Which is more important? RO or DI?

[MizTanks]

Correct me if I'm wrong. First the water goes through the DI resin and then it is pressured through the RO filter?

I know the DI filters out the bigger contaminants and what that doesn't get the RO does?

So can I use a DI filter only or just an RO filter?

[Paulo]

Ro first then it goes thru DI. DI wont do anything for chlorines and smaller stuff. RO IMO is the most important. People have tanks that they have not used either with success. Just depends on their water source.

[CalmSeasQuest]

By far, the best answer is both, but if you HAD to chose - An RO would be the best/only decision. A quality, properly configured RO can remove up ~98% of the TDS in most water with the DI resin removing the remainder. It would not be feasible to use just DI in most scenarios as it would not provide the mechanical and prefiltration of the RO and would exhaust itself almost instantly becoming cost-prohibitive.

We work so hard to limit/remove nutrients and contaminants from our tanks, I shudder at the thought of knowingly introducing them with every gallon of fresh salt or top-off water.

[MizTanks]

Would this unit do?

Reverse Osmosis Water Filter Systems 4 stage 36 GPD | eBay (http://cgi.ebay.com/Reverse-Osmosis-Water-Filter-Systems-4-stage-36-GPD-/140547651041?pt=Small_Kitchen_Appliances_US&hash=item20b94af5e1)

[Heidi]

yes that would do but for like $10 more you can have this...
Aquarium Water | Reverse Osmosis | RODI Water | ReefKeeper Water | Mighty Mite 50GPD with DI Added (http://www.airwaterice.com/product/1MMDI/Mighty-Mite-50GPD-with-DI-Added.html)

RoDi combo for little tanks it has pretty awesome reviews you can get a coupon from them cause they are a sponsor.

$0.02
:big_grin:

[zenpytho]

pure water club 6 stage rodi $109 100 gpd its what i have works great havent had any trouble

[rmalone]

Theoretically you could run only DI and get water spotless....But it would cost an arm and a leg, because you would exhaust the resin so fast. Overall if I had a fish only tank I would only use ro, if I was on city water and had a reef tank, I would consider the same. On a well where the tds is likely 300ppm or more (which is most of south east michigan), ro +di is by far the best bet. Can a person get away with straight up well water? YES but it makes no sense to do so. Water is a small price to pay in the big picture of a reef tank. RODI for all reef tanks using well water just makes good sense both in dollars and reduced headaches. There are a million threads on guys using straight well water with nasty algae issues, yet they test 0 on nitrates and 0 on phosphates (which is another whole issue altogether).

[MizTanks]

yes that would do but for like $10 more you can have this...
Aquarium Water | Reverse Osmosis | RODI Water | ReefKeeper Water | Mighty Mite 50GPD with DI Added (http://www.airwaterice.com/product/1MMDI/Mighty-Mite-50GPD-with-DI-Added.html)

RoDi combo for little tanks it has pretty awesome reviews you can get a coupon from them cause they are a sponsor.

$0.02
:big_grin:

Very sweet unit Heidi~My penny bank is a 1/4 there :)

[AZDesertRat]

Neither RO or DI is particularly effective at removing certain contaminants so it really takes both to do a good job.
RO is only marginally effective at all forms of ammonia including nitrites and nitrates, on the flip side weakly ionized substances like phosphates and silicates are tough for most DI resins.

If you had to choose one it should be a good RO.

I would think twice about the small "portable" RO and RO/DI units, they have major drawbacks. For one they use smaller non standard replacement sediment or prefilters, carbons and DI cartridges. These replacements are harder to find, especially in the low micron ranges reefkeepers prefer for our systems. They also do not last as long due to being smaller and most of all cost more to replace. Try to find a 1 or 0.5 micron prefilter and carbon block for a portable or a 20 oz DI cartridge

Along with that they really are not much if any smaller. They normally use the same top bracket as the full size systems so the footprint is the same, just a few inches shorter so no advantage really. Add to that they do not come with the necessary inline pressure gauge or a TDS meter and most do not have thingsmost of us find useful like an adjustable or capillary tube flow restrictor or a DI bypass valve so you can use RO only water for things like drinking or pet water.

