Looking into Buying RODI system

[Sdoutreefer]

Researching RODI systems and don’t totally know what unit I should be buying. I’d like to go with a 5-stage, but curious if that many stages will be enough. The water at the source is relatively hard, I do know that. Is there somewhere online, or someone on this forum that can point me towards what unit I should be buying? Will a 5-stage be plenty? Or is it really worth going with a 6 or 7 stage?

 

[JumboShrimp]

Speed (gallons per hour) is one factor-- if you are just doing occasional water changes and occasional top-offs on a 32 gallon BioCube, that will be a lot different than say having a 300 gallon display tank, or multiple tanks including frequent water changes to keep ammonia down on quarantine tanks. Of course, if you are looking at a BRS 5 stage, almost anything you don't get at first can be added later. But that's a more expensive route in the long run. (I'm talking about additional canisters, a second membrane, etc.). You will have to consider whether you want a booster pump, as well. How many gallons will your salt mixing station holding tanks be, if you are planning to have a station?

 

[C_AWOL]

Based on your build thread, a 5 stage will be more than enough since 6+ stages that I've seen are typically just additional DI stages which won't offer much benefit as long as you regularly change your di resin as needed.

Next factor that might matter is 75gpd vs 150+gpd. Higher gpd rates require higher water pressure and commonly decrease rejection rate which will increase DI resin consumption. Fortunately it's not difficult to upgrade a unit you purchase so settling with a 75gpd unit with a tank size like yours is fine and could even work well for larger systems with adequate water storage options and a float valve.

 

[Sdoutreefer]

Speed (gallons per hour) is one factor-- if you are just doing occasional water changes and occasional top-offs on a 32 gallon BioCube, that will be a lot different than say having a 300 gallon display tank, or multiple tanks including frequent water changes to keep ammonia down on quarantine tanks. Of course, if you are looking at a BRS 5 stage, almost anything you don't get at first can be added later. But that's a more expensive route in the long run. (I'm talking about additional canisters, a second membrane, etc.). You will have to consider whether you want a booster pump, as well. How many gallons will your salt mixing station holding tanks be, if you are planning to have a station?

Thank you for your input! I will most likely only hold a MAX of 20 gallons at a time. This will purely be for top offs and bi-weekly water changes.

Based on your build thread, a 5 stage will be more than enough since 6+ stages that I've seen are typically just additional DI stages which won't offer much benefit as long as you regularly change your di resin as needed.

Next factor that might matter is 75gpd vs 150+gpd. Higher gpd rates require higher water pressure and commonly decrease rejection rate which will increase DI resin consumption. Fortunately it's not difficult to upgrade a unit you purchase so settling with a 75gpd unit with a tank size like yours is fine and could even work well for larger systems with adequate water storage options and a float valve.

I believe 75gpd will be more than enough for what I'm planning to use it for. I am planning to make a small fill station off a hose bib in the backyard, assuming setup and tear down is easy enough with a hose bib connection. I just wasn't sure if I needed to be evaluating the water source, and then deciding what stage system I needed.

 

[rtparty]

Additional DI stages are never bad.

Do you know if your water is treated with chlorine or chloramines? If you’re not sure, get a 5 stage for the second carbon block just in case it’s chloramines.

There is real benefit going to a 7 stage though if you need it. By separating the resins into cation, anion, and mixed you only replace what is being depleted. Saves money in the long run. For example, my source water is high in silicates so I go through anion resin faster. In a mixed resin it will only deplete the anion while the cation is fine. Yet, to replace the anion resin I have to throw the whole thing away. With my 7 stage, I just throw away the anion portion while cation and mixed bed are still in great condition.

 

[Ryan - Serious Reefs]

Keep in mind that this isn't a forever decision. You can always add a can to either side down the road. After messing with these for a decade plus this is my take but 5 stage is probably the sweet spot of cost and performance for most people.

3 Stage RO: ~ 50 times Better than tap water. Outside of easy to treat disinfectants, the biggest issue with tap water is often sky high calcium and alkalinity. To a moderate degree, nitrate and phosphate. The RO only system is going to remove a vast majority of the disinfectant, calcium , alkalinity, nitrate and phosphate. There will be some left over but once diluted in the tank it is typically not a big deal.

4 Stage RO/DI: Somewhat better than RO only. The DI's biggest advantage is just peace of mind. You got the last 2% and using ~lab quality water. I'd use this if I had some nasty contaminants like chloramines, copper, arsenic or ammonia gas. Reality is most of us have one of these so RODI has become the defacto solution for purifying freshwater for reef tanks.

