Advice on rodi

[jordan banks]

I am new to rodi units. I'm going to get one in a few weeks and I plan on getting a mighty mite from air water and ice. I've read good reviews on it. I have three tanks. A 29 gallon solana cardiff, 24 gallon jbj nano cube and a 10 gallon quarintine. Wanting something small and efficient. Please give me some pointers and tips.

 

[jordan banks]

Advice please?

 

[blufin]

Azdesertrat is a resident expert on RO/DI units and can tell you everything you need to know. Maybe he can chime in, or you can send him a pm. Don't go cheap on your unit or you may find yourself having to buy stuff twice. That's what I did and regret it.

 

[AZDesertRat]

You really don't want one of the "portable" type units. They are more expensive to own since the filters do not last as long, are non standard most places and cost more to replace. Besides they really aren't any smaller since they use the same membrane housing and often top bracket, not quite as tall but just as wide and deep and all cobbled together.
A normal, reef quality RO/DI is much better suited for your use, especially with three tanks since you will be making a lot of water. I would suggest something like the 90 GPD refurbished system from Spectrapure for around $140, the 75 GPD Premium from Buckeye Hydro starting at around $140 depending on options or the Optima Vision or Automated from PurelyH2o for around the same.
All use standard 10" replacement filters in low micron ranges so they protect the carbon block, all use some form of the Dow Filmtec 75 GPD RO membrane, all have an inline pressure gauge and all have a full size vertical 20 oz refillable DI canister so it lasts awhile.

 

[Wild1]

AZDR Hi sorry to hijack thread but you obviously are the man to ask. I have a 90 gal. tank with a 30 gal. fuge , what system would you recommend for me? I also have Florida well water. can I still use a RO/DI unit or am I SOL? Thanx in advance CJ

 

[gtbarsi]

I agree that I have not seen any "protoable" RO/DI filters that make sense long term. Go with a standard 75+ GPD full size filter.

Before picking a filter the first thing I would verify if I were you is if you need Chloramine filtration. Most RO/DI filter providers have special additions to address Chloramines. I'm on a well so I did not have to worry about it but before spending a lot of money on a RO/DI filter I would figure out if you need additional filtration for Chloramines. I believe that the filter guys sell a Chloramine test kit, not sure if there are other reliable ways to test, hopefully someone can provide some input.

 

[AZDesertRat]

Chloramines are NOT the issue some vendors lead you to believe.
As long as you have a good 1 micron or less carbon block, protected by an equal sized or smaller sediment filter, and a full size vertical DI with good resin it is no issue at all. With the portables it could be though since they use pretty coarse or even unrated sediment filters and some use GAC granular carbon or coarse carbon blocks and the DI is a small 6-12 oz horizontal throwaway. Don't fall for the catalytic carbon stuff, it is not needed at drinking water levels of chloramines and does not remove chloramines anyway! The carbon ONLY removes the chlorine portion and breaks the bond with the ammonia which is removed by the DI, not the carbon, so good DI is as important if not more important than the carbon.

chopr, the only drawback with domestic or private well systems is they often operate at lower pressures than municipal systems and a RO membrane needs a mini,mum of 40 psi to operate efficiently. If your pressure is 40 psi or more any of the three above is a good choice. If your pressure switch is set at 35 psi like most factory preset switches are then you might require an Aquatec 8800 RO booster pump which runs bewteen $125 and $175 to raise the incoming pressure up to 60-80 psi so the RO is efficient.

 

[gtbarsi]

Not trying to steal the thread here but I wold really appreciate some comments on the filter I have. I'm not listing the manufacturer, just the filter specifications, as I do not want any brand bashing going on. I suspect I may have gone cheaper than I should have with the filter I have. It is a standard size filter with 3 10" replaceable filters, and the RO membrane. I am on a well and my water pressure varies 40-60 psi.

• Purtrex 5 Micron depth sediment filter
• MATRIKX CTO 5 Micron carbon block
• 75 GPD Dow Filmtec Membrane
• Single Deionization(DI) stage with refillable cartridge

I have been thinking that I should make some changes and soon. I was thinking I would move my DI stage to a separate filter bracket and re-plumb the 3 stages I have to filter down to 1 micron before the RO. I have a lot of sediment in my water so would having a 5 micron followed by a 1 micron sediment filters with a 1 micron carbon block be better, or would I be better off with the 5 micron sediment filter followed by a 5 micron carbon block and a 1 micron carbon block? Yet another option would be a 1 micron sediment filter followed by a 5 micron carbon block and a 1 micron carbon block.

