RO/DI

[Kelly]

I have a question which feels like a stupid thing to ask, but I really don't understand the RO/DI. I'm not so interested in what it does--I understand at a basic level that it purifies the water and is necessary for a successful reef tank. Right now, I'm having a local company deliver RO/purified water in 5 gallon containers. It's working pretty well so far, and for simplicity's sake, I don't mind keeping up that process. It is a little expensive week after week, but again, it is very simple. Obviously, I'm new to this hobby and learning as I go. I also have a pro helping me, but I'm trying to learn more and more on my own. I guess what I'm curious about is whether or not continuing using the commercial purified water is ok, or if I should go ahead and make the investment in an RO/DI system. If so, is it difficult to hook up? Where would I hook it up? Is it time consuming to "make" the water? I'd welcome any thoughts. Thanks

Kelly

[Jon Lazar]

Many people, especially those with larger tanks, find an RO/DI unit more convenient and cheaper in the long run than buying RO water.

 

My RO/DI connects directly to my sump and comes on whenever the water level drops a certain amount. I have multiple backups to prevent overfilling, but most people frown on this approach as too dangerous, and instead store their RO/DI water in a separate container and then pump water from the storage contrainer to the sump.

 

If you find buying water more convenient and affordable, that's probably a good fit. You can have a great reef tank without an RO/DI unit.

[hypertech]

The DI makes it purer. The biggest reason for switching is cost. It will cost you pennies (20 gallons of water and a small amount of consumables in the filter) to make that 5 gallons.

 

It's not that much work if it's set up right. Turn it on for a couple hours and let it do it's thing.

[Pete Touhey]

One thing I quickly learned is that you can't underestimate the value of purified water in this hobby. You don't necessarily need DI (my TDS is 160ppm+ in and 4ppm out on just RO), but it doesn't hurt. You might see if your pro has a TDS meter, and test the commercial water. If the readings are low, you have a relatively small tank, and 5 gallons covers your top off needs and water change needs, than you might be better to stick with your water service. However, if the TDS reading is high, you are getting a lot of algae, or 5 gallons isn't quite meeting your needs you might want to think about an RO or RO/DI unit. Remember to factor in the cost of the disposable filter replacements 1 to 2 times a year depending on (Sediment, 1 or 2 Activated Carbon, and possibly a DI). As for hooking it up, most come with a "garden hose" attachment that fits the threads on most laundry sink faucets. I have a 30 gallon trash can next to the Laundry sink I keep mine in (takes about 12 hours to fill). RO filters come are sold at various gallons per day rates. If you do get one spend a few bucks more to get a larger filter than you think you need. You don't want to wait all day to get 5 gallons, and it can come in handy in a tank emergency.

 

 

[zoozilla]

It's not very difficult to hook up. Most of the RODI units come with fittings which allow you to hook it up to any existing faucet with a hose adapter. Also, if you or someone you know is handy with plumbing you can also install it directly to the water pipe under sink using a self-piercing saddle valve. Personally, I have it hooked up to the laundry room sink.

[Origami]

RO/DI water is cleaned of many impurities that we don't want in our tank, and some that we do. Examples of stuff we don't want: Phosphates, nitrates, ammonia, chlorine and/or chloramine, bromine etc. Examples of stuff that we want (but get removed anyway): Alkalinity (carbonates and bicarbonates) and calcium. One advantage is that it gives us a known starting place, so that when we put together our salt mix, we can count on the quality and the content over time.

 

Whether or not its more affordable depends upon your usage and your cost of buying the stuff. (I'm not considering convenience.) How much do you pay for 5 gallons anyway?

 

In my case, I probably endure overall around 25 gallons of evaporation a week with an additional 35 gallons a week in water changes. That's 60 gallons of RO/DI consumed per week, or around 3,100 gallons per year. Filters and such cost me, on average, around $114 per year. That's counting changing out my RO membrane once every 2 years, and all of my other stages every 6 months (sediment, catalytic carbon, 2 carbon blocks, and refilling my DI bed). That works out to (not counting the setup cost of an RO/DI system) around 3.7 cents per gallon.

 

Your mileage may vary.

 

Kelly, you should edit your location in your profile to show where you're from. I'm sure that one of our members would be happy to show you how their RO/DI system is set up. You have many options. Mine is hard-wired into my plumbing and production is completely automated. Others may hook their systems in using a faucet connector and use it only when needed. Even if you hardwire it into your plumbing, it's really not all that difficult to do.

[bluefunelement]

I have a question which feels like a stupid thing to ask, but I really don't understand the RO/DI. I'm not so interested in what it does--I understand at a basic level that it purifies the water and is necessary for a successful reef tank.

 

 

So instead of the how here's the why:

It's not the impurities that go into your tank each water change but the buildup of impurities that happens during top off replacement. And it's not so simple as if your tap water or RO water is low TDS then you should be fine. As evaporation takes out only pure water it leaves behind all the impurities. So if you put in 2 gallons of 20 TDS water top off water each week then in one month it's added up to 80 TDS added- now your water change would also have 20 TDS so not accounting for carbon, skimming, etc you will always be losing ground.

Analogy could be that you buy 1 trunk full of groceries each week with lots of packaging and only eat the edible stuff. But you only take 1/2 trunk full of waste to the dump each month. What is your house gonna look like in several months? Buy a goat.

 

Now you don't check TDS in your tank and it doesn't even mean that all the dissolved solids are bad but so many of our municipalities have inconsistent water quality that you are taking a huge risk.

I used to use DI filtered well water (useless) for a FOWLR tank but had to switch to RODI when I added corals.