Hi Wayne

I am in the telecom industry and on many occasions seen stainless steel corrode. You cannot for instance use stainless steel bolts on a galvanized sheet. Within months it will corrode away. I agree with Paul that in your case it might not be pure stainless steel

Some interesting facts:

For a wide variety of applications, stainless steel competes with carbon steels supplied with protective coatings, as well as other metals such as aluminum, brass and bronze. The success of stainless steel is based on the fact that it has one unique advantage. The chromium in the stainless steel has a great affinity for oxygen, and will form on the surface of the steel at a molecular level a film of chromium oxide. The film itself is about 130 Angstroms in thickness, one Angstrom being one millionth of one centimeter. This is like a tall building being protected from the rain with a roof the thickness of one sheet of ordinary copy paper.

There are over 150 grades of stainless steel, of which fifteen are most common.

Stainless steels are corrosion RESISTANT, not corrosion proof. Chlorides and fluorides and other substances can, and do, attack stainless steels.

Type 304 stainless steel is corrosion resistant but metals are not corrosion-proof. Type 304 stainless steel contains nickel and chromium and some other elements, but the principal ingredient is still iron, and what you are seeing is probably rust

Thank you marius for that detailed explaination. Lets say that the easy is made of a sub standard stainless steel why is only mine rusting...remember i have already had 2 from the same supplier...thats why the supplier is saying its my water or rather electricity in my water because nobody else is having this problem. For example Bobby on this forum has had his in his pond since October 2007 and has had no problems.

Can I be honest? I am lost and can not give you an answer.
If you look at the pattern of “rust’’ it seems that some other substance was in contact with the drum. Viewing the inside of the drum, it looks like the ring was made from iron and not stainless steel and welded to the drum. I will try my best to get more info about what is going on.
What I do know is that the potassium permanganate can’t attack steel

Hi Marius, the marks on the easy was definatly not caused by something being in contact with the drum. The drum sits in a vortex, so the water is spinning around it the whole time.

You can see it in the thread about my pond setup.
http://koionline.forumotion.com/posts-on-pond-building-f17/pond-progress-wayne-barker-32-000l-cape-town-t289.htm

Found the following bits and pieces for you. It does not give a clear indication of the problem since I am sure your water will be of good quality, but worth reading:

Chloride content of the water is the most important factor causing corrosion in stainless steel. Low pH will have an effect as well

MICRO ORGANISMS.

If the protective oxide layer is removed from stainless steel because of rubbing or damage, the "bugs" can penetrate through the damaged area and attack the carbon in the metal. Once in, the attack can continue on in a manner similar to that which happens when rust starts to spread under the paint on an automobile.

PITTING (need to read the web links below to fully understand )

This is an accelerated form of chemical attack in which the rate of corrosion is greater in some areas than others. It occurs when the corrosive environment penetrates the passivated film in only a few areas as opposed to the overall surface. As stated earlier, halogens will penetrate passivated stainless steel. Referring to the galvanic chart you'll note that passivated 316 stainless steel is located nine lines from the bottom and active 316 stainless steel is located thirteen lines from the top. Pit type corrosion is therefore simple galvanic corrosion, occuring as the small active area is being attacked by the large passivated area. This difference in relative areas accelerates the corrosion, causing the pits to penetrate deeper. The electrolyte fills the pits and prevents the oxygen from passivating the active metal so the problem gets even worse. This type of corrosion is often called "Concentrated cell corrosion".

http://www.gilsan.co.kr/eng/stainless/stainless4.htm

http://www.mcnallyinstitute.com/04-html/4-1.html

http://www.weldreality.com/stainlesswelddata.htm

http://www.recreonics.com/fyi/stainless_steel_maintenance.htm

http://www.healthywater.com.au/water_facts/waterfacts02.cfm?cat=commercial

Now im lost, this is so compicated....i feel like a noob.

Whats the solution for pitting? What must i do to prevent it?

These sites will explain the process of pitting (Concentrated cell corrosion)

NASA might not know much about ponds but I am sure they had a few metal related problems on the space crafts, lol.

http://corrosion.ksc.nasa.gov/conccor.htm

http://www.tpub.com/content/UFGScriteria/UFC3-570-06/UFC3-570-060020.htm

http://www.corrosionist.com/Corrosion_Type_Concentration_Cell_Corrosion.htm

http://corrosion-doctors.org/Principles/Cell.htm

Article on how to correct the corrosion:

http://www.gordonengland.co.uk/corrosion.htm

I think the ‘electricity in the water’ the guy referred to was more a matter of two or more areas of the same metal surface in contact with different concentrations of liquid that are causing an electrical potential between the large area of the cathode (passive film) and the small area of the anode (active metal). Rapid pitting of the active metal will result.
It is like sticking an electrode into a lemon and you get a small voltage or battery.

The question still remains what in your pond is causing this reaction since you are the only one having this problem. Hopefully someone can come up with an answer for you

Regards
Marius

Hi All, i think i have found something.

