TDS Test Results for those of us without an RO/DI
- Thread starter Stray32
- Start date
ironwill723
Well-known member
wow! where did you find that?
superstein61
New member
I agree - you can buy an well built RO/DI at BRS for $130
Economy 4-stage model
although I would recommend spending the extra $30 if you can for the 5 stage model
5-stage
I actually have their higher end model with the built in TDS meter and pressure gauge. They sell it on their site for $199 but they usually have it on ebay as well and you can get it around (seller ReefChili = Bulkreefsupply)
Actually all of their units can be had on ebay 4 cheaper if you are patient:
4 stage economy $99
5 stage regular $119
http://shop.mediabaskets.com/category.sc?categoryId=8
dont know how many he has left..its on the right side of the page
superstein61
New member
have you measured your TDS coming out of the unit? Since you have no DI (just RO) I am betting you still have some TDS in your water. You may be best served adding on a DI canister for $35
With just RO, you are only part way there (which is why the unit cost what it did). Of course, RO only is better than tap water - but unless you also have DI, its doubtful you will be at 0 TDS. I can measure the TDS of water going into my unit, after RO and after DI - and its never 0 after just RO - but always zero after both RO and DI
I have no TDS and nothing to measure..It hasnt shipped yet as I just ordered it the other day...I have read plenty of people getting 0TDS with this unit.
The unit retails for $126 normally..Look at any site.
he got them REALLY cheap from a petsmart screw up in the price and is selling them...That price doesnt reflect anything on the product
The unit retails for $126 normally..Look at any site.
he got them REALLY cheap from a petsmart screw up in the price and is selling them...That price doesnt reflect anything on the product
superstein61
New member
jonreefer - not trying to pick an argument with you - but if you do the research it is HIGHLY unlikely anyone is getting 0 TDS just from that RO unit alone.
Even the top of the line Spectapure membranes are rated at 98% rejection rates. You typically can only get to 0 TDS with RO AND DI
The Coralife unit uses a Dow Filmtec ® TW30-1812-24 24 GPD TFC RO reverse osmosis membrane - which is rated at a 96% rejection rate at 60PSi
So if you have 250 tds water from your tap, with a 96% rejection rate, you will still have 10 tds water. If your PSI is less than 60, your rejection rate will be even less
I have seen my tap water run anywhere from 200 to 500 tds depending on the time of the year so with JUST RO - I would be looking at 8 to 20 TDS water
I would suggest you get a handheld TDS meter and measure the output yourself
Even the top of the line Spectapure membranes are rated at 98% rejection rates. You typically can only get to 0 TDS with RO AND DI
The Coralife unit uses a Dow Filmtec ® TW30-1812-24 24 GPD TFC RO reverse osmosis membrane - which is rated at a 96% rejection rate at 60PSi
So if you have 250 tds water from your tap, with a 96% rejection rate, you will still have 10 tds water. If your PSI is less than 60, your rejection rate will be even less
I have seen my tap water run anywhere from 200 to 500 tds depending on the time of the year so with JUST RO - I would be looking at 8 to 20 TDS water
I would suggest you get a handheld TDS meter and measure the output yourself
Last edited:
Stray32
New member
Let's be practical here guys. I agree that everyone with a large tank (including myself) should eventually get an RO/DI system. I agree that with the price of quality RO water, around 80 cents/gallon, you will have paid for a decent RO/DI system within 12-18 months.
What I don't agree with, is that RO water with a TDS of 2 is going to have a detrimental effect or even a vastly disimilar effect on a system than water with a TDS of 0. Everyone says to shoot for perfection in this hobby, which I can agree with to an extent, but please don't patronize me and tell me that a TDS of 2 is bad for my tank. I am someone who successfully birthed and maintained a reef tank with tap water for over a year until I moved into my new home and noticed that my tap water had a definite odor. Only once in the year did I have a problem with algae and my minimal livestock loss can be attributed to improper QT or lighting (SPS).
I am not trying to argue guys, many of you have been in this hobby longer than me and have more experience. My point is, is that if someone chooses to use bottled RO water instead of investing in an RO/DI system, though it may not be wise financially, it will not effect the success of their tank.
What I don't agree with, is that RO water with a TDS of 2 is going to have a detrimental effect or even a vastly disimilar effect on a system than water with a TDS of 0. Everyone says to shoot for perfection in this hobby, which I can agree with to an extent, but please don't patronize me and tell me that a TDS of 2 is bad for my tank. I am someone who successfully birthed and maintained a reef tank with tap water for over a year until I moved into my new home and noticed that my tap water had a definite odor. Only once in the year did I have a problem with algae and my minimal livestock loss can be attributed to improper QT or lighting (SPS).
