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100gpd RODI Installation Instructions

  • install-rodi-hdr_1

Congratulations! Your reef will thank you for providing excellent water quality from now on. This 100gpd 5-stage RO/DI is very easy to install, but if you have any further questions, you can email me any time.

Before you install it, make sure there are no visible signs of damage from shipping. The clear containers (sumps) should be screwed on snugly, and all tubing should be inserted into each fitting. Make sure the tubing is not kinked.


The red tube is the line that supplies water to the RO unit.

The black tube is the drain line for waste water. Simply place this tube in a sink or down a drain and allow the water to flow freely.

The blue tube is your good RO water. 

Many households drink RO water, but the RO/DI water is for reef tanks. This is why the color-changing DI cartridge is mounted separately. Mount the main unit where you like with the DI unit to its right, if possible.





Please note: Saddle Pierce Valve (pictured above) is no longer available as of Sept 2016.

Connecting the unit:

Installing the main unit on the wall securely. Ideally, it should be screwed into a board that is well affixed to studs in the wall.  In this example, the cabinetry had a perfect spot to hang the RO/DI system from. A couple of 1" pan head screws were installed in the 3/4" wood.



The unit was hung on those two screws. And the DI stage was affixed with four screws to the right of the main RO system.


A Tee fitting is installed next between the RO system and the DI stage. Cut the blue tubing as desired to reach the DI stage. See this next picture below. The purpose of this fitting is to capture RO water before the DI stage, either to avoid TDS creep or simply for delicious drinking water. Run the excess blue line from the Tee fitting down, and affix a cut off valve on the end. You can collect RO water in bottles, storing them in the refrigerator until desired for a handy cold drink.



This part is done. Now you need to decide how to connect it to a cold water source. Keep reading.

There are three different ways to connect the red tubing to your water supply

Option 1: Hose bib connection (preferred)

Water Hose bib adaptor - The same threads as your washing machine or garden hose uses, a ¾" female threaded connection can be screwed on to the hose bib, and the red tubing inserted into the fitting. Turn on the water supply and your RO/DI will begin to fill up. To share your washing machine water supply, buy a brass or plastic "Y" adapter from your local hardware store to split to two connections - one for your washing machine, one for your RO/DI. Only use the COLD WATER connection.


Here's an example showing a Y adapter installed on the cold water line behind the washing machine. One side continues to feed cold water to the washing machine, the other side feeds the RO system.  The black hose is the waste line from the RO system, which is inserted about 2' into the drain pipe in the wall that the washing machine uses when it discharges wash or rinse water. You may note this Y adapter also has small cut-off levers to close the feed to either side, which may be handy when changing the filters on the RO system but you don't want to stop water from running to the washing machine.


Option 2: Faucet Diverter

Sink adapter/Faucet Diverter- Remove the current strainer/aerator of your faucet, and screw in the included sink adapter. Press the red tubing over the hose barb fitting, seating it snugly. Turn on the water, and pull out the button to divert water to the RO/DI. Only use COLD WATER.


If the faucet diverter doesn't fit your faucet's threads, this may help:

If the faucet takes a male type aerator (as opposed to the female type aerator found in most kitchen sinks), they will need an adapter for it. I picked it up at home depot for $2. Description on it is:

Standard Male Adapter - 9D
- 15/16" -27 Thread
-Use with 15/16" Female Aerator ID #2B
- Easy to install

It may also necessary to remove the aerating screen before the tee going to the RO system (with the o-ring that is in there; it won't get a bite on the adapter).

Option 3: Angled Stop Valve

Useful under a bath or kitchen sink, this fitting can be installed on the cold water shut off and the threaded / braided hose is screwed onto the threaded end of the fitting. (fitting appearance may vary). Install this fitting, then press the red tubing into the JG collet fully, then tug slightly to test that it is secure.  Open the valve with the blue handle to send water to the RO system.



Permanently installing the drain line (optional)

The black drain tubing can be used with the special drain adapter. It is designed to fit around the PVC or metal drainpipe under a sink up to 1.5" in diameter. Drill a 1/4" hole in the side of the pipe, apply the special gasket material to inner surface of the saddle clamp, align the saddle clamp with the fitting directly over the hole, and tighten the screws until snug. Slide the pastic nut over the end of the black tubing and insert 1" (more and the tubing will be an obstruction in your drain) and tighten. Watch for any leaks. (Images and step by step comments below)

Peel out the center piece of foam, then remove the paper backing.

Apply the foam to the inside of the saddle clamp that has the matching hole. Drill a 1/4" hole in the drain pipe.

Insert the tubing through the nut and saddle clamp, enough to insert into the hole slightly.

Insert the nuts into the slotted holes, then screw the clamp around the drain pipe.

This is what it should look like on your drain. Though hard to see, the 1/4" tubing should barely extend inside the pipe so as not to snag anything (hair, etc) going down the sink's drain.


Now that the system is plumbed to a water source, you can turn the cold water feed and watch it fill up, checking for any leaks. The first hour's worth of RO water should not be used, because it contains the food-grade perservative in the membrane. After 5g of RO water have been made and poured down the drain (or onto some plants in the yard), it is ready to be used, and now you can begin to collect DI water. To be clear: The first hour's worth of production, this water should not pass through the DI stage because it would simply waste DI resin. Let the water come out of the blue tubing you install into the Tee fitting before the DI stage, and keep the valve closed on the tubing coming out of the DI stage.