I tested my pond water today and found 0.2 ACV in my pond water but its only in my filters....my pond itself does not register at all. I am not sure how or why and so im checking my earth lines. I have a earthleackage of 0.6 from my house. With all the power off i still get a earth leakage of 0.1?...

The pictures below shows my municipal DB Box. If i look at the wire setup it looks wrong to me but i am no electrician. There seems to be a loop of some sort between the neutral and the earth wires. There are 2 incoming earth wires, a green and yellow and plain copper wire.

Are there anyone with a bit more knowledge than me in this subject?





The sticker mentions that the box is earthed on neutral. I have spoken to several people so far and no one has ever heard about doing it that way but non of them are electricians either so i guess it does not count either.

Since the neutral point of an electrical supply system is often connected to earth ground, ground and neutral are closely related. Under certain conditions, a conductor used to connect to a system neutral is also used for grounding (earthing) of equipment and structures. Current carried on a grounding conductor can result in objectionable or dangerous voltages appearing on equipment enclosures, so the installation of grounding conductors and neutral conductors is carefully defined in electrical regulations. Where a neutral conductor is used also to connect equipment enclosures to earth, care must be taken that the neutral conductor never rises to a high voltage with respect to local ground

Voltages created in grounding (earthing) conductors by currents flowing in the supply utility neutral conductors can be troublesome. For example, special measures may be required in barns used for milking dairy cattle. Very small differential voltages, not usually perceptible to humans, may cause low milk yield, or even mastitis (inflammation of the udder). So-called "tingle voltage filters" may be required in the electrical distribution system for a milking parlour.

Connecting the neutral to the equipment case provides some protection against faults/shorts, but may produce a dangerous voltage on the case if the neutral connection is broken.

Combined neutral and ground conductors are commonly used in electricity supply companies' wiring and occasionally for fixed wiring in buildings and for some specialist applications where there is little choice like railways and trams. Since normal circuit currents in the neutral conductor can lead to objectionable or dangerous differences between local earth potential and the neutral and to protect against neutral breakages, special precautions such as frequent rodding down to earth, use of cables where the combined neutral and earth completely surrounds the phase conductor(s), and thicker than normal equipotential bonding must be considered to ensure the system is safe
Where a ground connection has a significant resistance, the approximation of zero potential is no longer valid. Stray voltages or earth potential rise effects will occur, which may create noise in signals or if large enough will produce an electric shock hazard.

Stray voltage occurs when electricity “leaks” from the black wire directly to the red or ground wires before passing through the device to be powered. These leaks produce only small amounts of electricity

I think you have a bad contact somewhere. This can cause a voltage difference even within the same wire. To many joining points on the same wire can cause loop currents.

Best way to explain this is when you use thin wires to ‘jump start’ another car. You struggle to get the other car going and you ask yourself: ‘‘what is wrong, I have connected the flat battery to a good battery but still no luck’’
Well, do yourself a favor next time this happens. Measure the voltage on the good battery and then on bad battery while you turn the key. You might find let say 13.6V on good battery but only 9.5V on the bad side. This missing 4 volts is a result of a voltage drop within the wire itself due to resistance.

Just for a matter of interest. When you did your measurements, did to stick the one probe of the multi meter to the earth wire on the motor and the other end to the easy drum inside the filter??

Ok, found something else. the 0.2 ACV in my vortex filter seems to be coming from my speck porpoise 0.45kw pump that is sucking from the vortex which contains the eazy filter.. If switch it off the 2V disapear the same if i close the ball valve on it. I have 2 pumps and only the one seems to "leak" electricity as i also configured the other one to suck from the vortex and then there is no electricity in the water. So it seems to be a faulty pump.

Check the wiring inside. Electronics might seem interesting but not easy to understand. Take a two way radio and place a flouresant lamp next to it. (Without wires connected) Start talking on the radio and the lamp will glow (but not enough energy to keep your pumps going when ESKOM fails). You can take the same meter that you used to test he pond and stick the 2 probes in the air next to your TV ( Not plasma) and you will be surprised about the magnetical energy you pick up ( Eskom still sucks since it won't power the pump)
On a more serious point, check your wiring and connections. 200 milli volts might not be much but since you have a problem with the easy, it will be good to get feedback from you. You never know, someone else might have a similar problem in the future

I removed the 0.45 pump on sunday and borrowed another one from my dealer while mine is in for a repair/service.

Then i noticed that i still had a 0.1 ACV in my pond!

It turned out that my terminals of my one 33w UV light was slightly wet and this was causing it. I did not pic it up as i was switching the UV lights on and off at the same time as the faulty pump. Im now wondering if the pump was faulty....hmm well tolate now its already at speck. I think the O-ring on the UV was leaking slightly but not so much that i would notice. I hanged the termnals out to dry and the problem has disappeared since then.

So at the momment my pond is perfect.

Thanks for feedback Wayne. I am sure this can happen to anyone and a small problem can cause big trouble. In my old pond I had an open neutral wire going to a small pump. Had a big shock when I wanted to clean the pump. Had no earth leakage on pump.