last RO/di question

[floridian reefer]

when do yall change the filters in your ro unit? how do you know to change wich one? what tds reading is "too" high? can i add a DI stage to my ro unit?

 

 

just got a super good deal on a RO unit and was just wondering thanks for the help!!

[MedicBMC]

1 tds is too high in my opinion.

 

You know when to change which filters by checking pre- and post- DI numbers.

[floridian reefer]

im sorry i didnt understand the second part.

[nano_keeper30]

he means nothing since you do not have a DI on your RO unit. However if you did, he means check the water after it comes out of the membrane and if you had a DI stage, check it when it comes out of that.

 

Yes, you can add a DI unit to your existing RO. Just means adding another step to your RO system. The DI is the last step of the whole RO processes so its not like you need to loop it in between anything.

 

Membrate to DI Canister DI canister output to storage container.

[mastahluong]

im sorry i didnt understand the second part.

With an RODI unit you should have a TDS meter attached "pre" and "post" DI cartridge. The TDS number should be around 3-6 TDS pre DI filter(RO only water) and 0TDS post DI filter(RODI water). MedicBMC is saying when those TDS number read too high then it is time to change your filters.

 

this is what I use

http://www.tdsmeter.com/products/dm1.html

 

As far as when to change the filters, the TDS meter will let you know when you need to change them. There is not really a standard to changing them since everyone will have different source's of water with varying TDS. Try and change filters as one set, except your RO filter, those should last a little bit longer than your pre-filters. The pre-filters are there to filter out larger particles.

[floridian reefer]

With an RODI unit you should have a TDS meter attached "pre" and "post" DI cartridge. The TDS number should be around 3-6 TDS pre DI filter(RO only water) and 0TDS post DI filter(RODI water). MedicBMC is saying when those TDS number read too high then it is time to change your filters.

 

this is what I use

http://www.tdsmeter.com/products/dm1.html

 

As far as when to change the filters, the TDS meter will let you know when you need to change them. There is not really a standard to changing them since everyone will have different source's of water with varying TDS. Try and change filters as one set, except your RO filter, those should last a little bit longer than your pre-filters. The pre-filters are there to filter out larger particles.

 

 

ok cool thanks thats what i was wondering, when to change the pre filters..... now what tds reading is too high? i buy water from the pet store right now and my tds meter says it at 8.

[nano_keeper30]

ok cool thanks thats what i was wondering, when to change the pre filters..... now what tds reading is too high? i buy water from the pet store right now and my tds meter says it at 8.

 

LFS are in buisness to make money and spend as little as possible. So that means they are not always on the up and up.

 

Id try going to your local supermarket that has the self serve RO units (.39 cents a gallon typically) and check the TDS there. You might be surprised. Before I got tired of going to the supermarket and got my own RO DI unit, my local markets never had a TDS reading more than 3...1-2 was common.

[floridian reefer]

LFS are in buisness to make money and spend as little as possible. So that means they are not always on the up and up.

 

Id try going to your local supermarket that has the self serve RO units (.39 cents a gallon typically) and check the TDS there. You might be surprised. Before I got tired of going to the supermarket and got my own RO DI unit, my local markets never had a TDS reading more than 3...1-2 was common.

 

 

wow, ill have to check like publix , i went to walmart and it was like 54, my tap is 65!!!

[AZDesertRat]

The prefilter and carbon block have very little to absolutely nothing to do with TDS, they are there to protect the RO membrane from TSS, suspended solids, particulates or big stuff not TDS, dissolved solids much smaler than the TSS and chlorine.

 

The TDS mete4r DOES NOT tell you when you need to change the prefilter and carbon, you change them every 6 months like clockwork regardless of the amout of water you have made to keep the membrane operating correctly. The TDS meter will tell you the RO membrane and DI resin condition which is what it is designed for.

