RODI questions

[travis32]

There's been some discussion on source water using RODI vs. RO and softners.

This will probably show my ignorance and naivity, but, here's my understanding.

Softners remove hevy metals (rust, iron, etc) from the water and replace those metals with salt. If the softened water is plumbed into the RO system, the RO unit then removes the salt that was put there by the softner. Thus leaving just water. The RO system has a multiple stage filters in addition to the membrane. 2 precarbon filters and one post carbon filter + the RO membrane.

Now, my question is what is the difference between that process and RODI..

What kind of flow can one get with an RODI? I can get up to around 10 to 15gallons in 24 hours with my current RO system. What does a typical (relatively low end) RODI unit provide?

I spent around $1800 for the RO and softner system (obviously for more reasons than the aquarium) but, in my ignorance felt this was a good time to do a SW aquarium since I finally have RO water. Something I never had before.

Do RODI units need to be plumbed or can they be ran from a faucet?

 

[mcoomer]

I can't speak to the use of softened water but I can tell you that my Spectrapure is rated at 60 gallons per day. I run mine from a faucet in the garage with a pressure regulator on it so that I can use a solenoid and float switches to turn it on and off as needed to keep my tank topped off and my freshwater reservoir filled. However you decide to plumb it just make sure that you can disconnect it in case of a leak or for ease of service when you're replacing filters.

Mike

 

[Ken Good]

I started mine running from a faucet, but quickly plumbed it in and have never looked back.

 

[Gtstricky]

I am not sure about your question but I think you are over thinking this.

THe goal of RO/DI is to have 0 TDS in your water. If you have an RO system buy a simple TDS meter and check it. My guess is you will need to add DI. It should be a simple add on to your system (less then $50). Just put a tee in your RO out put and on one side add a DI canaster. Use that water for your tank.

Yes RO/DI systems can be run off of a faucet.

Look at www.thefilterguys.biz for the parts you need.

 

[travis32]

My RO system fills a 3.5 gallon preassurized "holding tank" and is a very slow flow.

 

[Chiefsurfer]

well your system might be slow because it is running into a pressurized tank. RO membranes need a lot of pressure to get good water passage through the filter.

I am not exactly sure what a softener does, so I can't speak on that, but I will tell you a bit about a RO/DI system. Usually it goes through a screen filter first. This is usually 5, 2, 1, etc. micron-filter. This takes particulate out, like pieces of calcium that build up and flow through the system. Then on to a carbon filter, which is designed to take out chlorine. From there it usually goes to a charcoal filter(if you have one, some only have a single carbon filter) to filter out more chlorine and chloramine. Then it goes on to the RO membrane. In a perfect world, your water out of the RO membrane will be 0TDS. Problem is that after the first few gallons, it's usually not TOTALLY zero TDS. Usually somewhere between 2-5. Once your membrane starts putting out 5+ it's usually on it's way out. The DI part is AFTER the RO membrane. All this is, is a canister, just like your carbon filter canisters, but it is filled with these teeny tiny balls that are called DI Resin. These balls basically pick up the slack of the RO membrane. they convert that 2-5tds water down to absolute zero TDS. Your system seems VERY slow, and might want to talk to a house plumbing personnel about a pressure booster pump to boost the pressure into the RO membrane, as it should increase your outflow at the same time. If you do boost the outflow, you can definitely use just a DI canister T'd off your regular line to make tank water.

Only Problem I see is with the reservoir. If your pressurized tank isn't huge, at 10-15 galoons per 24 hours, It will take you a year to fill your tank, and probably 5 days to make a batch of water for water-changes.

Most systems created for tanks can run up to 75gpd easily, and DI resin will never restrict that more.

 

[btb72]

mine runs at 150gpd

 

[Tomaric]

Travis RODI water is not recommended for human consumption. If your current RO system is under your sink (like mine) leave it be and install a seperate RODI system. You really don't want your freinds and family drinking the DI water.

