What RODI unit should I get?

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crister13

Aquarium Advice Addict
Joined
Aug 2, 2011
Messages
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Location
Princeton, NJ
I found RODI unit for 65$ and it says it starts puriying under 35 PSI and I dont know what my sinks are. Should I just get it?
 
It also says i would have to replace the DI every 500-1000 gallons. Could I just wash it out or something? I HAVE NO IDEA HOW THESE WORK!!!!! HAHA
 
Any RODI will make water at low psi, but with high waste. Are you US? A booster pump will save a lot of water if you have low pressure
 
What do u mean with high waste? Wont it just be useless then? Yes im in the US. I think my sink is pretty normal.
 
what is meant by high waste is that instead of having close to a 1:1 ratio you'll be at like 3-1 or possibly worse... also it runs fairly slowly. I have 20 lbs of pressure, it takes me about 30 hrs to fill my 18 gallon tank while the waste tank (also 18 gal) fills in about 8-10hrs.

a booster can be had for around 80 if you look around, i dont have the link currently for some reason. I will be getting one, but the filter works without it.
 
For every one gallon of filtered water you get, 3 to 5 gallons of water will pass out of the filters waste tube. That water is filtered through the first few stages and then moves through the RO membrane. I use it for my FW tank, others fill their washing machines, or water the lawn with it. It is good water, but higher in TDS than your tap.

DI resin takes the water that is filtered through the RO membrane and brings the TDS to 0. Once it is depleted, it is cleaned out of the cannister and new resin is packed in.
 
Having been in this business for going on 15 years, and because much of that time we have had a focus on RODI systems and supplies for the marine aquaculture trade, my advice to you is ...

Watch out!

Any system retailing for $65 is probably not worth having. I would look elsewhere, especially if you are unfamiliar with these systems and don't feel like you are making an educted purchase.

Could we make a $65 system? Sure. But I wouldn't be able to sleep at night if I sold it to someone.

Russ
 
Here are some things to look for in a good system for this hobby:

No more than 4 stages (sediment, carbon, RO, DI) unless you have specific water quality issues you want to address
Standard-sized prefilters, membrane, and DI cartridge
Brand name, high-rejection membrane
Specifications provided for each stage
Pressure gauge after the prefilters and before the membrane
Thermometer
TDS meter (handheld or in-line)
DI bypass
Vertical DI stage
Refillable DI cartridge
Aluminum bracket
Quick connect fittings
No water from pressurized storage container delivered to DI
Flush valve
Clear housings
High-quality instructions written in clear English
Customer support before, during, and after your purchase
A vendor involved in your hobby

Russ
 
Having been in this business for going on 15 years, and because much of that time we have had a focus on RODI systems and supplies for the marine aquaculture trade, my advice to you is ...

Watch out!

Any system retailing for $65 is probably not worth having. I would look elsewhere, especially if you are unfamiliar with these systems and don't feel like you are making an educted purchase.

Could we make a $65 system? Sure. But I wouldn't be able to sleep at night if I sold it to someone.

Russ

Since you are in the business, what if you get 0ppm readings from the $65 unit. Isn't that the purpose of the unit, or what we are trying to achieve? Are there other things we should be aware of, even if getting these results? TIA
 
I'm also curious what someone says who sells these things for a living. I'm also getting 0 readings on nitrates, phosphates and TDS. My tap TDS is over 250 too. :)

I think for the price and availability that the $65 unit is a good entry level unit. I haven't had a single issue with mine and have no algae problems so I think the unit is doing it's job.
 
Thats what i have from mine granted i didnt get a tds meter, but the lfs can tell you where youre at
 
Since you are in the business, what if you get 0ppm readings from the $65 unit. Isn't that the purpose of the unit, or what we are trying to achieve? Are there other things we should be aware of, even if getting these results? TIA


We could for instance make a system that consists of (only) an inline DI resin cartridge that would produce 0 TDS water.

So the question really is - How well does the system perform over time, and how does the cost of operation/maintenance compare to other systems.

Without knowing specifically which system you have, I can't really provide any detailed comments. My comments are based on hundreds of similar conversations we've had through the years. I don't want to bash any vendor, so if you'll PM be the brand name and model, I'd be happy to talk with you in detail offline.

Who knows - maybe they have new technology in their $65 system that is superior to everything else out there (very, very unlikely).

Russ
 
I think ALOT of people on here would like to know what you think of this unit

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I purchased mine about 6 months ago for an initial $70 say. I have a clear DI chamber the newer ones like listed above now have a solid DI chamber. I recently started to get TDS readings so I ordered the replacement filters for $28? or so. Planning on installing them next time I need water.

Now keep in mind I don't drink this water, it's entirely for the tanks I have. I also needed the portability aspect as I have NO room for an in plumbed system anywhere. This is also a four stage system if that matters.
 
Definitely following along since I also bought a filter from this same company for fairly cheap price.
 
I'll make some comments about these small systems in general, stage by stage


A better system would have:

  • a 10" x 2.5" sediment filter with a pore size of 1 micron
  • a 10" x 2.5" carbon block (NOT gac) with a pore size of 0.5 micron. The filter in this system is designed to be placed between a pressure tank and a faucet - not to be used to filter feedwater. It has a capacity of about 2,000 gallons - a good block has a capacity 10x that, and costs about the same.
  • a pressure gauge.
  • a 10" x 2.5" vertical, refillable DI stage.
  • well-writen instructions
  • Horizontal DI cartridges are a fundamental design flaw - so if you've bought one of these systems, unclip the DI filter and orient it vertically with bottom-up flow.
  • As pictured, the system has a 100 gpd membrane, but a flow restrictor for a 50 gpd membrane. You'll generate less waste water than the membrane manufacturer recommends, and shorten the life of the membrane
It is what it is. In this case, if you paid $65 for it, I think you got what you paid for. This system might be ok if you have a very small aquarium - like an 8 gallon pico.

Replacement filters are about the same price as you'd pay for standard sized filters, but they have much lower capacity - so the cost of ownership will be higher. You'll end up replacing them more often. Also - especially the way they have that system configured, switch to a higher rejection membrane.
 
they claim to use standard size filters so could we use the system with their filters until its time to replace, then use higher quality filters? my di filter is refillable i was planning on using those color changing nuclear grade ones next- are they worth the cash?

Also which way is bottom up for the di? so the water enters the bottom is that right?
 
Yes - water should flow up from the bottom to the top through those DI carts. Make sure the DI cart is packed tightly and is completely full.

Russ
 
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