 

The RO only TDS should be 96-98% less than yopr tap water TDS in a properly functioning RO system. As an example say you have the national average TDS of around 250 you should expect to see somewhere between 5 and 10 TDS in your RO water. If it is higher than that it is either time for a new RO membrane or you may possibly have a system with the very inefficienct 100GPD Dow Filmtec membrane which is not an RO membrane at all but a nano filter which is only 90% effcient.

 

You can easily calculate your rejection rate or removal efficiency like this. Tap water TDS - RO only TDS divided by the tap water TDS x 100 (example 250-10=240, 240/250=.96, .96x100=96% rejection rate or removal efficiency) which is about the minimum you want to see. As an example my tap water TDS varies between 650 and 800 and my RO only TDS averages between 3 and 5 which averaged over the last 18 months is 99.35% rejection which is very very good.

 

Adding a DI stage will get your TDS down to 0 and depending on how efficient the RO is it may stay there for months before requiring a resin change at 1-2 TDS.

 

I would never buy from a vending machine, they are hit and miss at best since they do not fall under any health regulations. You are at the mercy of their maintenance and that usually consists of spraying some bleach on the nozzle and maybe changing the prefilter which as you remember I said earlier does nothing for TDS removal. If you must purchase water buy either bottled distilled water or try to find a staffed water and ice type store where they will test the TDS in your presence. Another option is purchase your own TDS meter ($20-$25) and test it yourself before buying in quantity.

[floridian reefer]

The prefilter and carbon block have very little to absolutely nothing to do with TDS, they are there to protect the RO membrane from TSS, suspended solids, particulates or big stuff not TDS, dissolved solids much smaler than the TSS and chlorine.

 

The TDS mete4r DOES NOT tell you when you need to change the prefilter and carbon, you change them every 6 months like clockwork regardless of the amout of water you have made to keep the membrane operating correctly. The TDS meter will tell you the RO membrane and DI resin condition which is what it is designed for.

 

The RO only TDS should be 96-98% less than yopr tap water TDS in a properly functioning RO system. As an example say you have the national average TDS of around 250 you should expect to see somewhere between 5 and 10 TDS in your RO water. If it is higher than that it is either time for a new RO membrane or you may possibly have a system with the very inefficienct 100GPD Dow Filmtec membrane which is not an RO membrane at all but a nano filter which is only 90% effcient.

 

You can easily calculate your rejection rate or removal efficiency like this. Tap water TDS - RO only TDS divided by the tap water TDS x 100 (example 250-10=240, 240/250=.96, .96x100=96% rejection rate or removal efficiency) which is about the minimum you want to see. As an example my tap water TDS varies between 650 and 800 and my RO only TDS averages between 3 and 5 which averaged over the last 18 months is 99.35% rejection which is very very good.

 

Adding a DI stage will get your TDS down to 0 and depending on how efficient the RO is it may stay there for months before requiring a resin change at 1-2 TDS.

 

I would never buy from a vending machine, they are hit and miss at best since they do not fall under any health regulations. You are at the mercy of their maintenance and that usually consists of spraying some bleach on the nozzle and maybe changing the prefilter which as you remember I said earlier does nothing for TDS removal. If you must purchase water buy either bottled distilled water or try to find a staffed water and ice type store where they will test the TDS in your presence. Another option is purchase your own TDS meter ($20-$25) and test it yourself before buying in quantity.

 

 

 

thank you, that is very helpful.

[floridian reefer]

i just picked up this one for $20 without the tank, it has the three pre filters.... what would i use in which order? and the tube on the very top, is that necesary on it it just sys taste ond odor remover so im guessing its just a carbon filter? the one below that is the RO filter i know, thnaks!

[floridian reefer]

ANYBODY

[Dani3d]

My TDS is at 2ppm right now and I will wait until it is around 5ppm before I replace the filters. 2ppm is like nothing.

 

when do yall change the filters in your ro unit? how do you know to change wich one? what tds reading is "too" high? can i add a DI stage to my ro unit?

 

 

just got a super good deal on a RO unit and was just wondering thanks for the help!!

