BobinCovington
Well-known member
I have a basic low gpd spectrapure RO unit but I do not think it has the DI module. Is the Di module necessary? Should I get an add on DI module?
RO/DI...do I need the DI?
- Thread starter BobinCovington
- Start date
Help Support Reef Aquarium & Tank Building Forum:
Fijiwigi
Active member
The RO will purify the water to about 98% and the DI will give you the other 2% purification from what I understand.
Really depends on your water supply. I use RO only. My inlet water is about 30 TDS and the output from my RO unit is between 0 and 1 TDS.
Actually, I have been thinking of going the opposite way - using DI only. I don't think I would exhaust the DI resin too quickly, and I would sure waste less water!
Actually, I have been thinking of going the opposite way - using DI only. I don't think I would exhaust the DI resin too quickly, and I would sure waste less water!
danno14
That's Dumas!
More quickly than you think! Call the gang at Spectrapure.... for the straight scoop and no anecdotal conjecture. D
Boomer
Well-known member
Lots of people now are using the Kati-Ani which is rechargeable.
My inlet water is about 30 TDS
That is low and something like the KA would be a good choice. Calll the filter guys.
thefilterguys.biz
My inlet water is about 30 TDS
That is low and something like the KA would be a good choice. Calll the filter guys.
thefilterguys.biz
Kurt_Nelson
Well-known member
I've got 80 ppm TDS at the tap. Using DI only prefiltered with a KoldSteril unit, I go through a DI cannister every 50-75 gallons. Pricey, but it all depends on the value you assign to "high flow rate, on demand" pure water with no waste.
OldFishMan
Well-known member
Hello;
You will need to find some information from your local water district or test your water to see if you need RO or RO with DI.
We have good water here where I live in Idaho with a small amount of Chlorine. I use a Carbon pre-filter to remove the Chlorine.
If your TDS is high --- a suggestion would be to use a prefilter 5-micron and then a Carbon filter for Chlorine before the DI unit. Once it's set up about 18-bucks for a 3-pack of the 5-micron filters.
Wikipedia-- Total dissolved solids (often abbreviated TDS) is an expression for the combined content of all inorganic and organic substances contained in a liquid which are present in a molecular, ionized or micro-granular (colloidal sol) suspended form. Generally the operational definition is that the solids must be small enough to survive filtration through a sieve size of two micrometres.
You never can tell what TDS is composed of, RO/DI is good insurance.
-----------------------------------------------------------------------------------
"When we are told something long enough, we tend to believe it!"
"Some Athiest, Somewhere"
Enjoy!
OFM
You will need to find some information from your local water district or test your water to see if you need RO or RO with DI.
We have good water here where I live in Idaho with a small amount of Chlorine. I use a Carbon pre-filter to remove the Chlorine.
If your TDS is high --- a suggestion would be to use a prefilter 5-micron and then a Carbon filter for Chlorine before the DI unit. Once it's set up about 18-bucks for a 3-pack of the 5-micron filters.
Wikipedia-- Total dissolved solids (often abbreviated TDS) is an expression for the combined content of all inorganic and organic substances contained in a liquid which are present in a molecular, ionized or micro-granular (colloidal sol) suspended form. Generally the operational definition is that the solids must be small enough to survive filtration through a sieve size of two micrometres.
You never can tell what TDS is composed of, RO/DI is good insurance.
-----------------------------------------------------------------------------------
"When we are told something long enough, we tend to believe it!"
"Some Athiest, Somewhere"
Enjoy!
OFM
Last edited:
Boomer
Well-known member
Wikipedia is not in touch and is often in error. TDS and their description is true form many decades ago. TDS now, as measured by any city water supply company or any individual, is a measurement of conductivity which measures only ions that have a charge. So, TDS does not measure any levels of molecules, as they uncharged.
If your TDS is high --- a suggestion would be to use a prefilter 5-micron and then a Carbon filter for Chlorine before the DI unit
That is nonsense such filters will actually raise the TDS not lower it, as it is a measurement of conductivity. The chlorine reacts with the carbon surface which gets oxidized and reduces the chorine to chloride which is a charged ion, which thus raises the TDS, which then can be removed by the RO and DI. And most good RO/DI units have the fitlers already.
You will need to find some information from your local water district or test your water to see if you need RO or RO with DI.
Any tap water supply should be run through a RO/DI. A district water test is irrelevant. That should be obvious by your own statement on this post.
You never can tell what TDS is composed of, RO/DI is good insurance.
If your TDS is high --- a suggestion would be to use a prefilter 5-micron and then a Carbon filter for Chlorine before the DI unit
That is nonsense such filters will actually raise the TDS not lower it, as it is a measurement of conductivity. The chlorine reacts with the carbon surface which gets oxidized and reduces the chorine to chloride which is a charged ion, which thus raises the TDS, which then can be removed by the RO and DI. And most good RO/DI units have the fitlers already.
You will need to find some information from your local water district or test your water to see if you need RO or RO with DI.