What initially looks like a good deal ends up costing more to operate and often needs upgrades to function as intended. Add up the cost of more frequent replacements a TDS meter and pressure gauge and the cost exceeds the cost of a better full size reef quality system within the first 12 to 18 months. Most of us plan to keep our RO/DI systems for years so the long trerm operating cost is a big issue.

[MizTanks]

I'll be using it for tank water only, at 5g's weekly or biweekly. Does this not make a difference? Oh and it'll be attached to the faucet tap. We have great water here so I'm sure the filters will last longer then usual.

[AZDesertRat]

Regardless of how much or how little water you make, change the prefilter and carbon block at 6 month intervals and disinfect the system at that time. Since these two filters have no effect on TDS you really have no way of know if they "last longer" or not except maybe pressure drop using a pressure gauge and chlorine breakthru using a low range chlorine test kit. Its easier to stick with 6 months as you can see.

Try to make 5-10 gallons of water at a time and use the unit at least every 10-14 days to keep it fresh. Its probably harder on a unit when it is not used enough rather than used frequently, it gives nasties a chance to grow inside them.

[MizTanks]

What a well of information. Thank you DR! Sounds like I'll be drinking RO/DI water too :) drinking fresh water to keep the unit fresh-lol

[Paulo]

Most people do not like the taste of the water that goest thru DI. SO usually they T off water to drink before the DI unit fyi.

[AZDesertRat]

I'd drink RO only rather than RO/DI. It has a bland, blah taste and isn't refreshing.
A simple John Guest tee and a couple ball valves or a three way ball valve will give you the option of RO only or RO/DI depending upon the use. If you were to get a drinking water kit it would look something like the diagram here:

http://www.spectrapure.com/huds/4-STAGE-DWK-RODI-NAG.pdf

Notice the check valve seperating the RO/DI and plain RO sides.

[MizTanks]

OMG am I supposed to be able to read that? lmao! What ever happened to keeping it simple? UGH!

[binford4000]

I'll be using it for tank water only, at 5g's weekly or biweekly. Does this not make a difference? Oh and it'll be attached to the faucet tap. We have great water here so I'm sure the filters will last longer then usual.

Have you tested the water your useing now? When we lived up north our city water was under 80 ppm.Talk to your water department they can give you the levels.It's best to know what your getting befor you try to fix it. I also like the unit Hedi suggested.It's very easy to buy more then you need in r/o di's. 0 to 20 ppm is still 0 to 20 ppm no matter how much you spent on the unit lol

[AZDesertRat]

There is no such thing as getting too much in a RO/DI. You either get one thats reef quality or one that is not.
When you get a reef quality system you get 0 TDS not 0-20 TDS. The advantage of buying a better system is lower overall cost of ownership due to reduced maintenance requirements and filter/DI changes. Yes you may pay a little more upfront but it is returned many times over the life of the system.

80 TDS out of the tap is very good but still not reef quality and it would require a RO/DI to get that to 0 TDS. You could do it with DI alone but the cost of resin replacements or recharging would soon exceed the cost of the reef quality RO/DI in the beginning.

[MizTanks]

I've decided that until I can afford to purchase a unit I'll be pre-treating my makeup/top off water using Marc Weiss: Phosphate+Silicate Magnet. Not a fix for sure but it's something. And it wont leach.

[CalmSeasQuest]

I've decided that until I can afford to purchase a unit I'll be pre-treating my makeup/top off water using Marc Weiss: Phosphate+Silicate Magnet. Not a fix for sure but it's something. And it wont leach.

