Stainless steel in a reef tank?
 

Should I be concerned about using stainless steel needle valves in a reef application?

Concern for your animals? No, you won't have a problem even with a little corrosion.

Long term reliability? Well that depends a little bit on what type of stainless steel and the design of the needle valve. You will likely get some pitting in crevices. I'm not sure how much it will matter to valve reliability as it really depends on the valve.

I would not worry about using the valves.

It would be better not to.

Would brass be a better choice? I'm looking for something better than the cheap plastic ones that come with some calcium reactors.

no, brass is not a better choice. Stainless is probably your best alternative to plastic.

Copper is a primary alloying element in brass. Corrosion will release Cu ions into the water. While the ammount may be small, Copper and invertabrates dont mix so I would avoid brass.

FYI, I have had some very nice plastic needle valves on reactors. The SMC needle valves from US plastics have worked very well.

I'd personally avoid both of them. Though stainless is mostly iron ,some of it contains nickel and trace amounts of other harmful metals. Brass is worse. Miniscule amounts of free copper will destroy invertebrates.

Titanium is the only metal I would trust

I see a lot of hear-say on the boards regarding concerns about stainless. While these concerns are well intentioned, they are generally not grounded in fact or experience.

yes, stainless contains nickel and chromium, but in a typical use you will not get a significant amount of either into you water column. most of the stainless used in things intended for water or food service will be passive (think inert) in a typical reeftank environment. there are exceptions, notably in crevices where the stainless is in intimate contact with something else like a bushing. In these crevices, you will get a some mild pitting. This typically does not impact the function of the stainless unless this crevice is supposed to form a water tight seal.

I am of couse being very general as there are many many steels that we refer to as stainless. These generalizations will hold true for typical equipment.

I'll close by pointing out that many aquarium pumps use metal shafts. With a few exceptions (bubble king) these shafts are stainless steel. stainless works very well in these applications and causes no harm to the tank.

There are types of stainless steel that are rated for saltwater, and they probably would be fine. Most types of stainless steel are not, and could be an issue. Brass would be very toxic. Titanium is fine in saltwater, but I've never heard of a needle valve made from titanium.

Most stainless intended for water or food service is type 316. As I mentioned above, this will perform reasonably well in most reef applications. Some common alloys like 302 or 304 may perform poorly. You don't commonly find these alloys in high quality components.

Very well said rishma. You sound like you've been around metal in a manufacturing means a good while.

SS comes in several grades. Some is saltwater resistant enough to last many years, some are not.

I use a needle valve on my calcium reactor but it is for the regulation of CO2 and never comes into contact with water. Since the tank valve, regulator body, and pipe is brass I just continued the the original brass needlevalve but I do have stainless solenoids.

The output of the reactor is low pH and high Ca+ so I like on/off barbed drip irrigation valves to close the system for maintence and a "needle pinch valve" or "tube pinch valve" to meter flow. The next option for me would be a peristaltic pump to control the flow through the reactor.

Unfortunately, the toxicity levels for metals can be very low, in the ppb range for zinc and copper, so without any way of quantifying "reasonably well", I would be careful about using such types of metal in a reef tank.

bertoni - I think you misread or misunderstood my post. Copper and Zinc are the primary alloying elements of brass. You and I agree that brass should not be used in a reef because it is toxic.

My comment about reasonable performance was related to type 316 stainless steel, a commonly used stainless in applications such as powerhead impeller shafts. This alloy will pose no threat to reef animals and will perform well in most reef applications as I described in prevous posts. The reason I say it will perform "reasonably well" in a reef is because the component my experience some superficial pitting at crevice locations. This type of corrosion is not normally a performance issue, but I did not want to imply that 316 is a perfect choice for saltwater. If the user wants an alloy that is completely passive in the reef, they will need titanium or another much more costly alloy.

To summarize for future readers:
Do not use Brass in a reef, it contains copper and zinc and may be toxic to your animals.

Type 316 stainless steel is commonly used in equipment intended for water services. It is also used for powerhead impeller shafts. It is safe to use in a reef and will not harm your animals. Some components may experience mild pitting over time but this will not typically cause an issue with performance.

Titantium is an excellent choice for saltwater and should be impervious to corrosion in a reef aquarium (in any applciation I can think of)


cheers

I was worried more about possible interpretations of your post rather than the contents itself. :) It seemed a bit ambiguous about what might be recommended choices.