Rust in sps plug
 

I have been having some issue with STN on some of my SPS. Today I notice rust mark on the bottom of a plug (2") that a coral was mounted on. The coral was bought in April. I started to have issue with STN in June. I was wondering if this could be the cause of the STN ? Thanks, Mark

Id like to follow... No STN here but I have noticed the rust on the bottom of a couple of plugs...

Same here. A little rust on the plug and I have recently had some STN in my tank.

This is a 2" plug with 2 1/4" lines of rust.

I know of one store that was using an aragonite plug from one of the e-bay sellers that had the same problem. They switched to the ceramic plugs and the problem went away. I see a lot more stores using these over the concrete based plugs.
[url]http://www.thefilterguys.biz/frag_supplies.htm[/url]

If something is cheaper it isn't always better. You just never know what is mixed in with the concrete that is used to make the plugs. I know of guys that have been using the ceramic ones for years with no issues.

Rust on several aquaculture plugs here, no problems with STN. According to RHF, iron isn't really very soluble in saltwater. It rusts, but it doesn't just outright dissolve. With a large tank volume, I don't think this would be detrimental.

dont corals grow in rusty, sunken ships?

yes but the ocean is huge.

The plug is out and I will see if the STN stops.