 

[lordofthereef]

There is actually nothing wrong with drinking DI water. Frankly that is just a myth started God knows where.

 

[reefman30]

I saw your post on another thread saying you had a culligan system. Those home systems are not made to make alot of water. They usually make about 10 gallons a day at most. Adding a DI chamber after the RO will not slow down water production.

There is actually nothing wrong with drinking DI water. Frankly that is just a myth started God knows where.

+1

 

[bertoni]

The only issue with drinking RO/DI water is making sure that there's no bacteria in it. The filter and storage container need to be maintained properly at drinking water safety levels. The same caution applies to RO, too.

 

[travis32]

Well, I talked to the culligan person today. The cold tap water is at 620 ppm. The water from my RO system, is 25 ppm. I've talked to others here and they tell me that RO is fine for Reef water.

So, I guess, I'm thoroughly confused. LOL. I realize 6 people will have 7 different opinions, but, I have to look to the ocean and wonder if the ocean is any purer....

 

[reefman30]

In a perfect world, your water out of the RO membrane will be 0TDS. Problem is that after the first few gallons, it's usually not TOTALLY zero TDS. Usually somewhere between 2-5. Once your membrane starts putting out 5+ it's usually on it's way out.
.

This made me chuckle. :lmao: My tap water has TDS so high that 20ppm coming out of the RO is good. And from the original posters post on another thread it sounds like he either lives in west texas like me or has just as bad water.

 

[travis32]

Good point reefman30. I think mentioned this somewhere else or earlier, but, the water burnt out 2 heating elements and 2 thermostats on a brand new water heater in under 1 year. BRAND NEW! That's when we decided to go with the softner. They said the softner will damage the water heater also, but, it will take 3 to 5 years to destroy it instead of only 1.. It's scary when SALT is the least damaging option!!!

But the 25 ppm is AFTER the water is softened, and the RO membrane is less than 1 year old.

Culligan said that with the softner the RO membrane will easily last 6 to 7 years. Without the softner, they said I'd be lucky if it lasted 1 year with my water.

620 ppm down to 25 ppm. I feel is good. I don't know if a Deionizer would get it any better. Our city is considered to have the worst water.. Well the river that we get the water from is consistant muddy color. So, yeah.

 

[bertoni]

For some people, tap water is fine for reef tanks. How safe your water is depends on what's in that 25 ppm of TDS. If there's a lot of copper, or some day the water company tosses an anticorrosive into the pipes, your corals and perhaps fish will die. On the other hand, the TDS could be calcium, magnesium, and perhaps some chloride, and your system will never have a problem.

 

[travis32]

Thanks bertoni. That's something I can understand and makes sense to me.

 

[Chiefsurfer]

^+100

TDS is not a definitive answer to whether water is good or not. The only way to know FOR SURE that it is NOT bad for your tank is to get it to absolute zero, then add what you want. That is why we do it. If 599 ot of 600ppm are calcium, magnesium, or any other trace elements that are safe for us to have in our systems, then absolutely fine using straight tap. If 599 of those same 600ppm are copper, chlorine, chloramine, steel(rust), lead, etc. Then it is entirely unusable.

If you have 680, and are getting 25 out of your RO, CONGRATS. I WOULD suggest using DI resin tho. DI resin will catch anything. Theoretically you could just run your water straight from your tap through the carbon and micron filters, then on to DI resin and get zero out. If your incoming is 680, don't expect that DI resin to last more than 10 gallons though. Although 25 is pretty high, and you will go through a lot of DI resin, I still reccomend it. Unless you can figure out what those 25ppm ARE.

 

[Buckeye Hydro]

Fun fact to know and tell:

Guess what is in a water softener...
Cation DI resin.

It is a type of cation resin that can be recharged with sodium rather than acid - so that's the purpose of all the salt you add to your softener.

When the resin is exposed to certain cations (e.g., calcium and magnesium - i.e., "hardness"), it grabs the cations and releases cations it holds less strongly (sodium).

Russ