RO/DI question

perfectdark

perfectdark

Active Member
Ok so I am very very close to pulling the trigger on an RO/DI unit. My question is, the literature for the various units I am looking at state the percentage of rejected TDS, some are 96% some are 99%. In reality how big of a difference is this? I know we strive for 0 but would 96% really be a huge leap from 99? Thanks in advance.
 
t316

t316

Active Member
I don't even look at the rejection rate. You are looking for 0 TDS reading, which they all should give you with new filters.
 
nordy

nordy

Active Member
What is the cost difference between the 96 vs the 99? Depending on price, it may be a case of paying a large amount for a miscule improvement and even then I would wonder how reliable the TDS claims are and whether that 3% point difference would also be within the range of variation of individual unit performance that you may find even among identical units. I just got my RO/DI unit and shopped a 4 stage unit by price ($279). Not always the best way to purchase something, but for my tank going from tap water to decent quality RO/DI is a huge advance.
I thought about giving the dog RO/DI water in her drinking bowl, but she still prefers the toilet.
 
bang guy

bang guy

Moderator
What is the cost difference between the 96 vs the 99?
The difference is Phosphate and Silicates. The 96% unit is letting about 30% of the Phosphate and Silicate through the filter. If your filtration can handle the Phosphate and you don't care about Diatoms then this unit will work fine.
 
perfectdark

perfectdark

Active Member
Originally Posted by Bang Guy
http:///forum/post/2512676
The difference is Phosphate and Silicates. The 96% unit is letting about 30% of the Phosphate and Silicate through the filter. If your filtration can handle the Phosphate and you don't care about Diatoms then this unit will work fine.
Ya, thanks Bang I had a feeling it was something, other wise why would they note it. Makes my decision an easy one now..
 
rs1831

rs1831

Active Member
Originally Posted by PerfectDark
http:///forum/post/2512835
I like air water and ice.. bang for buck they seem to have a large selection with many options.

Good unit. Thats what I have and I've never had a problem. Plus they have really good customer service.
Good luck.
 
ameno

ameno

Active Member
I use the typhoon three, great unit

I didn't know that about the 96% - 99% thing, that's good to know. I guess the 96% would be more of RO water were 99% would be DI.
 
cpg

cpg

Member
I just bought a 50gal per day coralife 3 stage unit last weekend. Did I miss something by not thinking through this 96% vs 99% debate?
 
perfectdark

perfectdark

Active Member
Originally Posted by CPG
http:///forum/post/2512896
I just bought a 50gal per day coralife 3 stage unit last weekend. Did I miss something by not thinking through this 96% vs 99% debate?
Not sure... Phosphates and silicates can be a big headache to some of us, they're not necessarily the end of the world for your tank but besides the look of a brown diatom bloom. Ultra high levels are bad and if you didnt know that they were comming from your water source then you would be going mad trying to figure out where you were adding more nutrients than your tank can handle. High nutrient levels are another cause for phosphates.
 
t316

t316

Active Member
Originally Posted by PerfectDark
http:///forum/post/2512987
Not sure... Phosphates and silicates can be a big headache to some of us, they're not necessarily the end of the world for your tank but besides the look of a brown diatom bloom. Ultra high levels are bad and if you didnt know that they were comming from your water source then you would be going mad trying to figure out where you were adding more nutrients than your tank can handle. High nutrient levels are another cause for phosphates.
Just something to keep in mind...the brown on the substrate is not caused by water replacement quality alone. I use RODI water with a 0 TDS reading and I still deal with it occassionally. Other factors include overfeeding, bioload, lighting, etc.
 
perfectdark

perfectdark

Active Member
Originally Posted by T316
http:///forum/post/2513890
Just something to keep in mind...the brown on the substrate is not caused by water replacement quality alone. I use RODI water with a 0 TDS reading and I still deal with it occassionally. Other factors include overfeeding, bioload, lighting, etc.
Hence the second part of my statment above
 
B

blackaero1

Guest
Have you considered a straight DI unit like the Reef Commander? A little more cost up front but cheaper in the long run. 2 benefits are 1-there is no waste water and 2- it flows as fast as a hose for teh most part so you won't take hours to make a few gallons of water.
 
bang guy

bang guy

Moderator
Originally Posted by blackaero1
http:///forum/post/2514705
Have you considered a straight DI unit like the Reef Commander? A little more cost up front but cheaper in the long run. 2 benefits are 1-there is no waste water and 2- it flows as fast as a hose for teh most part so you won't take hours to make a few gallons of water.

I'm thinking it would be more expensive in the long run because you have to replace the beads a LOT more often with straight DI.
 
scopus tang

scopus tang

Active Member
Originally Posted by Bang Guy
http:///forum/post/2512676
The difference is Phosphate and Silicates. The 96% unit is letting about 30% of the Phosphate and Silicate through the filter. If your filtration can handle the Phosphate and you don't care about Diatoms then this unit will work fine.
Bang Guy, how does a 3% difference equate to 30%, and why just phospahte and silicate?
 
florida joe

florida joe

Well-Known Member
Originally Posted by CPG
http:///forum/post/2512896
I just bought a 50gal per day coralife 3 stage unit last weekend. Did I miss something by not thinking through this 96% vs 99% debate?
I think you are ok I am running the coralife 4 stage the forth stage is for deionization in this unit and is suppose to bring the water to 99.9% pure I believe your 3 stage unit is rated for 99%
 
gmann1139

gmann1139

Active Member
Originally Posted by Nordy
http:///forum/post/2512649
I thought about giving the dog RO/DI water in her drinking bowl, but she still prefers the toilet.
More flavor there.
Originally Posted by ameno
http:///forum/post/2512850
I guess the 96% would be more of RO water were 99% would be DI.
I doubt it. Our DI unit at work would fill up awful fast if it was removing 3% of the waste as ionics. My guess is that it just filters smaller particles like the silicates and phosphates. Theoretically it should clog faster then, but I'm guessing they've engineered around that problem.
Dark, have you thought about getting the TDS reading of your tap now? Might help decide if you need that extra 3%.
 
bang guy

bang guy

Moderator
Originally Posted by Scopus Tang
http:///forum/post/2514903
Bang Guy, how does a 3% difference equate to 30%, and why just phospahte and silicate?

Phosphates and Silicates and Water are usually the only molecules small enough to pass through a 96% RO membrane. So, the membrane on the 96% system eliminates 99.99% of everything except Phosphate and Silicates and removes about 30% of the Silicates and Phosphate then the result is that the membrane removed 96% of the contaminants. The actual numbers depend completely on what's actually in your source water.
 
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