ebay has one that is aroound 10$ (I dont trust it)
but there is also one around 20$ thats made for pools, to test ph and chlorine
I figure the second one could be really useful during water changes to make sure no chlorine and that I have the right ph because I use IAL
I dont think I can link ebay on here but I can copy paste the description for more infor if needed
its called "Home Swimming Pool Water pH / CL2 Tester"
you think its worth it?