5 Stage RO/DI: Dual carbon is what I recommend to my friends as longs it fits in their budget. Why two carbon blocks? Carbon blocks are far from 100% effective and let more disinfectant through the longer they are are on. Running two in series means the first dramatically reduces the disinfectant the second has to deal with and becomes very efficient. Typical blocks are near useless on chloramines as well.

6 Stage RO/2DI: Only real value for me is I don't have to monitor the exhaustion point of the DI resin and avoid the purge.

7 Stage RO/3DI: The Cation > Anion > Mixed Bed resin configuration does produce higher quality water. Mostly because the different stages have major pH differences that change the form of some contaminants like Ammonia or Silica and makes them easier to remove. I think that value is negligible unless you nerd out on water quality. The biggest value comes from more efficient use of resin. In a typical mixed bed the Anion resin runs out way before the cation does so you throw away perfectly good cation resin. When you separate them in the 7 stage configuration you only change the one that needs it. For me that is typically 5:1 meaning for every 5 anion cartridges I only use one cation. Another benefit is resin swaps and overall maintenance is reduce and why I typicality use 7 stages.

This is a summery of decades worth of researching, building, using and creating videos on RO/DI. Hopefully it is helpful :)

 

[Sdoutreefer]

Additional DI stages are never bad.

Do you know if your water is treated with chlorine or chloramines? If you’re not sure, get a 5 stage for the second carbon block just in case it’s chloramines.

There is real benefit going to a 7 stage though if you need it. By separating the resins into cation, anion, and mixed you only replace what is being depleted. Saves money in the long run. For example, my source water is high in silicates so I go through anion resin faster. In a mixed resin it will only deplete the anion while the cation is fine. Yet, to replace the anion resin I have to throw the whole thing away. With my 7 stage, I just throw away the anion portion while cation and mixed bed are still in great condition.

I honestly have no clue what all is in my water source. Is there somehow to look online?

 

[KStatefan]

I honestly have no clue what all is in my water source. Is there somehow to look online?

It should be available find that then contact Russ @Buckeye Hydro had have him put together system for your needs and water supply.

 

[Sdoutreefer]

Keep in mind that this isn't a forever decision. You can always add a can to either side down the road. After messing with these for a decade plus this is my take but 5 stage is probably the sweet spot of cost and performance for most people.

3 Stage RO: ~ 50 times Better than tap water. Outside of easy to treat disinfectants, the biggest issue with tap water is often sky high calcium and alkalinity. To a moderate degree, nitrate and phosphate. The RO only system is going to remove a vast majority of the disinfectant, calcium , alkalinity, nitrate and phosphate. There will be some left over but once diluted in the tank it is typically not a big deal.

4 Stage RO/DI: Somewhat better than RO only. The DI's biggest advantage is just peace of mind. You got the last 2% and using ~lab quality water. I'd use this if I had some nasty contaminants like chloramines, copper, arsenic or ammonia gas. Reality is most of us have one of these so RODI has become the defacto solution for purifying freshwater for reef tanks.

5 Stage RO/DI: Dual carbon is what I recommend to my friends as longs it fits in their budget. Why two carbon blocks? Carbon blocks are far from 100% effective and let more disinfectant through the longer they are are on. Running two in series means the first dramatically reduces the disinfectant the second has to deal with and becomes very efficient. Typical blocks are near useless on chloramines as well.

6 Stage RO/2DI: Only real value for me is I don't have to monitor the exhaustion point of the DI resin and avoid the purge.

7 Stage RO/3DI: The Cation > Anion > Mixed Bed resin configuration does produce higher quality water. Mostly because the different stages have major pH differences that change the form of some contaminants like Ammonia or Silica and makes them easier to remove. I think that value is negligible unless you nerd out on water quality. The biggest value comes from more efficient use of resin. In a typical mixed bed the Anion resin runs out way before the cation does so you throw away perfectly good cation resin. When you separate them in the 7 stage configuration you only change the one that needs it. For me that is typically 5:1 meaning for every 5 anion cartridges I only use one cation. Another benefit is resin swaps and overall maintenance is reduce and why I typicality use 7 stages.

This is a summery of decades worth of researching, building, using and creating videos on RO/DI. Hopefully it is helpful :)

Thanks Ryan!!

