help with ro/di

[sps1-2-b]

I have a Captive Purity ro/di filter, and for some reason my tds readings are strange. After the tfc, sediment, and carbon filters my tds reads 005. Then after the DI cartridge my tds reads 014. I have the dual in-line tds meter from marine depot. Is my DI resin leaking something that is adding to the tds? Is this even possible? All 3 filters plus the tfc membrane were replaced 4 mos ago, and the tds meter is 3 mos old. Thanks.

[an411]

could be that the Resin needs to be replaced. I know that people say that filters for the ro/di last up to 6 months. I think that this varies on the amount of water that you make. Seeing that you have 240 total water volume I am sure that you do pretty large water changes and its summer so you probably have more evaporation therefore making more water which in turn means shorter filter life.

[crvz]

was the TDS resin replaced 4 months ago? I'm not sure if that's clear. Id try to replace that as a first solution.

[fatdaddy]

If you have a dual TDS meter, can you swap the sensors and see if your readings are consistent?

Does your resin change colors? How do you know when it's exhausted? Usually, the TDS bouncing off of zero is a good clue, so like others say, I'd swap your resin.

Resin can release ions once exhausted, so it's possible that the TDS increases during the resin process. This is used in commercial operations to recycle resin; however, reefers don't use enough resin to make this practical.

I use a two canister resin filter from the filter guys. As soon as the first one exhausts, I swap canisters and refill the first. My TDS has never budged from zero this way.

[sps1-2-b]

I'll swap the sensors after work to see if the readings are consistent. I don't refill the DI resin. I just buy the DI cartridge that Marine Depot sells. All cartridges/filters are 4 mos old including the tfc membrane. The tds meter is calibrated. Thanks for your responses.

[AZDesertRat]

Your water in Anaheim is similar to ours in Phoenix in that a large portion of it comes from the Colorado River, ours via the Central Arizona Project canals your via the Metropolitan Water District of Southern California canal system. Colo River water is very high in TDS and CO2 which are both tough on DI resins and RO membranes.
Your DI cartridge is shot. DI resin begins to release weakly ionized contaminants back into the treated water even before it is exhausted. Some of these include silicates, nitrates and other forms of ammonia and phosphates, all of which are bad for reef systems.
Replace your DI cartridge, I would seriously consider using Spectrapures SilicaBuster DI resin either bulk in a refillable cartridge or in individual cartridges. They custom hand blend it for our water conditions and no other resin wil last as long or work as well.

[sps1-2-b]

Thanks AZDesertRat. I will take your advice and get the Silicabuster DI cartridges.

[sps1-2-b]

Just wanted to give "props" to AZDesertRat. I installed the SilicaBuster and tds is 000 for product water. You're right that the DI cartridge was releasing weakly ionized contaminants back in the water. I even called a retail store and 3 of their techs said that they were dumbfounded on why the tds reading was lower pre DI and higher post DI. They said that's impossible. Well, from experience and AZDesertRat's knowledge it is possible. So stay on top of your DI cartridge bc once its shot your product water is worse than after RO.