I might have one but I'd have to look. I'm probably too far away to help in this emergency but I can suggest some tips for the future. Bulkheads can split when they have been cranked down too tight and/or forced off axis. I've also seen tanks crack when bulkheads are bent off axis by the leverage of a rigid pipe. That's a good reason to use Spa Flex PVC Hose instead of rigid pipe (Schedule 40 PVC pipe is more rigid than Class 200 PVC pipe).
Hopefully there is a powerhead in the tank to keep the water moving while the replacement bulkhead/seal is found.
There are bulkheads that don't tighten with a nut but work awesome. They are called Uniseal. Uniseal is not some crazy new product. It has been used successfully for many years in many applications where a water tight pipe-to-tank or pipe-to-pipe connection is needed. They have an advantage over the common bulkheads because the pipe can wiggle and the seal will not break or leak because they are flexible synthetic rubber.
Here are some links to 1/2" Uniseals.
http://www.usplastic.com/catalog/item.aspx?itemid=89941http://www.bulkreefsupply.com/uniseal-5.htmlThey are less than $2 each. I know, that's such a crazy price that it makes us wonder how it could be any good. All I can say is that Mechanical Engineers developed these things to work for low cost so that companies can make a better profit.
Aloha,
Mark
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