Just wanted to post a quick update that I am trying out the larger tip size (7/16" - Medium Kit) on these water bottles. Since Lixit sells replacement parts, I ordered just the stopper with the tube for a much lower price from a seller on eBay (it is also available from Windy City Parrot, a local bird supply store, but is currently out of stock, and I found it at a few other small private online shops, but was unfamiliar with them, so I went the eBay route this time).
5/16" is supposed to be the appropriate size for rats and I have seen chinchilla sites selling that size for chinchillas, so it should work fine. However, it just seems like my rats have to work so hard to get enough water out, that I want to give the larger tube size a try. I also saw Jo try to bite the bottle tip, so I think she was getting frustrated by the slowness of it.
In the mean time, I have put back one of their Super Pet bottles because I think it is easier for them to drink from it. Or maybe I am just paranoid. We will see how well the larger tube works.
UPDATE: I did a little more research on tube size. Unfortunately, information is limited. I measured the Super Pet bottle tube and it seems to be 3/8", which unfortunately is right in between the 5/16" and 7/16" Lixit tubes. Will the 5/16" be too small and the 7/16" too big? Everything on the Internet that I could find seems to suggest the 5/16" is the recommended size for rats. However, my rats seem to want a larger tube.
I finally found this article on the Rat Whisperer blog: The BEST Water Bottle for Rats. That article reviews the more expensive Lixit Bird Water Bottles. She is using the 7/16" tube successfully with her rats, even though she says that Lixit recommends the 5/16" for rats. So, I am keeping my fingers crossed that this tube will work better for my rats. I really like this water system, so it would be a shame if the tube size got in the way.
UPDATE 2/27/14: The 7/16" tubes work great for our rats and we recommend the 7/16" (Medium) Kit for use with rats.
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Installation Instructions for the Lixit Glass Bottle Recycle Kit
Lixit Glass Bottle Recycle Kit - 7/16" Tube Size (Medium)
A DIY Mount for the Lixit Recycled Water Bottle Kit