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deionization instead of ro
- Thread starter cjsrch
- Start date
I have never heard of 75-100 before. Always thought it had to be one or the other.
The 100 GPD has a lower % rejection rate (about 90%), so it will result with water with higher TDS. The 75 is usually a better choice as it usually has a 98% rejection rate which would cause your DI to last longer.
Do you have a pressure guage attached? If so, what pressure does it run at.
Low pressure (below 40 psi) could cause the rejection rate to fall, thus allowing more TDS through and excessive (above 60 psi) could damage the membrane.
The 100 GPD has a lower % rejection rate (about 90%), so it will result with water with higher TDS. The 75 is usually a better choice as it usually has a 98% rejection rate which would cause your DI to last longer.
Do you have a pressure guage attached? If so, what pressure does it run at.
Low pressure (below 40 psi) could cause the rejection rate to fall, thus allowing more TDS through and excessive (above 60 psi) could damage the membrane.
GUYS! EXACTLY im placing ro unit next to the fridge. its the only place on that side of the house with water .... the sink is on an island and everything else is on other side of house!
no our soil has EXCESS arsinic. they actualy stoped new development ( 2nd half of neiborhood) because of it/ they have to rotate the soil or some crap like that. ( i think we are built on an old sugercane farm and those old timers use to use arsinic for incecticide)
no our soil has EXCESS arsinic. they actualy stoped new development ( 2nd half of neiborhood) because of it/ they have to rotate the soil or some crap like that. ( i think we are built on an old sugercane farm and those old timers use to use arsinic for incecticide)
Rob, I have been looking at the output of your RO/DI.Rob_Reef_Keeper":2wdv1a18 said:Tap - 350
RO - 35
DI (1) - 4
DI (2) - 0
If your tap TDS is 350 ppm and after the RO it's 35 ppm, that means your rejection is 90%. This would imply that you have a 100 GPD system. If you changed the RO membrane to a 75 GPD membrane, you would end up with 7 ppm @ a 98% rejection rate.
That said, even if you have a TDS of 35 ppm, a DI should bring it down to 0 ppm. I do not understand why you should need 2 DI cartridges to get 0 ppm.
I used to use a product called Tap Water Purifier. It was basically a DI cartridge with a little carbon (no RO) and I used to get 0 TDS with 200 ppm tap. The only problem is that it would get exhausted pretty quickly.
In your case, because your RO produces 35 ppm, the DI should carry it to 0 ppm, but the DI cartridge will not last as long as a RO with a higher rejection rate.
Something is not quite right here.
Fastmarc, how is the GPD rating determined from the rejection rate? I always thought they are independent...
Depends on the flow rate thru the DI portion, the TDS may be higher than "0" ppm. Rob's first DI is getting pretty much all used up, and may needed to be recharged or replaced.
Depends on the flow rate thru the DI portion, the TDS may be higher than "0" ppm. Rob's first DI is getting pretty much all used up, and may needed to be recharged or replaced.
Rob_Reef_Keeper":242toeev said:I replace both DI catridges every 3 months.
I have not seen a 98 % rejection rate RO system. I thought that all RO get ~90 % rejection rate.
I don't use ro/di so actually can not make any comment.
But in general filters will remove more depending on how "seasoned" (for lack of a better word) they are and how much stuff to be filtered out is in the water. Obviously, at some low concentration the filter will remove nothing. Because it is operating at the limit of the filtering capacity. But with a concentration of a million times that amount the filter would probably remove almost 99.999999%. But still leave that small concentration in the water.
seven ephors":2rs67utk said:Fastmarc, how is the GPD rating determined from the rejection rate? I always thought they are independent...
I don't think that's what Marc is saying.
I believe he's saying that most commonly available membranes rated for 100 GPD are typically designed for high output and tend to not have as good of a rejection rate, ie. 90% as opposed to the 98% often seen for the lower flow models. I discussed this with an RO vendor on the phone a few years ago and was told the same thing...
beaslbob":x9x28ecl said:But in general filters will remove more depending on how "seasoned" (for lack of a better word) they are and how much stuff to be filtered out is in the water. Obviously, at some low concentration the filter will remove nothing. Because it is operating at the limit of the filtering capacity. But with a concentration of a million times that amount the filter would probably remove almost 99.999999%. But still leave that small concentration in the water.
IME that is not how an RO works. How well it filters/rejects has more to do with what kinds of stuff is in the input water (ie. what type of contaminants are being removed), operating water pressures, water temps, etc. If input TDS goes up/down (assuming same location, water temps, pressures, etc.) IME output water TDS goes up/down as well and the rejection rate stays about the same.
Well I am crossing my fingers for tomorrows water test. I have the water company coming out tomorrow to test my water.
If the water is that bad and my RO/DI/DI is not removing all the bad stuff fueling my algae problems it may be time to call it quits.
_________________
Honda VTR1000F
If the water is that bad and my RO/DI/DI is not removing all the bad stuff fueling my algae problems it may be time to call it quits.
_________________
Honda VTR1000F
Rob_Reef_Keeper":389dwcpn said:If the water is that bad and my RO/DI/DI is not removing all the bad stuff fueling my algae problems it may be time to call it quits.
Before throwing in the towel I would try a membrane with a better rejection rate or a water softener prefilter (read that it helps somewhere)....
My TDS out of the tap is ~130 and after the RO is 0-3. I just found that there is still NH3, PO4 and NO2 in the RO output leading to my algae problems. I just ordered a DI cartridge to add on and pray that those levels drop to 0 so my waterchanges and topoff water aren't fueling the algae anymore . :evil:
- steve
Rob.
And regardless of how pure you make the water you put in your tank, there will still be livestock that must be fed resulting in phosphates and nitrates anyway. No filter/skimmer or anything else will be able to remove 100% of those things. Resulting plant life in your tank feeding on those things. Just the way it is.
And regardless of how pure you make the water you put in your tank, there will still be livestock that must be fed resulting in phosphates and nitrates anyway. No filter/skimmer or anything else will be able to remove 100% of those things. Resulting plant life in your tank feeding on those things. Just the way it is.
beaslbob":3o2krjgk said:And regardless of how pure you make the water you put in your tank, there will still be livestock that must be fed resulting in phosphates and nitrates anyway. No filter/skimmer or anything else will be able to remove 100% of those things. Resulting plant life in your tank feeding on those things. Just the way it is.
I agree - but using pure source water can go a long way in keeping nutrient levels low enough that whatever minor algae growths are present can easily be kept in check by algae-eating critters. Poor quality source water used for top-off and mixing-up water changes can be a very significant source of nuisance algae fueling nutrients. If nutrient imports/exports are balanced and there are adequate algae grazing critters present, hair algae should not be an issue.
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