Marc Weiss: Phosphate+Silicate Magnet (http://www.marcweissco.com/freshwater_marine/phosphate_silicate/phosphate_silicate.html) - INGREDIENTS: Iron, calcium, magnesium, selenium, molygdenum, copper. Derived from ferment of: Sugar cane molasses, vitamins, yeasts

I'd do so research on Marc Weiss products Jamie - they do not have the best rep. Personally, based on the contents, I don't think I would use it in my tank. The active ingredient is likely GFO - the rest looks like snake oil to me.

The goal is 0 TDS - NOTHING but H20 and certainly not derivatives from fermented sugar cane. I also would have a problem trusting a firm that adds copper to a compound used in a reef tank when they can't spell Molybdenum. ;)

[MizTanks]

Ok I'm beyond frustration here! I need to treat my water with something. If not this then what? Suggestions? And please don't say an RO/DI unit.

[CalmSeasQuest]

Ok I'm beyond frustration here! I need to treat my water with something. If not this then what? Suggestions? And please don't say an RO/DI unit.

First.....relax :)

Best option - not allowed to say ;)

Alternatives - Friend or neighbor with a RO, local store that sells RO (i.e. supermarket) look in the phone book, often water treatment companies sell RO water.

The best long term option is the unmentionable.

Have you tested your water? - TDS? Although not a best practice, there are many that have thriving reef systems using tap or well water. I was amazed to learn the Tropicorium supports their entire operation using many thousands of untreated Detroit city water weekly. If you're not having nutrient/silica/phosphate problems (i.e. algea, cyano, diatoms...) then just keep doing what you're doing and save your nickels for an unmentionable ;)

[MizTanks]

First.....relax :)

Best option - not allowed to say ;)

Alternatives - Friend or neighbor with a RO, local store that sells RO (i.e. supermarket) look in the phone book, often water treatment companies sell RO water.

The best long term option is the unmentionable.

Have you tested your water? - TDS? Although not a best practice, there are many that have thriving reef systems using tap or well water. I was amazed to learn the Tropicorium supports their entire operation using many thousands of untreated Detroit city water weekly. If you're not having nutrient/silica/phosphate problems (i.e. algea, cyano, diatoms...) then just keep doing what you're doing and save your nickels for an RO/DI.
You said it!!! then just keep doing what you're doing and save your nickels for an RO/DI. Lol

[CalmSeasQuest]

You said it!!! then just keep doing what you're doing and save your nickels for an RO/DI. Lol

Nope - look again ;)

[binford4000]

There is no such thing as getting too much in a RO/DI. You either get one thats reef quality or one that is not.
When you get a reef quality system you get 0 TDS not 0-20 TDS. The advantage of buying a better system is lower overall cost of ownership due to reduced maintenance requirements and filter/DI changes. Yes you may pay a little more upfront but it is returned many times over the life of the system.

80 TDS out of the tap is very good but still not reef quality and it would require a RO/DI to get that to 0 TDS. You could do it with DI alone but the cost of resin replacements or recharging would soon exceed the cost of the reef quality RO/DI in the beginning.

20 tds is still reef quality water,really it's a 29 gal tank she has and it will take years for a filter and di change even on a cheap unit.Matching the unit to the systems needs is only practicle.If she has 80 tds out of the tap she can run it thru just about any filter system and get quality water.

[AZDesertRat]

Unfortunately most Marc Weiss products are snake oil and have a horrible reputation in the industry.

There is no substitute for (unmentionable), plain and simple.

If you cannot afford one then find a trusted source. Of course (unmentionable) is the best choice but you will probably only find it at a LFS as other hobbies don't use it much. Second choice is distilled water in the gallon jugs at the grocery, it should be very close to 0 TDS too. Third choice would be RO only from a manned or staffed Water & Ice type store which usually have knowledgable staff and will have a TDS or conductivity meter to show you what you are buying beforehand. I have had very positive results at the stores when you tell them what you are using it for, they seem very proud of their product and bend over backwards to please you, especially if you have a few photos of your reef! Its RO only but usually very high quality and only 25 cents a gallon .
Fourth choice would be gallon jugs of RO from the grocery as long as they do not say remineralized which means it has TDS added back in for taste.
Last choice would be a vending machine since they are not regulated by health agencies and you are at the mercy of the vendor who is treating it for taste not for a reef so quality can be all over the place.

