Update to Tin in RO Wiping Out Tank


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Hudson Yards
Background - A Tank Wipeout
In June I moved to an apartment in a brand new building. It took me about a month to get the proper adapters to hook up my 6 stage RO/DI unit to my kitchen faucet. During that time I was using seawater in a box (Nature's Ocean Nutri-SeaWater) to fill the tank and do water changes, and everything was fine for that month.

When I finally got the proper adapters for my RO/DI, I replaced the sediment and carbon media (the DI resin was relatively new and still properly colored), slipped in a new RO membrane and made my own RO/DI water for the first time in the new apartment, and mixed up some saltwater. From there things went downhill really fast.

Within 24 hours the stony corals (SPS and LPS) had lost color and died, and all the soft corals completely closed. All the tank's water parameters were within normal limits. Still, thinking something went wrong with the water change I did another to try and rectify it and remove all the pollution caused by the coral die-off. "The solution to pollution is dilution," right?

During the next 24 hours every living thing in the tank except one fish, one cleaner shrimp and the zoanthids I could pull out of the tank died. When I say every living thing, I'm not kidding. All amphipods, copepods, aiptasia anemones, mysis shrimp and bristle worms were wiped out.

The Hunt for a Cause
Everything still alive lived in buckets of Nature's Ocean Nutri-SeaWater for the next 4 weeks while I tried to figure out what went wrong. I sent a sample of my RO/DI water to Triton Labs for testing and waited.

During that time a heater in one of the buckets malfunctioned and killed the cleaner shrimp. The water got so warm it felt like bath water and the only remaining fish (an Aiptasia Eating Filefish) barely survived.

A week later I got the results back from Triton which showed levels of tin in the RO/DI filtered water were through the roof at 53 ppm. I did not test the pre-filtered tap water since all I really needed to know was if there was something wrong with my RO/DI water, and there was.

The Search for a Solution
I searched extensively for info on how to deal with this from others reefers who'd had the same problem. As it turns out, nobody did. All accounts of tin in reef tanks were caused by equipment corrosion and easily remedied with water changes once the offending piece of equipment was found. Those aquarists who tried additives on the market designed to remove heavy metals like lead, copper and iron met with mixed results. I had to figure out how to remove the tin from the RO/DI water before it ever made it into the tank.

A Potential Solution
After a couple weeks of discussions with the staff at Triton, PolyFilter and BRS I think I've got a way to get the tin out of my RO/DI water.

I had been using one canister of DI resin (mixed bed cation/anion resin) in my RO/DI. That may have worked for the water at my old apartment, but wasn't enough to remove the excessive positively charged tin ions in my new water source.

What I need to do is expand my RO/DI so it has 3 resin canisters; the first with cation resin, the second with anion resin and the third with a mixed bed resin. The first will remove any positively charged ions like tin and lead. The second will remove negatively charged ions like phosphate, chlorine etc.. The third will catch any stragglers that may make it through the first 2 DI stages.

I have to wait for payday on Friday before I can order the new RO/DI addons and then have Triton again test the water coming out of it. I'll post another update when I have those results.
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