What doesn't exist for reefing yet but you really, really wish it did?

[Myka]

Originally Posted by ScubaSteve

Because Calk/Alk probes seem to be pretty popular I've been thinking this over quite a bit today. I experimented making some ion-selective solid state probes a few years back that were very cheap to make. I think I can adopt this to work with calcium without too much issue and, if I'm lucky, I might even be able to do the same with all as well.

Alk is the tricky one, but you should know that.

Mindstream claims to have it figured out, but they are lacking funding badly since a serious failure in their Kickstarter program.