# [Wet Thumb Forum]-RO units and plant tanks?



## Robert Hudson (Feb 5, 2004)

Under what circumstances would someone use an RO system with a freshwater plant tank? Whats the difference between a unit that is RO and one that is RO/DI?


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## Robert Hudson (Feb 5, 2004)

Under what circumstances would someone use an RO system with a freshwater plant tank? Whats the difference between a unit that is RO and one that is RO/DI?


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## nino (Oct 2, 2004)

Hi Robert,

I use RO unit for my discus tank since my GH is at 300ppm. 

RO unit remove contaminants and mineral by pushing the water thru permeable membrane and DI use ion exchange method to remove contaminants. Using both in series can filter out 99.9% mineral and contaminants. But lately, many companies come out with DI unit only. This gets quite popular because it takes less space and no water is wasted. But some hardcored reefkeepers still prefer RO/DI unit together. 

Another reason people use RO unit before DI is also to avoid any premature PO4 or silicate leaching by DI unit. If the resin bed is exhausted, DI unit tends to leach these 2 contaminants.

I could understand if some people choose to mix RO water with their tap. I myself would do it if I'm persistance to keep certain plants. We'd discussed this hard water vs plant topic in another forum and many have similar problem keeping certain plants in hard water (Rotala Macrandra as one of them). 

Are you considering to use RO/DI unit?


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## gpodio (Feb 4, 2004)

Hi Robert,

I use RO/DI mostly to have more control over water parameters. I like to experiment with things so being able to control hardness and other contaminants makes things a little easier. Since I stopped using tap water, certain plants have indeed changed a little however the effectes have been minimal on it's own. The biggest difference I've noticed is with my fish, they are far healthier now and spawning with ease compared to before. My RO filter removes most everything but some nitrates and phosphates do get through, after the DI filter however the water is very pure. Lately my TDS has been around 4-5 after both filters. DI on it's own can do the same thing however it's lifespan would be so short that you'd have to change the filter too often without pre-filtering the water through an RO membrane first. Other advantage are good drinking water and tasteless ice cubes 

Considering the money we put into our hobby, $100 for an RO/DI filter was a pretty good investment I feel.

Regards
Giancarlo Podio


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## Robert Hudson (Feb 5, 2004)

No, but I have picked up a line to sell, and I wanted to have a clearer idea of the application. You put minerals back into the water for the plants correct?


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## nino (Oct 2, 2004)

You have to if you use 100% RO water. Many including me prefer to mix them with tap water. Since people who use this have very high mineral/traces contents in their tap, no mineral additive is necessary. 

There are different type of additives. Another reason is to add buffering capacity since RO/DI water has KH close to 0. Some is PO4 based buffer and should be avoided for planted tank use.

If you're planning to carry these units, also check on DI unit (not the regular tap water filter from Petco). It's getting popular in Europe also since it's cheaper to run, smaller and no water waste. I believe Kent is also making them. If it really works as it's advertised, I would prefer that than regular RO unit.


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## Robert Hudson (Feb 5, 2004)

Here is what I have

2 STAGE STINGRAY $ 99.00 
AQUARIUM REVERSE OSMOSIS SYSTEM 50 GPD 


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3 STAGE DOLPHIN $ 149.00 
AQUARIUM REVERSE OSMOSIS SYSTEM 50 GPD


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3 stage Dolphin 100 GPD $ 169.00 
3 STAGE DOLPHIN AQUARIUM REVERSE OSMOSIS SYSTEM 100 GPD 


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4 stage RO/DI Barracuda $ 219.00 

4 STAGE RO/DI BARRACUDA REEF TANK REVERSE OSMOSIS DI 50 GPD


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## gpodio (Feb 4, 2004)

> quote:
> 
> Originally posted by Robert H:
> No, but I have picked up a line to sell, and I wanted to have a clearer idea of the application. You put minerals back into the water for the plants correct?


I use Seachem Equilibrium and baking soda for my main tank. In another tank I add nothing, I use 100% RO/DI in that one. Yet another tank gest Equilibrium however no baking soda... that's where the fun is  you get to experiment a lot more.

Regards
Giancarlo Podio


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## nino (Oct 2, 2004)

Good pricing especially the 100gpd one.


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## Robert Hudson (Feb 5, 2004)

whats a good GPD?


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## nino (Oct 2, 2004)

Before the 100 or 120gpd came out. The common choices were 25 and 50gpd (I use 50 gpd). In the last few years, the standard on some brands went up to 35 and 60 gpd. Then all the 3 digits gpd started to come out. Most people will go for 50-60gpd nowadays since the price difference is not too big compares to 25-35gpd. Many would like to own 100-120gpd but usually the price is almost double (around $270-330). If you can sell those under $200, I believe it's gonna attract people to buy. I really don't get it though. How come your 100gpd can be that cheap. The price difference to 50gpd should be a lot more and I'm talking about 50%-100% more.


