Mark, I can answer your question a couple of different ways.
1st, I just like to have something on-hand in case of emergency trouble-shooting. I've read some posts on this forum that some LFSs have prices cheaper than online. Just wondering which ones. I'm not really looking to spend $100+ on a monitor or controller.
2nd, I need a pH test kit for my jellyfish tank which is very different from a reef. I'm sure it's similar to a fish-only tank but I don't know how things change with no corals in a tank.
3rd, I just upgraded to a new tank (Mike's 50g cube) and I don't know yet what my dosing schedule should be. I'd like to make sure my pH doesn't swing too much by manually dosing. Perhaps I'm just being overly cautious. It would be great if someone would lend me their pH monitor until i get my dosing schedule figured out but i don't know how much of an inconvenience it is to ask.