay Ro system.
Since I joined RC I have learned to trust the people who are experts in their area, they aren't selling anything and have nothing to gain they just do it because it's what they know the stuff and want to help fellow reefers.
What I do know about RO has been learned from reading posts by AZ and Bean and I also know a crappy piece of equipment when I use it, and nothing was more of a disappointing purchase than my old Ebay Ro system.
I would recommend mine again as long as you ask the company to include a 75 GPD membrane instead of a 100 GPD membrane.
The only thing I wouldn't mind having is the vertical DI. Not because it performs better, but because it would involve less maintenance. I'll probably pick one up from thefilterguys whenever I buy replacement filters from them. It's only 36 bucks with fittings and a DI cartridge. I'll still come out spending a lot less.
The only thing I wouldn't mind having is the vertical DI. Not because it performs better, but because it would involve less maintenance. I'll probably pick one up from thefilterguys whenever I buy replacement filters from them. It's only 36 bucks with fittings and a DI cartridge. I'll still come out spending a lot less.
BeanAnimal
Premium Member
My point is that the rejection rate is a crapshoot unless you get the specraselect membranes that are actually verified. In a way yes. However the "average" specs are better for the DOW FILMTEC and therefore the chances of getting a better overall performance are also with the filmtec 
How hard is it to turn the DI vertical if you have this problem? turning a horzontal unit vertical and a vertical DI unit are two different things Turning the horizontal unit vertical can certainly help some.
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. I apologize. I did not read the entire context of what I replied to. You are correct when the numbers are looked at that way. I suspect our (my) perspective was that I was talking about 2% of the total volume. That is 2% of 650 is 13. For each 2% increment the TDS of the output is increased by 13ppm. Each 13ppm increase in output (ala 2% decrease in rejection) increments the DI usage by a factor of 2% (of the 650ppm)... Blah anyway no matter how we look at the numbers, the very obvious fact is that you NEED to be in the 96% or better rejection area to be cost effective, lower than that and you are bleeding money through DI costs.
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.There is a very real difference between bargain basement filters and carbon blocks. I know for a fact that some of the vendors do use very poor quality filters. I also know (from personal conversation) that the sponsors here all use high quality filters and blocks.
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. AWI puts the numbers on their site as well. Part of the problem is that they rate the resin in microsiemens, not PPM. Nobody said that they did show how it was shipped handled or stored. But again, after talking with these guys I can confirm that they treat the resin as it should be. A "quick search" will find plenty of links here and on various websites that show the very short lifespan of resin shipped by some of the 'eBay' vendors. This means 1 of 2 things. Either the resin was mishandled or stored, or the resin was low quality to begin with. It was just something to consider
The only info you base your educated guess on is how much it costs. Not much of a guess. And what would make you think that? I work with products and raw materials daily that are sourced from "overseas" companies. I have done a fair amount of sourcing on my own and also have a client that does billion dollar supply chain management for global companies. I have a fairly firm grasp on the topic. I can site dozens of examples of how this rings true (and sadly falls right in line with pricing, wholesale and sometimes retail). That is however another whole subject. I "quick search" will reveal that the cheaper housings are simply more prone to failure No great leap of faith 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. Still something to look into... but may certainly be worth the effort. AZRat can speak to resin brands and value better than I can. I understand the subject and the differences, but do not know the players.
Thanks for the kind reply.
How hard is it to turn the DI vertical if you have this problem? turning a horzontal unit vertical and a vertical DI unit are two different things
Turning the horizontal unit vertical can certainly help some.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. I apologize. I did not read the entire context of what I replied to. You are correct when the numbers are looked at that way. I suspect our (my) perspective was that I was talking about 2% of the total volume. That is 2% of 650 is 13. For each 2% increment the TDS of the output is increased by 13ppm. Each 13ppm increase in output (ala 2% decrease in rejection) increments the DI usage by a factor of 2% (of the 650ppm)... Blah anyway no matter how we look at the numbers, the very obvious fact is that you NEED to be in the 96% or better rejection area to be cost effective, lower than that and you are bleeding money through DI costs.
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.There is a very real difference between bargain basement filters and carbon blocks. I know for a fact that some of the vendors do use very poor quality filters. I also know (from personal conversation) that the sponsors here all use high quality filters and blocks.