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## Robert Hudson (Feb 5, 2004)

WEll I guess I found a competitive manufacturer! They pretty much set the price. Spread the word in the reef forums!


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## gpodio (Feb 4, 2004)

> quote:
> 
> How come your 100gpd can be that cheap. The price difference to 50gpd should be a lot more and I'm talking about 50%-100% more.


You'd be surprised that the only difference between a lower and higher GPD is just the membrane type and flow restrictor. Prices used to be high between them because of the extra "luxury" of having more GPD, but in reality we're talking about a couple dollars difference between the two. A 25GPD membrane costs $10-15 less than a 100GPD membrane and the flow restrictor, although different for the two, costs the same. You can buy a 25GPD RO unit and change the membrane to a 100GPD, change the flow restrictor and you're done. The rest of the unit is the same.

Robert, I don't know if your units have an optional water container or not but I find it a huge help. It allows you to have a certain amount of water available at any time seeing the "live" rate of filtration is so slow. It's been a huge time saver for me compared to waiting for the water to be filtered each time I needed to fill a gallon jug for storage.

Giancarlo Podio


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## Robert Hudson (Feb 5, 2004)

They have storage containers, is that what you mean? For the benefit of others, how about explaining what a GPD is?


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## nino (Oct 2, 2004)

Giancarlo, are you talking about a container where the RO output goes to, like a large bucket? If so, many people build their own using rubbermaid garbage can with a float valve.

Rob, GPD is the approximate quantity of water produced by the RO unit. This can vary between cities or even houses. It depends on water pressure and mineral contents of the tap water. The harder the water, the less RO water it can produce and also the shorter the membrane life.


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## gpodio (Feb 4, 2004)

GPD=Gallons per day. It's really just a measure of the RO membrane and the flow restrictor, once everything is hooked up the flow is less. Like ninob said, your water pressure will make the biggest difference, I'm not sure at what pressure the GPD rating is taken. Water temperature also makes a difference, the colder the water the slower it gets filtered.

Regarding the container, it's a pressurised water container, it will automatically fill itself up and provide a certain amount of gallons available under pressure, great for drinking or sink faucets but also useful for filling water containers quickly. My filter is under the sink so I don't have a lot of room to make my own rubbermaid container. Here's a picture of it:










It's a real luxury, I still fill gallon jugs between water changes but like this I can fill 3 gallons in seconds. An hour or so later and I can get another 3..... You know how many times I flooded the kitchen by forgetting that I have the water open slowly trickling into a jug after the container has run out?  I actually plan to get another one and have 6 gallons available at a time.

Giancarlo Podio


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## imported_Nathan (Feb 17, 2004)

Other questions.

-Clear or White canisters?

Clear offers the user to see when the filters change colors and help to gauge when to change. White or colored ones are lower in cost.

-DI?

Is it included, is the media color changing to show when exhausted?

-If DI is incl, is there a take off for RO only?

Since there is argument of the safety of drinking DI treated water a takeoff allows the user to draw only RO treated product.

Cartridge size?

What size are the filters, by that I mean what is the level of filtration. A person on well water would want a 10 micron initial filter then a 5micron carbon and 1 micron before going to RO Membrane. While a city water user would want to have 2 carbons to insure complete chlorine removal. Chlorine kills the membrane. Starting with a very fine such and 1 micron filter will only clog it fast. 

-What tap(s) is(are) included?

Not everyone wants to pierce a water line. Some may have a hose type connection available, such as splitting off the Washing Machine feed. 

-Float Valve

My product water is saved in a 50gal drum. When filled the valve closes and the excess pressure turns off the input feed via a pressure switch.

-Pressure Level indicator

By monitoring the running pressure level I can see when Membrane needs to be flushed. 

-Membrane flush

Flipping a valve on the unit allows on to flush the RO membrane increasing lifespan. 

Will you also carry replacement cartridges, membranes and DI resin as well? What about parts ? You may want to take a gander at some of the sites that specialize in RO units such as AirWaterIce and Buckeye Field Supply, both are the touted highly on the reef forums for great product and service. 

There is lots to consider when picking up a new line. Marketing to the reef folks could open a realm of possibilities since they also use CO2 for Ca reactors and need most of the parts and pieces plants folks use. However they are very quick to cry foul and pull no punches in reporting slips in service on a highly read forum. 

Good Luck with the new line


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## gpodio (Feb 4, 2004)

> quote:
> 
> Originally posted by Nathan:
> Other questions.
> ...


I opted for the cheaper white canisters and the use of a TDS meter to know when the filters need replacing. Quite honestly looking at color change doesn't always give you a precise indication, perhaps not very important for planted tanks but if you also need to use the water for a reef then TDS readings are your best solution.

Giancarlo Podio


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