RO/DI filter question

[Despairodyne]

I have a RO/DI unit called an AquaFx. It has a sediment filter, two canisters labeled chloramine, an RO filter and two DI canisters.

Two questions:

1) The DI resin is a deep purple color with a little bit of golden color in the
first DI canister. Can I assume that the resin will turn golden as it gets used up?

2) The media in the chloramine sections looks to be carbon in a is a plastic tube. What kind of carbon should I use as a replacement. Is there anything special about chloramine removal.

I bought the thing about 12 years ago to make water for some very fussy orchids. The output water still measures a 0 TDS with my recently calibrated meter but none of the filter media has ever been replaced. I expect to be making a lot of water in the near future so I want to have the replacement media on hand.

Thanks

 

[Jetlinkin]

Answer to number 1) Yes. When you have the color changing DI resin, it will turn a golden color when exhausted. You can also keep measuring the output with your TDS meter. When you get a reading on the TDS, it is time to replace. I use both, and I find that when it is all golden, I get a reading of 1-2 ppm TDS.

Answer to number 2) I am not familiar with the chloramine filters, as I do not have chloramine in my water, so I do not use that filter. I just use a sediment filter in the first stage, then two carbon filters in the next two stages. I do know that you only need the special chloramine filter if you have chloramines in your water. Your local water authority will be able to answer this for you. I get my water report every quarter from the city, and I check what they are putting in. I do know from talking to them, chloramine is not often used. It is needed for special cases, but the majority of municipal waters systems use chlorine, which is different.

 

[Randy Holmes-Farley]

The chloramine filter is a carbon block (mostly removes chloramine and chlorine), which all RO/DI should have. You should buy a carbon block, not refillable GAC. You need not buy a special choramine filter, IMO, unless the circumstances are special. My water company uses chloramine and a normal carbon block is adequate here. I surveyed a lot of people for my chloramine article, and a normal carbon block is typically adequate.

Unless you want to measure chlorine in the RO waste, I'd replace the carbon block now since there is no other easy way to know if it is working except to monitor chlorine/chloramine. Often they clog before going bad, but a 12 year old block may not have adequate capacity remaining.

 

[Despairodyne]

Thanks Jetlinked.


Randy,

The carbon canisters contain refillable tubes but from what you say, I expect there is a solid block replacement I can put in their place.

I will be testing everything. I started my professional career as an analytical chemist. Back when it was all about HPLC and trying to transmute copper into NSF grants.

I do hate color tests though. Maybe I can find a mass spectrometer on eBay.

Thanks again guys.

 

[Randy Holmes-Farley]

A solid carbon block is a more normal RO/DI filter choice. I didn't even know refillable ones were commercially available.

The chlorine tests are pretty straightforward.

I discuss such issues in these articles:

Reverse Osmosis/Deionization Systems to Purify Tap Water for Reef Aquaria
http://reefkeeping.com/issues/2005-05/rhf/index.htm

Chloramine and the Reef Aquarium
http://reefkeeping.com/issues/2003-1...ture/index.htm

 

[Buckeye Hydro]

The refillable chloramine carts are fairly standard now-a-days. When intended to treat chloramine reputable dealers fill them with CGAC, rather than standard GAC.

A 12-yr old used CGAC cartridge is undoubtedly kaput. Refill both or replace each with a Chloraguard Block.

Russ

 

[Despairodyne]

Thanks Russ,

I found the CGAC media for my refillable carts.

S-

 

[Buckeye Hydro]

I didn't even know refillable ones were commercially available.

We see these in rodi systems for the aquarium market typically from "auction site" vendors - often on systems with many stages - some of which are commonly configured incorrectly. Often these are drinking water systems assembled overseas, designed for very slow membranes (e.g. 12 gpd), brought into the US, and then the vendor uses higher capacity membranes and starts scabbing on other filter stages.

The worse use of gac as a prefilter is the mini RO or mini RODI systems where small non-refillable Taste and Odor filters (essentially a small tube containing gac) designed to treat (dechlorinated) RO water between a bladder tank and a faucet are used as prefilters.

Russ