Well, good news...
I unloaded everything on the kitchen table and found the dual in-line TDS meter inside of a package. Man, it's much smaller than I imagined, but that's no big deal. The thing that I am frustrated with is the length of the electrical cables that comes with it. Anyways, at least it had pretty good directions that came with it. I'm satisfied.
I installed all of my filters... man, I got some filters. lol. 9 stages of filtration - it ought to do what I want it to do now. No more mistakes and creeping TDS. I'm also going to buy a sensor that I can program to tell me when the filters need to be changed and I can program it for different things. I can't risk problems coming from not having clean top off water.
I also discovered a possibility of something that might have crashed the last several tanks that I have owned. I was using a black silicone sealant to do a lot of the silicone work that I needed done... Nothing to unordinary about that... but what it was was GE Silicone II, which has a mold and mildew inhibitor in it - chemicals which kill bacteria and all kinds of stuff - and it was leaching into my tanks because I was using it for various projects. Well, through research and asking some questions, I found out that there are two different kinds of silicone. One is an adhesive and one is a sealant. Adhesives are much stronger and are used to build aquariums... So, I'm buying an adhesive black silicone to build the bean animal overflow.
I am still unsure what the potential dimensions should be on the drain box,.. but I will figure it out.