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. AWI puts the numbers on their site as well. Part of the problem is that they rate the resin in microsiemens, not PPM. Nobody said that they did show how it was shipped handled or stored. But again, after talking with these guys I can confirm that they treat the resin as it should be. A "quick search" will find plenty of links here and on various websites that show the very short lifespan of resin shipped by some of the 'eBay' vendors. This means 1 of 2 things. Either the resin was mishandled or stored, or the resin was low quality to begin with. It was just something to consider
The only info you base your educated guess on is how much it costs. Not much of a guess. And what would make you think that? I work with products and raw materials daily that are sourced from "overseas" companies. I have done a fair amount of sourcing on my own and also have a client that does billion dollar supply chain management for global companies. I have a fairly firm grasp on the topic. I can site dozens of examples of how this rings true (and sadly falls right in line with pricing, wholesale and sometimes retail). That is however another whole subject. I "quick search" will reveal that the cheaper housings are simply more prone to failure
No great leap of faith 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. Still something to look into... but may certainly be worth the effort. AZRat can speak to resin brands and value better than I can. I understand the subject and the differences, but do not know the players.
Thanks for the kind reply.
BeanAnimal
Premium Member
Nah, not my area of expertise per say, just something that I understand (they are very simple devices with fairly finite operating parameters and predictable results).
You are correct, I have nothing to gain here and am certainly not selling anything. I just like to help people. I hate asking a questions and getting poor answers.
Colin
New member
I think dismissing all units sold on Ebay while promoting the units sold by sponsors is an injustice too. Obvously, some Ebay companies (like Aqua Safe) make a good quality, effective unit, and several of the sponsors sell some really low end stuff (like a carbon filter + a membrane).
We really should be talking about individual products here, and not about where they're sold.
--Colin
BeanAnimal
Premium Member
Lets look at just doing DI with no RO:
25 PPM into the max cap system will yeild 1800 GALLONS of water. That is $99 for the base DI unit and 2 MaxCap refills at $35 = $99 + $75 = $174 dollars. If all purchased from spectrapure.
25 PPM into a standard 5000ppm capacity cartridge would yield 200 gallons of water. So that is 9 total DI refills (2 in the initial purchase and 7 refill cartridges @ $12 to get 1800 gallons = $62 + $82 = $142
Now if one were to do as you suggest and replace the MaxCap resin after 1/3 and 2/3 with the $14 filterguys RESIN, then the cost is down to $99+$28 Or $127. Will the filterguys resin protect the Silica Buster DI for 1/3 1/3 and 1/3 to get the capacity out of it? Who knows. It does not sound like it would.
That of course is also assuming that BOTH resins have a capacity of 5000ppm
THE BIG DIFFERENCE HERE IS THE FACT THAT THE OUTPUT IS NOT THE SAME. The maxcap should put out cleaner water. Is it worth paying the extra for? That is up to you. Remember 0 tds is not the end all beat all target for some people.
BeanAnimal
Premium Member
Yes of course some of the vendors offer low end products (but will do their best to explain why they are not for your reef and are instead for your drinking water, etc).
We can certainly talk about individual units and features. That goes right along with determining the operating costs of the unit so that it can be compared to others.
Again, operating cost is just one factor. We can consider build quality, expected service life, customer support, parts, extras, and any of a number of other criteria.
From those "factors" we can assign value.
The problem arises when people want to talk about COST but do not understand what factors contribute to cost. So we end up with people who are "happy" but have no idea why, other than the fact that they think they got a good deal.
So we need to be sure that we are talking about the same thing. Is it water quality that we are comparing or is it a cost to get to a know water quality level? Pretty simple when we boil it down. The RO/DI unit is just simple mechanical device (well we can argue of osmosis is mechanical or not).
Bean
carlso63
Reefkeeping since 1977
Since it seems everyone here is just "lobbing hand grenades at each other" anyway:
Interesting to note that in "The Consciencious Marine Aqaurium" the opinion on using RO/DI water at all is basically that it is "...overrated as a panacea for aquarist's problems...in the vast majority of the country (U.S.) dechlorinated, aged tap water is perfectly fine...if you are having troubles with your livestock the quality of your tap supply is one of the last things you should consider...flow, excess nutrient levels in the tank, lighting are all much higher priorities in a reef aquarium..."
I remember reading that, and being fairly surprised as that book is often cited as a good source of information to the beginning and intermediate marine enthusiast.
Interesting how one 'expert' can publish an opinion basically 180 degrees from all the passions expressed here on this thread...?
Bombs Awaaaaaaaay!
:uzi: :hammer: :blown:
Interesting to note that in "The Consciencious Marine Aqaurium" the opinion on using RO/DI water at all is basically that it is "...overrated as a panacea for aquarist's problems...in the vast majority of the country (U.S.) dechlorinated, aged tap water is perfectly fine...if you are having troubles with your livestock the quality of your tap supply is one of the last things you should consider...flow, excess nutrient levels in the tank, lighting are all much higher priorities in a reef aquarium..."
I remember reading that, and being fairly surprised as that book is often cited as a good source of information to the beginning and intermediate marine enthusiast.
Interesting how one 'expert' can publish an opinion basically 180 degrees from all the passions expressed here on this thread...?
Bombs Awaaaaaaaay!
:uzi: :hammer: :blown:
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