Included are two blue-handled ball valves, which are your shut offs. Insert the blue tubing coming from the "Tee" and from the DI unit into each one. You can only use one valve at a time when producing either drinking water or RO/DI water. The ball valves will have a John Guest fitting on one end, and is threaded on the other. Remove the blue clip. Press the tubing into the John Guest fitting firmly, then tug slightly to seat it. Replace the blue retaining clip. Ignore the other side with the internal threads, they don't connect to anything in this application. This is where the water comes out when you make RO or RO/DI water.


Note: In the picture above, you can see the electrical outlet beneath the RO system. This customer added a protective plastic cover over that plug to avoid water getting into the outlets. If your RO system hangs over electrical outlets, you should do something similar because when you change filters, you may spill some water. Be safe, and plan ahead to avoid any risk of harm.

So what is this piece for?

The shipping companies occasionally break a fitting from time to time. I've included an extra elbow in every order so that if you find that your system has been damaged, you can quickly fix the problem. It may even be already wrapped with teflon tape, as pictured above. If not, apply a few twists of teflon tape on the replacement fitting before installing it.

Carefully extract the broken half still in the unit, using either one side of some needle-nose pliers or a small flathead screwdriver. Wedge it in gently, and unscrew it from the system. Screw in the new one by hand.

If some tubing is connected to the broken half of the old fitting: Remove the blue clip. Using your fingernail, press the collet against the fitting (what’s left of it) to extract the red tubing.

On the new fitting is a small blue clip. Remove the clip, insert the tubing into the collet firmly. Tug slighly to seat it, and replace the blue retaining clip.

If the collet (the small plastic insert) was cracked or broken during shipping, you can use this spare part. The blue retaining clip may come in handy as well.




What happens next? The unit will fill up with water. When you make RO or RO/DI water, for every gallon you make, you’ll waste 4 gallons of water. This 4:1 ratio is normal, assuming you have average TDS, tepid water temperature and good water pressure.

If the DI chamber doesn’t fill up to the top with water...(Note: A brand new DI cartridge may take as long as 10 to 14 days to stay full all the time. This is normal, and is working properly.) This may occur when making vast amounts of water at once, or when the water supply is very cold during the winter months. Once you close the ball valve, the DI unit will fill to the top, and at that point the system will be off (hissing stops).

You can expect to make approximately 4 gallons of RO/DI water per hour, when optimum conditions exist. (100 gallons per day, divided by 24 hours). In the colder months where I live, it takes 85 minutes for it to make 5 gallons; in the summer months it takes 55 minutes to make the same amount. (Water quality varies from county to county, and state to state.)

When you close the ball valve, there will be a short delay before you hear the unit go silent. This can take about 15 seconds before it shuts off. If it never goes silent, the ASOV (auto shut off valve) or possibly the check valve may need to be replaced. Water is going down the drain. You can check the FAQ section of my site now, and/or contact me so I can get you replacement parts.

If you live in a very cold area, here’s a nice solution to keep your flow rate up even when your water supply is very cold:

Replace the tubing that leads from your cold water pipe to the unit with a 25' long piece. Coil as much of that tubing inside a 5 gallon bucket and fill the bucket up with water so the coils are submerged. Put an aquarium heater in the bucket and set it to 78° F. The heater will keep the bucket water at that temperature, and the water will warm up the water traveling through the tubing to your RO/DI unit. Production rates will jump back to normal.

A comment about quick-connect fittings: These are super easy to use. Insert tubing into the collet of the fitting, pressing firmly. Tug slightly to secure it. If you need to remove the tubing, press the collet against the fitting, and the tubing will be released so you can pull it out. I wish all plumbing was this easy!

The clear canisters (sumps) surrounding the various filters are made of acrylic. They do not bounce, and they are more brittle than PVC. However, I prefer to see the filters for visual inspection. Please handle these gently and they will last for years. Only tighten them hand-tight to avoid breakage. If it holds water, it is tight enough. To loosen the acrylic housings, the included wrench will help. For further details, refer to these instructions.

To test the output water’s quality, a TDS meter is a great tool. The goal is "0". You can also test for chlorine with a kit available at any pool supply. Again, you want it to read "0".

Filters - The sediment filter (first one on the right) and the two carbon filters should be replaced every 6 months. The RO membrane should last you three to five years. The DI cartridge will change in color as it is used up, and its lifespan varies depending on how much water you make and how high the TDS is going into the resin - it could last 4-5 months, or as long as a year. Testing the TDS of the RO water and of the DI water will provide the information as to when the DI needs to be replaced. If the TDS is higher coming out of the DI, the media is fully expended and must be replaced. This page will explain how to change the filters correctly.

If you have any problems, check the RO/DI FAQ page for more details.

If you have any additional questions about your installation or have any needs for additional parts or filters, please email m,e and I will be happy to help you.


Limited Warranty

Melev's Reef makes no claim to the suitability of this product for any specific use.  The end user is solely responsible for determining fitness for a particular use, and for installation.  This product is sold as a component of a custom aquarium installation.

Your product is warranteed to be free of defects for a period of one year from purchase.  We will, at our discretion, repair or replace your product at no charge during this period.  Return shipping is the responsibility of the purchaser.  This warranty does not cover accidental damage, misuse, improper care or alteration, or acts of God, such as floods and earthquakes.  Coverage terminates if the original purchaser sells or otherwise transfers the product.  This warranty excludes claims for incidental or consequential damages, loss of revenue or profits, loss of business, or other financial loss in connection with the warranty problem.  Some jurisdictions do not allow the exclusion of limitation of incidental or consequential damages, so the above limitation or exclusion may not apply to you.  This warranty gives you specific legal rights, and you may also have other rights, which vary from state to state or country to country.

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