[AZDesertRat]

20 TDS is nowhere near reef quality water, who told you that? Get real.
The problem with TDS is you have no idwa what the TDS consists of, it could be phosphates, silicates, nitrates, copper etc. You don't have a clue and hobbyist grade test kits do not work well on ultrapure water so don't suggest it.

Filters get changed every 6 months on a RO/DI no matter how much water you make. Extending the changes increases the likelyhood of bacteria, virus and algae growth inside the housings and filters since we are providing the perfect environment for them to multiply and grow with warm still water, clear housings and absence of a residual disinfectant since we removed it with carbon.

[jimsflies]

I guess the question I have for Jamie is, what problems are you having with your tank? If its algae/phosphates then you might be able to band aid the situation with some phosban in a filter sock tucked inside of your HOB.

If there isn't a problem and you want an RO/DI to just do better...then I wouldn't add any other chemicals of suspicious content to the water. If it's not broke don't fix it approach.

[binford4000]

20 TDS is nowhere near reef quality water, who told you that? Get real.
The problem with TDS is you have no idwa what the TDS consists of, it could be phosphates, silicates, nitrates, copper etc. You don't have a clue and hobbyist grade test kits do not work well on ultrapure water so don't suggest it.

Filters get changed every 6 months on a RO/DI no matter how much water you make. Extending the changes increases the likelyhood of bacteria, virus and algae growth inside the housings and filters since we are providing the perfect environment for them to multiply and grow with warm still water, clear housings and absence of a residual disinfectant since we removed it with carbon.

WOW,I never change my filters tell my TDS is above 40,and even that's extreme in allot of peoples opinons/To change filters by calendar dates regardless of if it needs to be changed is a very extreme regiment for sure.The filter company's love you for sure.Me I'll pass and use real measurments to decied when to change em.Each their own.Gotta go with Jims reply "if ain't broke don't fix it!"

Anyome out there know what the TDS or real ocean water is?? 20 parts per millon is dirty?

[jimsflies]

I think its a good point that TDS can consist of anything...one person's TDS of 20 if it is all phosphate is a bigger deal than someone else who has a 40 TDS and it is all calcium. But in the interest of safe advice, we have to assume the worst case.

TDS is just a number...and we can say 0 TDS will always be good whereas higher levels are going to be hit or miss.

@binford...you are on DWSD (detroit) water. The Trop is also on DWSD water...so it is no surprise to me that you can get by with 40 TDS. The Trop for example uses straight tap.

[AZDesertRat]

OK, a little schooling is in order.
First off prefilters and carbons have very little to absolutely nothing to do with TDS. Think about it, they are in the 10, 5, 1 or maybe 0.5 micron ranges. Thats suspended solids.
TDS or dissolved solids are in the 0.0001 micron range, many many times smaller than those are capable of removing.
You CANNOT use TDS as a gauge or measure on when to change prefilters and carbons, theye serve two different purposes. TSS (sediment, particulates, colloidal materials, silt etc) is removed by the prefilter and carbon along with chlorine and some VOCs. They are there solely to protect the expensive RO membrane whose job it is to remove 90-98% of the TDS with the DI resin getting the rest.