I am not trying to argue guys, many of you have been in this hobby longer than me and have more experience. My point is, is that if someone chooses to use bottled RO water instead of investing in an RO/DI system, though it may not be wise financially, it will not effect the success of their tank.
Aqua-World PITT
In Memoriam
Anyone with a tank size over 75-100 gallons should get a R/O DI filter. And the only way we are able to get 0 TDS is Running a 4 stage R/O unit with a extra DI canister. And to keep the level that low you will have the change the DI every 3 months due to discoloration of the DI and the obvious higher TDS. Also changing the bottom filters every 6 months and the membrane every 1 year. That's what we do and constantly provide water at 0-2 TDS.
Tswifty
New member
You can extend the life of your DI by running the "non-color changing" resins, as well as running a 2-DI system if you seem to be blowing through resins quickly... of course the amount of water you make, and quality of the incoming tap water needs to be taken into consideration as well.
Your pre-filters should be changed every 6 months like clockwork, and your RO membrane should last you several years. It's also a good practice to disinfect your unit (see below) when you change your pre-filters as well.
In that system you either use an additional DI or some type of Anion Silica Buster cartridge in front of your final DI. However, you need to monitor the TDS in the line between the 2 DI's. Then once you begin to see TDS between the 2, you simply rotate positions, and add a new one on the end. The ultimate goal as I stated above, is to extend the life on your final DI.
I recently switched to Spectrapure resins and have seen a noticeable increase in the life of my DI resin vs The Filter Guys resins I was using previously. This Spectrapure DI has lasted around 6 months already, and is still showing 0 TDS.
My actual RO/DI unit is the Ocean Reef +1 from The Filter Guys. I also have an additional DI housing, but have not felt the need to use it since moving back to PA.
RO/DI Disinfection Method:
Provided by RC Member AZDesertRat
1. Shut off the water supply
2. Disconnect the 1/4" line from the carbon block up to the RO membrane at the membrane end and stick it in a bucket or the sink.
3. Unscrew the pre-filter and carbon housings, remove the old filters
4. Add no more than 2 or 3 spoonfuls of regular unscented bleach to the pre-filter housing and screw the empty housings back on.
5. Open the water supply and slowly fill the housings until you get flow out the 1/4" line you disconnected.
6. Close the supply and let it sit for a few minutes.
7. Open the supply back up and flush it out until any chlorine odor is gone.
8. Shut it off again, unscrew the housings and add the new cartridges.
9. Open the water supply and let the housings fill, flush out any air and let it run for a minute or two to flush any carbon dust out.
10. Reconnect the 1/4" line to the membrane and you are done until next time.
Your pre-filters should be changed every 6 months like clockwork, and your RO membrane should last you several years. It's also a good practice to disinfect your unit (see below) when you change your pre-filters as well.
In that system you either use an additional DI or some type of Anion Silica Buster cartridge in front of your final DI. However, you need to monitor the TDS in the line between the 2 DI's. Then once you begin to see TDS between the 2, you simply rotate positions, and add a new one on the end. The ultimate goal as I stated above, is to extend the life on your final DI.
I recently switched to Spectrapure resins and have seen a noticeable increase in the life of my DI resin vs The Filter Guys resins I was using previously. This Spectrapure DI has lasted around 6 months already, and is still showing 0 TDS.
My actual RO/DI unit is the Ocean Reef +1 from The Filter Guys. I also have an additional DI housing, but have not felt the need to use it since moving back to PA.
RO/DI Disinfection Method:
Provided by RC Member AZDesertRat
1. Shut off the water supply
2. Disconnect the 1/4" line from the carbon block up to the RO membrane at the membrane end and stick it in a bucket or the sink.
3. Unscrew the pre-filter and carbon housings, remove the old filters
4. Add no more than 2 or 3 spoonfuls of regular unscented bleach to the pre-filter housing and screw the empty housings back on.
5. Open the water supply and slowly fill the housings until you get flow out the 1/4" line you disconnected.
6. Close the supply and let it sit for a few minutes.
7. Open the supply back up and flush it out until any chlorine odor is gone.
8. Shut it off again, unscrew the housings and add the new cartridges.
9. Open the water supply and let the housings fill, flush out any air and let it run for a minute or two to flush any carbon dust out.
10. Reconnect the 1/4" line to the membrane and you are done until next time.
Aqua-World PITT
In Memoriam
Yeah we make 600 gallons every day.
Tswifty
New member
That's not ENTIRELY true, and you can't make generalizations like that... you can get away with A LOT of things depending on the inhabitants you choose. Which is the main topic that was not touched upon here.
FOWLR's, Softy's, even a lot of LPS are tolerant of questionable water quality, and don't need "strict" params to flourish.
