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Originally Posted by baddiesel1  Just a footnote to add with valuable information: The director of Husbandry at the North Carolina Aquarium, in Emerald Isle returned my call regarding my issues with the through hull fitting (ie bulkhead fitting for land-lovers). Here's his answers:
1. First and foremost, bronze has copper alloy in it (copper & tin). So, it cannot be used.
2. Second, my brass hose bib has copper in it (copper & zinc). So, it cannot be used.
3. I was told the safest sealant to use, is 100% silicone. Like the kind you would use for an aquarium.  Guess you can tell I'm a newbie. I'll remove the media from my bio-filter tank. Catch the 3 fish and place them in it. Shut down the pump, drain the 300 gallon horse trough. Thoroughly dry it, and install a nylon or plastic bulk head/through-hull fitting (after coating the flanges and threads with silicone) and tightened it. Then, using a hair dryer on low heat, I'll speed up the curing process of the silicone. Re-fill with water and check for leaks. Hope I can accomplish all this before my 3 fish get stressed from being couped up in the 100 gal tank. At any rate, copper is a BIG NO-NO!!!  |
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I didn't think about the bronze
Here's some interesting reading from Jim North (the moderator here) on copper and Zinc :
http://home.comcast.net/~jnorth71/koi/ Go Down the page to the "Copper and Zinc Kills" link
But don't get to worked up over what you can and can't use.
Use a plastic thru-hull "Marelon" (Spelling?????)
Being your around boats, don't use Silicone. Silicone won't last. I've been preaching Marine sealants on the Koi Forums for years, many, many people use them now, and nobody has ever had a problem that I've heard of. Most "professional" pond builders use urathane sealants in one form or another. A lot of people like the "PL" brand polyurathane sealants available at Lowes, or Depot. They work, but I don't care for them much. They don't have the adhesive qualities that marine sealants do.
Just my 2 cents.............
Here's a bit I wrote on sealants quite a while ago. Most sounds like what I already typed here
One should not use silicone anywhere near a pond. The "aquarium" silicone is formulated for aquariums. Standard silicones available from Lowes or Depot contain talc which absorbs water, which intern makes the sealant brittle, and loses it's bond over time. If you notice in your shower if you have ever used clear silicone, after a few years it starts turning yellow? It still mantains somewhat of a seal, but not that great.
Polyurathane "Marine/Boating" sealants are the best. They are designed for use in sealing underwater protrusions on the bottoms of boats. They stick very well to most things, other than "oily" plastics like rubbermaid stock tanks or the blue 55gal drums. They will seal but if the tank is moved or the plumbing hit they can loose their seal. I hate silicones only because in the many years I have worked on boats once someone applies silicone, it's a pain to have to try to clean the surface from all the silicone residues to get the proper sealant to stick. They can create hell, giving one the false sense that "I used a sealant on everything, but I have leaks?".
Marine polyurathanes are as much of a adhesive as they are a sealant. Some can create bonds that are almost impossible to break. 3M 5200 (available in white at Depot) is one that can create bonds that are virtually impossible to break, the substrate will fail before the sealant. Sikaflex 291 is a good all around sealant, as well as 3M 4200. 3M 4200 dries very fast and usually one can add water within a hour of appling the sealant.
Many people like the PL brand of Polyurathane sealants that Lowes and Depot carries, but I don't care for them. They are far better than silicone, but lack the adhesive qualities I like. Plus is says right on the side "not for use underwater". The PL brand is around $5 a tube for the 10oz caulking gun size, whereas the "Marine/Boating" sealants are in the area of $15-$23 a 10oz tube.
There is another sealant that can be applied underwater, I use it from time to time, and I am the only person I know of on the west coast that will go onto a 60ft yacht by myself and drill a 2" hole in the bottom of the boat while the boat is in the water and install a water pick-up fitting/thru-hull or a depth finder transducer, all the while only my hands get wet. The fitting has to go in from the water side and get a nut tightened up on it from the inside.
I have actually had boat owners leave once they saw the 2" hole shooting up a 3' tall water geiser into their bilge. I have done this at least 100 times and never had one leak, I have been doing them for around 15yrs, and to this day, none of them that I have known of have had to be taken apart and re-sealed. I won't post what kind of sealant it is only because I don't think it's fish safe. It contains sulfides, but what I am getting at is there's far better products other than silicone. Silicone is good for sealing glass and that's about it. The only time I use it is when I need a clear sealant, and that's only when I am working on homes. On boats there is almost never a need for clear.
All marine sealants will continue to cure underwater, as long as they are firm to the touch they are dry enough for water. Most will say "Moisture Cure", that doesn't mean that spraying them with water will speed the drying time. Got in a arguement with a fellow a year or so ago on KP on that subject. The only sealant that will cure faster with water is the one I described in the post above.
02-14-2008
West Marine was good until they went "public", now I am just a number.............. 
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