build your own rodi

sign guy

sign guy

Active Member
Seeing how everybody is always looking for purer water, I thought it would be a good idea to point out a few ways to save some money and have some fun by building your rodi unit yourself. I also plan to to mention a few good brands of parts and whole units that would be best for our tanks.
Before we get into how to build one its best to explain what each part is and its purpose in the filter. A rodi unit filters tap water with reverse osmosis deionized filter (rodi) There are 4 stages in a normal rodi unit. they are in order sediment (sed), carbon reverse osmosis and deionize (di). The sed. carbon and DI's are in ten inch clear cans. The ro is contained in a pressure vessel that looks like a pvc pipe with end caps and mounted on top of a bracket. the three cans are mounted to the bottom of the bracket
This is a pic of a very good brand the kent maxima HI-S 35 gpd unit
 
trippkid

trippkid

Active Member
No problem, just getting on your case.
I know this can be a very big subject, I'm sure you'll run into the character limit and have to post a couple of times. Just don't forget to save what you've typed, I hate it when I type a huge post, then the character limit kicks in, and I usually have to re-type or get mad and give up.
Matt
 
sign guy

sign guy

Active Member
ok in the pic above the the sed filter is all the way on the left the carbon is in the middle and the di is the last can on the right. The ro membrane is in the white pressure vessel on top. As said before (but to elaborate) the water comes into the front of the sed can and travel down the center of the filter and is pushed through the filters walls and travels back up the can outside of the filter and then out the back of the cap. it dose this with the carbon as well, once it exits the carbon it flows into the the pressure vessel. All ro membranes I have seen are wraped in plastic and have a gasket around it. the gasket seals the membane to the inside walls of the pressure vessel thus forcing the water to travel thrugh the membrane. After the water passes through the membrane it enters the exit line in the pressure vessel. where the exit line connects to the ro is normally where the flow restrictor is placed. this restrictor sits inside the line its self and slows the water down so the water can travel at the same speed as the ro membrane is built to handle. this is where rejected water comes from, water that is not allowed trough the ro will back up in the membrane itself and be forced out your rejected line. Therefore all rejected water has gone through the sed filter and carbon and is fairly clean. Any way to get back on track the water that is allowed through the flow restrictor is sent to the DI can in the same fasion as the sed and carbon fiter.
this is a pic of the flow restrictors inside of your lines the color of each restrictor just lets you know what gpd restrictor you have
 
sign guy

sign guy

Active Member
first off here is what you need
3 ten inch clear canisters with 1/4 ports
a pressure vessel (make sure if you want a pressure gauge to look for the pre drilled 1/8 inch fpt hole
a flow restrictor of your prefrence
a maching gpd ro membrane (I highly recamend a dow flimtec)
A sed filter (A 5 micron is a good medium)
a carbon filter ( highly recamend Matrix+c20 hard to find though)
and a DI (look for 100% mixed bed and color changing)
A bracket
and 1/4 inch poly tubing
 
sign guy

sign guy

Active Member
I showed a pic of a flow restrictor earlier but I have seen some beeing sold in its own housing like the one in this pic (its sitting just beside the T valve). If this is the cace just hook it up in the same place, just after the membrane but befor the di
 
sign guy

sign guy

Active Member
If your looking to save a few bucks Id try and see if you can get the cans at a hardware store, just make sure that they have screwholes in the tops of the lids so they can mount to a bracket. I bought all my fittings from one of the big hardware stores, I do prefer the slip fittings so they are easier to work with. as far as brackets go you can buy them yourself online or find a local metal shop and have one bent up for you like I did. I used aluminum .063 gauge
 
sign guy

sign guy

Active Member
allright what do I need to alaborate on I think there could be some confusion (due to the dumb butt who started this thread) so let me know
 
wattsupdoc

wattsupdoc

Active Member
How much $$$$ did this cost? My Ro has s different thingy on it. It uses 4 lines after the RO. I forget what its called, but you'rs doesnt need one? How does the reject water leave the RO if the restrictor is after the RO???? I'm a bigger dummy.
 
sign guy

sign guy

Active Member
Originally Posted by wattsupdoc
How much $$$$ did this cost? My Ro has s different thingy on it. It uses 4 lines after the RO. I forget what its called, but you'rs doesnt need one? How does the reject water leave the RO if the restrictor is after the RO???? I'm a bigger dummy.

quite unclear on the thingy doc as far as monny goes Im not sure I have a lot of extras on mine
I attaching three pics and im not sure in what order thell apper so let me explain.
1 it sonds like the 4 hoses that come out of your unit is an automatic shutoff atachment you dont have to have it if you dont plan on getting a floatvalve or a drinking water addon in the future. one of the pics is a shutoff attacment for the end of a pressure vessel
2 pic 2 is a drawn cut away of a ro membrane I hpe dispite my bad art skills it can clarify my bad explnation skills. basicly the restrictor only allows its set amount of water to pass through. so lets say your membrane and restrictor is a 35 gpd, and your pumping 90gpd. sience your restrictor only allows 35 gallons to pass and the membrane can hold only so much water at a time the remaing 55 gallons never make it into the ro filter therfore are forced out yout rejected line. the gasket in the pic shows that water is not allowed past a certen point preventing water from skiping the ro
3 you asked about price and pic three will explain why its kinda hard to give a price. just to save you the trubble from counting its a 7 stage. I will go through my files and pull some old invoices and see what I can do about giving an estimated price


 
mscarpena

mscarpena

Member
Just a comment. If you build your own are you really saving $$$. I got mine for like $170.00(seachem pinnicale) shipped and after you buy all the pvc, lines, pressure gauge, fittings, and filters you will add up to that. Just buy one all you are really paying for are the filters anyway.
 
dogstar

dogstar

Active Member
The flow restrictor should be in the waste/rejected water line...this is what keeps the proper amount of presure maintained on the membrane.
 
sign guy

sign guy

Active Member
Originally Posted by Dogstar
The flow restrictor should be in the waste/rejected water line...this is what keeps the proper amount of presure maintained on the membrane.
ooh very good dog. your right, I just dubbel checked mine and it is on the rejected line. that blows my understanding out of the water on that. Could you explain a little more
 
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