Any tap water supply should be run through a RO/DI. A district water test is irrelevant. That should be obvious by your own statement on this post.
You never can tell what TDS is composed of, RO/DI is good insurance.
Last edited:
I thought that DI resins only removed charged particles. So if your water is close to zero TDS after RO, what will the added DI do?
Boomer
Well-known member
Yes Don, a DI only removes charged ions only, where does it say otherwisee 
. If one chooses to use low TDS RO that is their choice. The question at hand is if that RO output is say 1 or 2 ppm what is the make-up of that 1-2 ppm ? For me I dont; care really care but amy trying to leave peopel in safe mode. I'm no sure if I have posoted it here or not but have else where. For 35 yeras I ran straight Lake Superior tap water with TDS of 55ppm. And I kept many of those animals alive for years and some up to 15 years and they were not just fish. What TDS one uses in their reef tank is really a choice.
. If one chooses to use low TDS RO that is their choice. The question at hand is if that RO output is say 1 or 2 ppm what is the make-up of that 1-2 ppm ? For me I dont; care really care but amy trying to leave peopel in safe mode. I'm no sure if I have posoted it here or not but have else where. For 35 yeras I ran straight Lake Superior tap water with TDS of 55ppm. And I kept many of those animals alive for years and some up to 15 years and they were not just fish. What TDS one uses in their reef tank is really a choice.Just making sure that I understood DI correctly. Also, for the sake of my education, one of the advantages of RO is that it will remove uncharged molecules small-enough to make it through the prefilters, correct?
(of course there are other advantages, including removing many charged particles more cheaply than DI)
But specifically, something that RO will do that DI won't is remove molecules, correct? (same question repeated, sorry)
Can you give specific examples of things that would make it through prefilter and be caught in an RO system, but would not be caught in a DI-only system (with proper carbon and particle prefilters)?
(of course there are other advantages, including removing many charged particles more cheaply than DI)
But specifically, something that RO will do that DI won't is remove molecules, correct? (same question repeated, sorry)
Can you give specific examples of things that would make it through prefilter and be caught in an RO system, but would not be caught in a DI-only system (with proper carbon and particle prefilters)?
Boomer
Well-known member
remove uncharged molecules
Yes Don the RO will remove most uncharged ions, charged ions and molecules but not all molecules. For example, gases ( CO2, O2, Ammonia, etc.), Chloramine or silicic acid can go with through the RO usually. PO4 is also hard for a RO or even a DI.
If the prefilter has carbon then it can pull out many unwanted organics. The carbon will also react with chlorine and chlorine and convert them to Chlorides which the RO will take too. The ammonia from the Chloramine conversion will make it through but get picked up by the DI. All CO2 will make it through the pre and RO and will get converted on the RO output to HCO3- which the DI will pick up.......
To calculate the effects of CO2 on DI production, divide the CO2 product water concentration in ppm by the sum of the CO2 concentration in ppm plus the product
water TDS in ppm. For example, if you have 4 ppm TDS and 3 ppm CO2 in your RO water, you are wasting 3/7 or 43 % of your anionic DI capacity on CO2 removal.
One can get the CO2 level buy using this CO2 on-line calculator for FW. Don't try to use this for figuring out how much CO2 there is in seawater, as it will be way off.
http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm
something that RO will do that DI won't is remove molecules, correct?
Just to be sure you are sure yes you are correct
Yes Don the RO will remove most uncharged ions, charged ions and molecules but not all molecules. For example, gases ( CO2, O2, Ammonia, etc.), Chloramine or silicic acid can go with through the RO usually. PO4 is also hard for a RO or even a DI.
If the prefilter has carbon then it can pull out many unwanted organics. The carbon will also react with chlorine and chlorine and convert them to Chlorides which the RO will take too. The ammonia from the Chloramine conversion will make it through but get picked up by the DI. All CO2 will make it through the pre and RO and will get converted on the RO output to HCO3- which the DI will pick up.......
To calculate the effects of CO2 on DI production, divide the CO2 product water concentration in ppm by the sum of the CO2 concentration in ppm plus the product
water TDS in ppm. For example, if you have 4 ppm TDS and 3 ppm CO2 in your RO water, you are wasting 3/7 or 43 % of your anionic DI capacity on CO2 removal.
One can get the CO2 level buy using this CO2 on-line calculator for FW. Don't try to use this for figuring out how much CO2 there is in seawater, as it will be way off.
http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm
something that RO will do that DI won't is remove molecules, correct?
Just to be sure you are sure yes you are correct
freetareef
Well-known member
ahh... i use tap water... any thoughts on Kati-Ani boomer? i hear it works great but is becoming almost impossible to get the chems to recharge since the meth problem is running amuck...
DonW
R.I.P.
You can get rooto at most hardware stores. IMO its not worth the work.
Don
Don
Boomer
Well-known member
freetareef
They are fine if your TDS is not to high. Give Jim a call at thefilterguys
They are fine if your TDS is not to high. Give Jim a call at thefilterguys
Similar threads