[Rome]

I always change mine out when my TDS reaches around 5ppm also, I think you should always aim for 0, but anything less then 10 is acceptable

[AZDesertRat]

Anything over 1 TDS is not acceptable. DI resin begins to release weakly ionized substances like phosphates, silicates and nitrates even before it is exhausted and since they are weakly ionized them may not register on a hobbyist grade TDS meter. Do not wait until anything over 1-2 period or you are asking for trouble.

 

As far as filters for your unit. Take a look at the 1 micron or better yet 0.5 micron prefilter and 0.5 micron carbon block found on sale here:

http://www.spectrapure.com/email/customer-...eciation.html#1

Two carbons are awaste of money and unnecessary if you are using a good quality prefilter and single carbon block, that way the other carbon does not have to function as a secondary prefilter which is the case with many RO and RO/DI vendors.

Use that second empty canister as a full size vertical 20 oz DI filter with a little replumbing and a DI cartridge, taht way you really get some benefit out of it.

 

 

Do not listen to people saying things like " I change my filters when I get to 5 TDS" etc. Again, prefilters and carbons have nothing to do with removing TDS therefore waiting until you see a TDS reading could be damaging to the RO membrane which is actually what removes the TDS along with the DI resin. Prefilters and carbons remove things in the micron ranges like 1 to 10 microns and larger or suspended solids, membranes and DI resmove things in the 0.0001 micron range or TDS, dissolved solids not particulates and sediments.

 

You are correct, you do not need nor want the taste and odor filter, it actually adds TDS to the water as the carbon degrades and turns to dust with usage.

 

Make sure to test your RO rejection rate before ordering any replacements though, if the membrane is not working well you will be out an additional $30-$40 or more for a membrane and matched flow restrictor and that cost plus all the filters and DI just about equal the cost of a new CSP-DI with all the bells and whistles like a dual inline TDS meter, inline pressure gauge, ful size DI and a tested 90 GPD RO membrane. Unfortunately used units usually do not turn out to be the deal we thing they are initially. I have been there myself.

[floridian reefer]

Anything over 1 TDS is not acceptable. DI resin begins to release weakly ionized substances like phosphates, silicates and nitrates even before it is exhausted and since they are weakly ionized them may not register on a hobbyist grade TDS meter. Do not wait until anything over 1-2 period or you are asking for trouble.

 

As far as filters for your unit. Take a look at the 1 micron or better yet 0.5 micron prefilter and 0.5 micron carbon block found on sale here:

http://www.spectrapure.com/email/customer-...eciation.html#1

Two carbons are awaste of money and unnecessary if you are using a good quality prefilter and single carbon block, that way the other carbon does not have to function as a secondary prefilter which is the case with many RO and RO/DI vendors.

Use that second empty canister as a full size vertical 20 oz DI filter with a little replumbing and a DI cartridge, taht way you really get some benefit out of it.

 

 

Do not listen to people saying things like " I change my filters when I get to 5 TDS" etc. Again, prefilters and carbons have nothing to do with removing TDS therefore waiting until you see a TDS reading could be damaging to the RO membrane which is actually what removes the TDS along with the DI resin. Prefilters and carbons remove things in the micron ranges like 1 to 10 microns and larger or suspended solids, membranes and DI resmove things in the 0.0001 micron range or TDS, dissolved solids not particulates and sediments.

 

You are correct, you do not need nor want the taste and odor filter, it actually adds TDS to the water as the carbon degrades and turns to dust with usage.

 

Make sure to test your RO rejection rate before ordering any replacements though, if the membrane is not working well you will be out an additional $30-$40 or more for a membrane and matched flow restrictor and that cost plus all the filters and DI just about equal the cost of a new CSP-DI with all the bells and whistles like a dual inline TDS meter, inline pressure gauge, ful size DI and a tested 90 GPD RO membrane. Unfortunately used units usually do not turn out to be the deal we thing they are initially. I have been there myself.

