Sludge when aerating saltwater

When I make a batch of salt water for a WC, I make 20 gallons of water with my RO/DI, add salt, throw in my heater, and aerate with an air pump for 12-24 hours. I always check my RO/DI water at the start of each batch to make sure I'm still at 0-1 conductivity. I use Reef Crystals as my salt.

Everytime I make a batch, I get a brownish sludge that forms and floats after a few hours of aerating. I just skim it off so it's not a big deal, but I'm curious what it is. Has anyone else using Reef Crystals seen something similar? The only thing I can come up with is microbio coming out of my RO/DI because that wouldn't show up as conductivity or organic impurities in the Reef Crystals.

Thanks for any insight.

 

It's clay. Luckily clay is inert and just settles or is removed via mechanical filtration.

It has nothing to do with Reef Crystals. Almost all salts have some.....some batches just have more. Trust me, we could not afford this hobby if our salts were made with ACS, analytical, or other higher grades of chemicals. The clay is just a byproduct of the mining process.

 

That might be it. It seems to coagulate pretty well, so there's something pulling it together, but that may be some residual settling aids. Regardless, it has driven home to me the importance of aerating my saltwater before dumping it into the DT. ;D

 

Some brands even add a little on purpose as an anti-caking agent.