I'm leaning towards the 5 stage as it seems to fit my budget at this point in time, but just wanted to make sure I wasn't going to be wishing I had the 7-stage. From what I'm told, my water source is relatively clean. I just wish I knew of somehow to backcheck that!

 

[Ryan - Serious Reefs]

I honestly have no clue what all is in my water source. Is there somehow to look online?

Your city will have a water report but it very rarely is particularly useful to reefers. Can test on your own.

TDS: Low TDS is a good indicator of moderate alkalinity and calcium in your water. High TDS often means you have a lot of calcium and alkalinity in the water. That might sound good but it isn't. If your tap water is 10DKH and your salt is 9 DKH the net result will be 19DKH saltwater.

Nutrients, Ammonia, Phosphate, Nitrate: Most people have these kits, if yours works in freshwater use it directly. if it is a saltwater only kit use it on freshly mixed saltwater. You are not looking for minor readings but something that is grossly off.

Trace Elements: Things like copper and zink from the pipes and municipal distribution system which is often 50-100 Years old can be tested with test kits or ICP report.

Disinfectant: Total and free chlorine test strip will tell you if you have chlorine or chloramines.

It's been my experience that greater than 80% of reefers will have a material issue with one or more of these. Probably why reefers don't bother and RODI has become a staple of modern reefing.

 

[Ryan - Serious Reefs]

Thanks Ryan!!

I'm leaning towards the 5 stage as it seems to fit my budget at this point in time, but just wanted to make sure I wasn't going to be wishing I had the 7-stage. From what I'm told, my water source is relatively clean. I just wish I knew of somehow to backcheck that!

No problem. If you ever want a 7 stage down the road all you need to do is add a couple RO cans to the system. It's not a forever decision :)

 

[landlubber]

Thanks Ryan!!

I'm leaning towards the 5 stage as it seems to fit my budget at this point in time, but just wanted to make sure I wasn't going to be wishing I had the 7-stage. From what I'm told, my water source is relatively clean. I just wish I knew of somehow to backcheck that!

Personally i'd contact your local LFS if there is one available in your community. Most have experience with and can offer advice on which systems best suits the water available in your area.

 

[Lasse]

The best way to be sure that there is no chloramines left in the RO water is to add around 5 ml (a tea spoon) vitamin C into each 25 G of RO water (Vitamin C = ascorbic acid)

IMO - which type of RO you need is depended of your tap water.

I did one ICP test on my tap water before I decided which type I would use. Its important that you take the sample in your tap you are going to use - the pipes in the house can affect the values.

I use a rather simple 4 stage 100 G/H (sediment, active carbon, RO membra and a mixed bed) The lab I use for ICP test also test my RO water and when I get readings of Si - I change the mixed bed. My ingoing water have around 463 µg/L Silicon. My mixed bed lasts about 8-10 months before it needs to be replaced. All other important substances is always non detectable. My TDS run around 1-2 ppm out from the RODI and around 100 - 150 into it

Instead of putting in money (if your ingoing tap water is rather good - as mine) fancy multistep system - I would put the money in a fast system of two reasons

1) With time - you will be very tired to wait for your RO water to fill up
2) The speed is total depended of the pressure in your tap water - most system need around 4 bar in order to give what they say. If you have a lower pressure it will give less IME a faster membran does not require higher water pressure - stated capacity are usually at the same pressure - i.e a 75 G at 4 bar will give half of a 150 G at the same pressure.

If you have very much calcium and magnesium in the ingoing water - your membran will last for a longer time if you have a zeolite filter as first step. This filter you can regenerate with a saturated salt solution how many time you want. I have a very low ingoing Ca - around 22.8 mg/L and I make around 30 G RODI water every third week. My membrans last for at least 1 - 1.5 years

Sincerely Lasse

 

[Quietman]

I went with a 5 stage initially. I have very hard water with high TDS. Worked very well but I was burning through mixed resin very quickly. After a year or two I added the separate cation/anion/mixed and reduced my DI resin consumption from once mixed every 6 weeks to an anion once every 5 or 6 months. I'm glad I did it that way though because it's an easy add on and who wants to spend money if they don't need to. Turned out I needed to, but that's how it goes.

 

[Freenow54]

I still stand by my zero waste made by Watts. Did add a DI filter, and after some good advice a UV light made a big difference. I don't understand why everyone is concerned about speed. I have to say that it is really slow. #% gallons in about one and a half days. But great filter system, and they are

readily available from Amazon. I am on town water treated out of Lake Erie this is the primary filter after 6 months. Pretty Scary