New Pool Owners

We have just installed a new approximately 12,000 gallon salt water pool. We are definitely pool virgins !!!!
We started with a pool company maintaining the pool. We did not feel we were getting what we paid for....
So now we are trying to take over ourselves....started having water tested at a local pool store and have quickly found that we are always needing to buy expensive chemicals to add to our pool on an almost daily basis .......
I have recently found your forum and so glad.......We have bought a OTO kit from walmart and now trying to test and adjust the water based on this testing. But have found that are chlorine is always high so now I find out that we can not judge the ph level with the chlorine being high. We have turned down the salt cell, only thing we know to lower chlorine.
SOOOOO after all that chatter, I would like to know where to start and exactly which test system I should buy so we can maintain our pool to the best of our ability. I clicked on the amazon site and almost bought the TAYLOR TECHNOLOGIES INC K-2006 TEST KIT COMP CHLORINE FAS-DPD, but decided to cancel until I received an educated direction on which way to move forward from now and be sure I get the correct testing kit.

Thank you so much for your help.