I really want to insure that I am getting the best performance out of the RO and DI stages, which a lot of people generally suggest will ware out faster if you do not have everything before them setup optimally.

Any thoughts?

 

[jordan banks]

Does it have to be name brand? I found some 80 gpd on e bay for $130.

 

[AZDesertRat]

With ebay you almost always get what you pay for and its not usually good. There are exceptions but I would look elsewhere as most as drinking wate rquality systems which is very different from reef quality.

gt, with your sediment problems I would look at Spectrapure's 0.2 micron absolute ZetaZorb sediment filter. The advantages are it obviously filters better so protects the carbon block many many times better but also due to its pleated construction it has 10x the surface area so lasts longer and can be carefully rinsed and reused a couple of times before replacing. It also has less headloss so the membrane works better.

I would follow that up with a single 0.5, 0.6 or 1.0 micron carbon block and convert the extra canister into a dual DI with about 20-30 minutes time and only a couple $$. The reason some vendors still go old schol and provide two carbons is they are using coarse sediment filters so the first carbon then acts as a sacrificial filter to protect the second carbon. Waste of money on their part as the better sediment filter and single carbon block has less headloss and lower replacement costs and protects better anyway. The other thing you want to check is your waste ratio, many vendors use a fixed flow restrictor which doesn't work efficiently in every situation sinces everyones water pressure, temperature and TDS is different. If it is not somewhere between 3:1 and 4:1 I would get a capillary tube flow restrictor and trim it according to your exact conditions so the membrane stays well flushed while in use. I would only reduce the waste ratio if you have softened water and lower than normal TDS.

 

[jordan banks]

How about the refurbished unit from spectrapure? What would be the disadvantages of getting that one?

 

[AZDesertRat]

Excellent system.
None unless a warranty is something you feel you need, for the extra $40 or $50 I don't think its worth it. Their reputation as number one in the business for 30 years pretty much speaks for itself. It comes with a specially treated and batch tested high rejection rate 90 GPD membrane, 1 micron sediment filter, 1 micron 12,000 gallon carbon block, 20oz of custom blended SilicaBuster DI resin, inline pressure gauge and capillary tube flow restrictor. If anything at the first 6 month filter replacement I would switch to the better 0.5 micron filter set for only $9 more than the 1 micron versions but that is down the road some.

 

[jordan banks]

Ok thanks a lot that will be my choice then. It looks like a good system to me. Since it's refurbished would it be worth it though?

 

[AZDesertRat]

There really is nothing used about them There may be a scuff or scratch on a housing or bracket so they cannot be sold as new but operationally they are like new with all new filters, membranes and resins.

 

[jordan banks]

Thanks. How much is it to replace the filters, ect yearly?

 

[AZDesertRat]

Economy 1 Micron Pre-Filter Replacement Kit

or the 0.5 upgrades

Standard 0.5 Micron Pre-Filter Replacement Kit

and the DI gets replaced when it is exhausted which could be anywhere between 3 months to a year or more depending on your conditions and how much water you make

SilicaBuster? DI Cartridge - Non-Indicating Standard 10-inch

or you can buy the filters and DI together in a replacement kit and place the new DI in the refrigerator still sealed in its vacuum sealed mylar foil bag until it is needed as indicated with your handheld TDS meter

MPDI System Cartridge Replacement Kit, Standard Twist-On Cap

 

[jordan banks]

And that's all the things that need to be replaced to maintain the unit?

 

[AZDesertRat]

Yes. The membrane should last 7-10 years if you keep up with the sediment and carbon block filters using the same quality replacements or better and you do an annual disinfection of the system as described in the owners manual.

Another thing that helps extend the life of all the filters, membrane and DI is using softened water if you have it available. All membrane manufacturers recommend soft water as it acts like pretreatmnet and does much of the work for the membrane. Its not totally necessary but it makes a huge difference and is great for your house plumbing fixtures and cuts soap usage and scum buildup in the tubs, showers, washing machine and dishwasher.

 

[jordan banks]

Ok thank you very much for the reply.

 

[blufin]

Thanks for chiming in 'Rat. I was hoping you would see this and share your knowledge. Great advice, as usual.

Chopr. I am also on a well system and if yours is like mine, you can change the incoming water pressure at the water softener. I have a pressure tank that regulates the incoming water pressure to the house. It has a rubber bladder on the inside and a pressure gauge on it. The pressure can be raised or lowered depending on your needs. The spectrapure system is the one I chose after talking to 'Rat and it is awesome. My incoming tds is 860 or so, after sediment/carbon and the membrane it is down to 18, then 0 coming out of the maxcap and DI.