RODI unit - which part do I need to replace?

[Seafan]

Hi, I have AquaFX Mark I C5 5 stage RODI unit that's less than 2 years old. I use the RO water for drinking, and RODI water for my 55g tank that I do water change about once a month. Recently the drinking water started to taste funny. I'm wondering if I need to replace any of the filters or media. Here is a picture of it:



Appearantly the media in the first unit turned yellow. What is it and do I need to replace it to improve the RO water quality?

thanks,

Jason

[Unresistible Blue]

Seafan - need a little info to answer your question.

Your unit has 2 DI housings, right?

You say the unit is less than 2 years old. Have the filters all been in place for about 2 years, or have you changed them before?

When you say the first cartridge has turned yellow - are you talking about the far right hand cartridge?

Blue

[Seafan]

Your unit has 2 DI housings, right?

yes.

You say the unit is less than 2 years old. Have the filters all been in place for about 2 years, or have you changed them before?

haven't changed anything

When you say the first cartridge has turned yellow - are you talking about the far right hand cartridge?

yes, see picture.

[Unresistible Blue]

That picture helps. What does your built in TDS meter tell you? How much less than 2 years old is it? How much flow have you put through it?

I think AquaFx has replaced your unit with what they call the Mako 5 stage model, which uses two mixed bed, color-indicating DI units.

Assuming you've had a "typical" amount of water run through the unit over the ~2 year period, and by the look of the unit, I would say without a doubt your far right hand filter (sediment) is more than shot. The next filter to the left, the white one, is your carbon block filter. Depending upon which carbon block cartridge Aquafx installed in your unit when it was new, I'd guess you are approaching 4 times its expected lifespan/chlorine capacity. If they used the Matrikx+1 (like they do in the Mako model), you may be ok here because it has a chlorine capacity of 20,000 gallons. If you're not sure, replace it. Its not expensive and without it you'll kill your RO membrane. On second thought, I'd replaace it no matter what. Surely to prefilter fabric around the carbon block is full.

If your carbon block is shot, and has been for some time, my guess is that the ro membrane has been destroyed by the chlorine. Do you have a 50 gpd or 100 gpd unit?

Again assuming a typical rate of water treatment, I'd expect your right hand DI cartridge was shot 6 to 18 months ago. It doesn't look like its changed color however. Did your unit come with color indicating DI resin? When/if it went, and with the state of the sediment and carbon cartridges, and if the RO membrane is bad too, I'd expect you went through the second (far left) resin cartridge very very quickly.

So, based upon some assumptions and what you've told me here, sorry to break the news but my best guess is that you need to replace the sediment cart, the carbon cart, both DI carts, and maybe the RO membrane as well.

Don't be too worried if this is the case however. You can replace all those items for a fraction of what you paid for the unit originally. The RO membrane (that goes in the smaller horizontal housing on top) will be the most expensive item.

Is your TDS meter shot too? Can you test it against another tds meter?

HTH,
Blue

[reefhead]

hey Blue,


how much does a new unit like that go for?

[Unresistible Blue]

AquaFx sells their 5 stage Mako for $279 (50 gpd) and $319 (100 gpd). You can find them cheaper and more expensive than this as well.

[Seafan]

thanks Blue. I have the 50 gpd model, I use the RO part often for drinking water, and RO-DI for top-off water and water change for my 55g and 20g, so maybe once a month, not heavy use.

I'll definitely change the sediment and carbon filter as you suggested. The DI part is a little confusing to me - I'm not sure if the resins are supposed to change color, if they do, can I see it from that picture? also the inline monitor still indicates the end product of RODI water is "normal" - does that mean the DI part is still working to compensate the RO part?

and if I need to change the DI, do I need to change the cartridge, the resins, or both? when I purchase "DI replacement cartridge" from the vendor, are they supposed to include the resins, or do I need to buy them separately?

thanks!

[Unresistible Blue]

I'll definitely change the sediment and carbon filter as you suggested.

Good. Can't go wrong here.

The DI part is a little confusing to me - I'm not sure if the resins are supposed to change color, if they do, can I see it from that picture?

It all depends upon your resin. You may have color-indicating resin (i.e., color changing resin), or you may not. You'll have no doubt when a color indicating resin changes color. A dark resin like yours might turn a light sand color.

also the inline monitor still indicates the end product of RODI water is "normal" - does that mean the DI part is still working to compensate the RO part?

What its telling you is that the produced water is below its "trigger" level, whatever that is. Or the monitor isn't working. Check it against another meter. Check your tap water, post RO water, and your post DI water and see what you get. That will tell you what’s working and what’s not.

and if I need to change the DI, do I need to change the cartridge, the resins, or both? when I purchase "DI replacement cartridge" from the vendor, are they supposed to include the resins, or do I need to buy them separately?

Most retailers will sell you a "DI Cartridge." It will be a sealed cartridge filled with DI resin.

If you can find a source, your $ ahead to get a filled refillable cartridge instead. When its exhausted, you dump the resin and buy a refill. You'll save money this route. I've attached a picture of a refillable cartridge.

Blue

[Seafan]

Just bought a Hanna handheld TDS meter, and the tap water reads 170 ppm, RO reads 5 ppm, and RO-DI water reads 1 ppm. are these normal readings?

[Unresistible Blue]

Those sound like readings well withoin the "normal" range.

Blue

[Seafan]

Originally posted by Seafan
Just bought a Hanna handheld TDS meter, and the tap water reads 170 ppm, RO reads 5 ppm, and RO-DI water reads 1 ppm. are these normal readings?

does that mean my carbon block, RO membrane, and both DI are still good? I got the replacement parts, but I wonder if I should replace them based on visual inspection, or TDS meter?

[Unresistible Blue]

Your carbon block filter really doesn't affect the TDS, so no telling, based upon your TDS reading, if your carbon block needs to be replaced. You can go by a 6-month rule of thumb, or look at the chlorine capacity of the carbon block filter and change it according to that.

Looks like your RO membrane is doing what its supposed to do, in terms of TDS.

Also looks like your DI resin is working fine.

Use your meter to monitor the outputs periodically.

Blue