 

thank you for the great information!!! so stick withthe filters every 6 months, any membrane when testing over 0 for di, and 3 with RO. now how do you test rejection rate? what is that? i asume it the rate at which the water is rejected but what does that mean?

[AZDesertRat]

Rejection rate is the RO removal efficiency which should be 96-98%. By that I mean whatever your tap water TDS is, the RO only TDS should only be 2 to 4% of that number. You cannot say a RO TDS of 3 or 4 or whatever, that means nothing if you don't know what the tap TDS was to begin with. So its 6 months on the prefilter and carbon block, for the RO membrane its when the membrane is no longer 96 to 98% efficient which is the point where DI starts having to act as a crutch for a poorly performing membrane and gets expensive and anything over 1 on a consistent basis for the DI.You do not want to regulate the pressure, more is better for a membrane. 40 psi is the bare minimum with 60 being good and 90 -100 even better. Membranes perform better at higher pressures as well as make water faster.You feed the RO units from your cold water supply line, either with a kitchen faucet adapter, a brass wye on a hose bib or washing machine cold water supply line or garden hose or plumbed permanently to a cold water line under a sink or close to an appliance like the hot water heater or washer. Never ever try to blend or temper the watre temperature, cold water only. Hot or even warm water over 113 degrees will melt a TFC RO membrane in a heartbeat. If you have a water softener always use softened cold water.You hook it up with the prefilter first. carbon second, then up to the RO membrane, place the IN TDS probe at this point so it measures RO only TDS, then to the DI filter and finally the OUT TDS probe so you get final RO/DI TDS. Do not concern yourself with tap TDS except when you want to check the rejection rate and you can do that easily enough without it being a permanent probe point.

[floridian reefer]

okay i see,

 

 

so when i hook this up, is there something that i can hook to the water line to regulate pressure, then the water goes to a inline tds the the prefilters, then ro, then tds, then di, then tds.

 

 

--------------------

[floridian reefer]

thank you very much for all your help!!! im ready to hook it up now, do you know a place to get just a DI to add to mine? i think im going to keep it with the 3 pre filters and just replace that top carbon with a DI

[krug1313]

bulkreefsupply.com if you want to add a di stage. I find it the easiest and cheapest to change out the di.

[mastahluong]

You will want to measure TDS at 3 places: source water, RO water and RODI water

[AZDesertRat]

If anything just leave the second carbon canister empty or remove it from the bracket until you decide to add the DI. You do not want a horizontal throw away DI, they are low capacity channel or short circuit for lousy treatment and do not las tlong. The cost of ownership over time is many times higher than a refillable vertical and you will never get the same water quality.

 

For DI resins andcartridge no other vendor custom blends all their resins and packages them fresh in vacuum sealed mylar bags for maximum life like Spectrapure, you can find the SilicaBuster in the sales flyer I linked to earlier.

 

Yes you want thre TDS readings but if you have an inline you place it after the RO and after the DI as it only has two probes.

[krug1313]

Bulkreefsupply uses vacuum sealed Mylar bags. AZ I know your a big spectrapure fan but you should give the bulkreef stuff a try. It's really good stuff. The price is deceaving. They could easily charge way more.

[floridian reefer]

If anything just leave the second carbon canister empty or remove it from the bracket until you decide to add the DI. You do not want a horizontal throw away DI, they are low capacity channel or short circuit for lousy treatment and do not las tlong. The cost of ownership over time is many times higher than a refillable vertical and you will never get the same water quality.

 

For DI resins andcartridge no other vendor custom blends all their resins and packages them fresh in vacuum sealed mylar bags for maximum life like Spectrapure, you can find the SilicaBuster in the sales flyer I linked to earlier.

 

Yes you want thre TDS readings but if you have an inline you place it after the RO and after the DI as it only has two probes.

 

thats what i meant about adding a DI, i would add this at the end...

[floridian reefer]

and i see their are different ro membranes for gpd, mine says 50-80 per day so should i go with a 60gpd or A 90GPD? IS IT BETTER TO GO HIGHER?