However, try running a successful SPS dominant reef where you strive daily to drive down phosphate and nitrate numbers to an undetectable amount. By adding water with a TDS of ANYTHING, you are taking 2 steps back.
Tswifty
New member
That's fine. I certainly do not take offense.
TDS is made up of all kinds of impurities or filterable solids... which could be anything from phosphates to copper... etc... etc...
The point is... you have no idea what that 2 ppm is composed of. It's not a standard makeup across the board or anything like that. For instance, you can't assume that a 2 ppm TDS reading out of my old apartment's water in Ohio would be the same as a 2 ppm TDS reading in your water here in PA. So it could be similar to a 0 ppm reading, or it could be vastly different. The problem isn't exactly in the ppm reading itself, but rather what that reading is comprised of... and honestly you just don't know. (I don't know how you would figure it out either).
I'm not a water expert by far though... just have picked up some things here and there, and like to try and minimize any outside variables that could potentially have a negative impact on my tank. Especially the ones that are as easy to control as using pure water.
Here's an article by RHF on purifying water for the aquarium.
http://www.reefkeeping.com/issues/2005-05/rhf/index.php
cloakerpoked
New member
We act as though the ocean is as sterile as we try to keep our reef tanks, but that's simply not the case. I'm going to disagree with the nitrate problem. I've run a reef tank on a DSB with way more LR than I need for 2 years now, and have NEVER tested nitrates above 0ppm. I've also never added RO/DI water to my tank, and evaporate quite a lot of it off my tank daily (probably upwards of 2 gallons.) I have upwards of 25 different SPS frags/colonies growing in the tank, all of them encrusting their plugs, coloring up nicely, and showing reasonable growth.
Now, I did just invest in an RO/DI filter for the tank a few days ago right before this thread started. I have city water, which I'm sure has plenty of impurities in it...but I'm wondering if anybody has actually done a quantitative study to see what it is. Its feasible that some of those ppm you test come from helpful ions like Calcium, Iron (in small quantities not a bad thing), Magnesium, etc etc. If we strive for 400-450 ppm of calcium alone, then I highly doubt that 2, or even 10ppm of something being added after RO filtering would be harmful. You figure, that is highly unlikely to be straight copper, phosphates, etc.
Bottom line...in my own experience, I've chosen to get an RO/DI filter to greatly reduce my phosphates because slime algae is starting to grow in the frag tank (very little of it, but I don't like it growing at all.) and because I want to reduce the overall hard city water that we get at my house. Am I going to buy a TDS meter and watch it every month to know when to sink another $50 into filters? no. Am I worried about my corals dying, or experiencing stunted growth? no. But I will watch the overall growth pattern of them to see if there seems to be a difference. Of course, there are always variables that we can't account for in the tank, so it's impossible in my case to do a controlled experiment.
Now, I did just invest in an RO/DI filter for the tank a few days ago right before this thread started. I have city water, which I'm sure has plenty of impurities in it...but I'm wondering if anybody has actually done a quantitative study to see what it is. Its feasible that some of those ppm you test come from helpful ions like Calcium, Iron (in small quantities not a bad thing), Magnesium, etc etc. If we strive for 400-450 ppm of calcium alone, then I highly doubt that 2, or even 10ppm of something being added after RO filtering would be harmful. You figure, that is highly unlikely to be straight copper, phosphates, etc.
Bottom line...in my own experience, I've chosen to get an RO/DI filter to greatly reduce my phosphates because slime algae is starting to grow in the frag tank (very little of it, but I don't like it growing at all.) and because I want to reduce the overall hard city water that we get at my house. Am I going to buy a TDS meter and watch it every month to know when to sink another $50 into filters? no. Am I worried about my corals dying, or experiencing stunted growth? no. But I will watch the overall growth pattern of them to see if there seems to be a difference. Of course, there are always variables that we can't account for in the tank, so it's impossible in my case to do a controlled experiment.
superstein61
New member
Nate - that may be true is some areas, not true in others. The big difference is we are dealing with such a small, closed system of water in our tanks so the margin of error is much less.
I have no doubt people have been and can be successful in keeping lots of items using plain old tap water. However, using 0 tds water helps eliminate one risk factor and thereby IMO enhances one's chance of success in keeping everything, eliminating nuisance algae, etc.
And my biggest point on the thread is if you are investing in a ro/di unit, it makes no sense to just go part way and only get RO. You will never get the 0 TDS results you want with these units unless you have both RO and DI.
Last edited:
cloakerpoked
New member
Did a little bit of research. The average calcium concentration in Pittsburgh tap water is 53.2ppm. http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2488164
If you're testing 200ppm, that means your calcium concentration may be close to 25% or so, so right off the bat, your TDS composition is actually much lower in terms of harmful ions.