What you need to understand with TDS is if any is present, its possible you have more than you know. Weakly ionized substances like nitrates, phosphates and silicates are just tha, they contain very weakly chaged ions so do not measure well on a TDS meter. You can have high silicates and phosphates in the treated water and not even know it. Another very very important point is DI resins starte releasing these weakly ionized substances even BEFORE it is exhausted. That means when you start seeing 1 or 2 TDS up for 0 TDS you are starting to release contaminants the DI resin has attracted over time and put it back in the treated RO/DI water. Since they are weakly ionized you may not see them and again they will not test well on a TDS meter or hobbyist grade test kits since it is ultrapure water, but rest assured they are present if they were in the tap water.

You always change prefilters and carbon blocks every 6 bmonths like clockwork. At this same time it is advised you disinfect the system with household bleach following the directions I have posted many times to reduce the chances of virus and bacteria growth. You change the RO membrane when it is no longer cost effective to keep changing DI resins frequently and you change the DI resin when it is anyting other than 0 TDS on a regular basis.

[binford4000]

OK, a little schooling is in order.
First off prefilters and carbons have very little to absolutely nothing to do with TDS. Think about it, they are in the 10, 5, 1 or maybe 0.5 micron ranges. Thats suspended solids.
TDS or dissolved solids are in the 0.0001 micron range, many many times smaller than those are capable of removing.
You CANNOT use TDS as a gauge or measure on when to change prefilters and carbons, theye serve two different purposes. TSS (sediment, particulates, colloidal materials, silt etc) is removed by the prefilter and carbon along with chlorine and some VOCs. They are there solely to protect the expensive RO membrane whose job it is to remove 90-98% of the TDS with the DI resin getting the rest.

What you need to understand with TDS is if any is present, its possible you have more than you know. Weakly ionized substances like nitrates, phosphates and silicates are just tha, they contain very weakly chaged ions so do not measure well on a TDS meter. You can have high silicates and phosphates in the treated water and not even know it. Another very very important point is DI resins starte releasing these weakly ionized substances even BEFORE it is exhausted. That means when you start seeing 1 or 2 TDS up for 0 TDS you are starting to release contaminants the DI resin has attracted over time and put it back in the treated RO/DI water. Since they are weakly ionized you may not see them and again they will not test well on a TDS meter or hobbyist grade test kits since it is ultrapure water, but rest assured they are present if they were in the tap water.

You always change prefilters and carbon blocks every 6 bmonths like clockwork. At this same time it is advised you disinfect the system with household bleach following the directions I have posted many times to reduce the chances of virus and bacteria growth. You change the RO membrane when it is no longer cost effective to keep changing DI resins frequently and you change the DI resin when it is anyting other than 0 TDS on a regular basis.

great info :snorkel:

[MizTanks]

This is what I'm dealing with. I'm seeing it only on the tank back (in pix) all the glass and on the powerheads. I don't know whether it's Dino's or Diatoms. I just scraped the back yesterday~I took this pix today. So it came back overnight.


http://i1080.photobucket.com/albums/j338/NanaReefer/IMG_0234.jpg

http://i1080.photobucket.com/albums/j338/NanaReefer/IMG_0237.jpg

[AZDesertRat]

What you are seeing is normal in unmature systems and the reason why I paint my backgrounds black rather than blue. I don't clean the back and with black you don't see it, with blue like my sons tanks have it looks nasty.

A reef will continue to evolve and go through algae stages for up to a year or more. I remember when I first set up my present system 7.5 years ago, it went through every stage you can imagine before settling down. I have never used anything but RO/DI from a well maintained Spectrapure MaxCap so I know none of it was water quality related yet I still had it all and in every color of the rainbow. I went through hair algae, diatom blooms, dinos, bubble algae, cotton candy algae, red slime, green slime, black slime, you name it I had it at one time or another and chalk it up to the maturation process.

[MizTanks]

Guess what? The lights are playing tricks on yeah-my back is black-lol

Well I'll keep saving my pennies for the, you known what. And while I'm waiting I'll just keep scraping :)

Thank you so much DR! You've been a well of information and a great support. I've gone from not knowing jack about RO/DI to knowing more then jack-lol