Stainless Steel Safety

[SteveP]

I have a couple of items I want to use in my reef system (a float valve and a Danner Supreme Mag Drive pump) that have stainless steel fasteners.

Now, I have heard both that you NEVER put steel, stainless or otherwise, in salt water, and also, that stainless in the tank is harmless/no big deal.

Any ideas/experiences out there?

Thanks -

 

[dnjan]

Type 316 stainless is OK. Corrosion is very slow. Type 304 (and others) are much cheaper, Perfectly fine for freshwater, but will corrode in saltwater.

Unfortunately, it is hard to tell the difference until they corrode.

 

[Scooterman]

True, True!

 

[Krish]

Well, the specs on the supreme mag drive pumps state that they are for fresh and saltwater applications. The only problem you may have is if your mag drive is one of the "pondmaster series" of pumps (the ones with, I think, the 18ft power cord). They are not recommended for saltwater use. Hope that helps.

 

[snobanker]

304 is still slightly magnetic, and 314 is not....I think

...wait, let me say that a magnet sticks to 304 and not to 314......SS isn't "magnetic" the way I made it sound above

 

[SteveP]

Thanks to all for the input, much appreciated -
Steve

 

[dnjan]

304 is still slightly magnetic, and 314 is not....I think

...wait, let me say that a magnet sticks to 304 and not to 314......SS isn't "magnetic" the way I made it sound above

You will have a very difficult time getting a magnet to stick to 304 stainless, since it is austenitic (as is 316), and therefore non-magnetic. The 400-series stainless steels (typically used for better chef's knives, etc.) are generally magnetic, but not the 300-series.

Most important - don't use a magnet to test whether a stainless steel is OK to use in saltwater. You won't be able to tell 304 and 316 apart with a magnet.

 

[snobanker]

My bad Don...I believe you are correct....when I was a city traffic engineer in my previous life BC (before cop ) we used to use a magnet to make sure the contractors we hired to build traffic signals were using the spec'd SS hardware.....They would try to use the wrong grade of SS because of the cost differences..... I was just mentioning it as kind of trivia thing...not as a way to test for "reef safe" SS

 

[dnjan]

304 bolts would probably be fine for traffic signals. They were probably trying to sneak in cheap, plated steel. 316 is often describes as "marine grade". For example, when you look for hose clamps, most are stainless. But the expensive, marine-grade ones are the ones made with type 316 (and they are the ones that are significantly more expensive).

I have used marine-grade hose clamps for connecting flex tubing to a return pump in the sump with no problems for years. However, the time I tried to use a non-marine-grade hose clamp where a flex tube connected to a return fitting just above the tank (in the hood, below the lights), salt creep forced me to replace that hose clamp with a marine-grade one in less than a year.