zinc versus aluminum anodes-gctid382008

[Guest]

When to use zinc and when to use aluminum anodes?? Do they do the same thing in the same conditions ???? I boat in fresh water.

Thanks Dan

[Guest]

Zinc for salt use

Aluminum for brackish water

Magnesium for fresh water

[Guest]

finalfling wrote:
When to use zinc and when to use aluminum anodes?? Do they do the same thing in the same conditions ???? I boat in fresh water.

Thanks Dan

With fresh water you want magnesium anodes. Salt water=zinc.

[Guest]

Why??? I'm sure it has something to do with the salinity/Ph. B

[Guest]

Wish I had seen this before I JUST ordered a replacement zinc anode for my Capri, and I do boat in fresh water.

Anyone have a magnesium one I could trade?

[Guest]

If your boat has the Mercathode system on it, you will want to run aluminum anodes. I believe Mercruiser came out with a service bulletin about this due to corrosion issues with outdrives.

[Guest]

I boat in fresh water and use aluminum. Here's why... Although the California Delta (where I boat) is not considered salt or brackish, there is a lot of agricultural runoff, which makes the TDS (total dissolved solids) level of the water rather high. Hence, the water is as conductive as brackish water. Conductivity varies with the amount of rainfall, but it is too conductive for magnesium to be useful. Magnesium wears away in 2-3 months, whereas aluminum lasts about 9 months. I generally replace the anodes in April and October.

Check to see how conductive your water is. Even though it may be considered "fresh" water, it can have sediment in it that would render it too conductive for magnesium.