Besides calcium, magnesium, and sodium, there seems to be (on average) relatively much smaller concentrations of trace elements such as copper (.001-.005ppm), zinc (.01-.1 ppm), Mangonese, Iron, Nickel, and Boron. Most of it is composed of the above.
Obviously I can't say for certain that's what Pittsburgh tap water has as far as the trace elements, and can't even be certain of the reliability of it, since I read that info on another forum and not a formal study, but it would be interesting to see if the water authority has any info on the mineral composition of their tap water. They probably would.
The one scenario that I can think of where TDS could be a problem would be with a "contamination event" where some kind of harmful ion could be in abnormally high concentrations in the water. Was reading another thread where he had a tank crash from a high zinc concentration all of a sudden, so a filter of some kind would definitely be beneficial at this point.
Over time, since we are adding water for top off (almost 1% per day in my case) that water would, over time add up as far as the Cu, Ni, and Zn concentrations would be concerned, even doing regular water changes wouldn't help it if it was just exchanging some tap water for others. This would be a very slow process. You figure I'd increase the concentration of my Cu content by 30%, then do a water change of 10%. That would dilute the concentration somewhat, but very slowly, it would add up in the tank. The proverbial 3 steps forward, 2 steps back. An RO filter by itself would extend this process greatly, but not indefinitely. Sooner or later (whether that be 5 years, or 30 years I can't say) those elements would reach toxic levels. Now if the tank were drained, larger water changes done with RO water, etc, that would further dilute the water, and forstall a crash for an indeterminate period of time.
As stated above, RO/DI is definitely safer, but I personally feel as though it may be an unnecessary precaution, and think that the RO/DI supporters in this forum may have been needlessly critical of the purchase of an RO unit.
If you're testing 200ppm, that means your calcium concentration may be close to 25% or so, so right off the bat, your TDS composition is actually much lower in terms of harmful ions.
Besides calcium, magnesium, and sodium, there seems to be (on average) relatively much smaller concentrations of trace elements such as copper (.001-.005ppm), zinc (.01-.1 ppm), Mangonese, Iron, Nickel, and Boron. Most of it is composed of the above.
Obviously I can't say for certain that's what Pittsburgh tap water has as far as the trace elements, and can't even be certain of the reliability of it, since I read that info on another forum and not a formal study, but it would be interesting to see if the water authority has any info on the mineral composition of their tap water. They probably would.
The one scenario that I can think of where TDS could be a problem would be with a "contamination event" where some kind of harmful ion could be in abnormally high concentrations in the water. Was reading another thread where he had a tank crash from a high zinc concentration all of a sudden, so a filter of some kind would definitely be beneficial at this point.
Over time, since we are adding water for top off (almost 1% per day in my case) that water would, over time add up as far as the Cu, Ni, and Zn concentrations would be concerned, even doing regular water changes wouldn't help it if it was just exchanging some tap water for others. This would be a very slow process. You figure I'd increase the concentration of my Cu content by 30%, then do a water change of 10%. That would dilute the concentration somewhat, but very slowly, it would add up in the tank. The proverbial 3 steps forward, 2 steps back. An RO filter by itself would extend this process greatly, but not indefinitely. Sooner or later (whether that be 5 years, or 30 years I can't say) those elements would reach toxic levels. Now if the tank were drained, larger water changes done with RO water, etc, that would further dilute the water, and forstall a crash for an indeterminate period of time.
As stated above, RO/DI is definitely safer, but I personally feel as though it may be an unnecessary precaution, and think that the RO/DI supporters in this forum may have been needlessly critical of the purchase of an RO unit.
superstein61
New member
Nate - the problem with averages are that well, they are averages. I have seen huge swings in the TDS values of my incoming Tap Water depending on time of the year, the weather, etc (and I am not obsessive about checking it - just do so every so often since I have a TDS meter built in to my RO/DI unit). So you would really never know what the water company is adding / dealing with at any particular time if you just used plain old tap water. I am sure many times you would be fine, but others you may not. I guess I am just the type who would prefer not to take the chance - but thats me. Not saying its wrong or right.
As to just RO vs. RO/DI - all I can say there is my perspective is if you are worried about your tap water enough to invest in a RO unit, you might as well spend the extra $20 to $30 to make it a full RO/DI unit. But I manage finances for a living so maybe I have a different outlook than others.
Anyway, I think we beat this subject to death.
Take care
As to just RO vs. RO/DI - all I can say there is my perspective is if you are worried about your tap water enough to invest in a RO unit, you might as well spend the extra $20 to $30 to make it a full RO/DI unit. But I manage finances for a living so maybe I have a different outlook than others.
Anyway, I think we beat this subject to death.
Take care
Similar threads
