Good pool chemistry should include a good water testing kit and the proper levels of:
1. pool chlorine
2. combined chlorine (chloramines)
4. total alkalinity (TA)
5. calcium hardness
6. cyanuric acid (CYA)
Swimming pool chlorine is the sanitizer of the pool and should be kept between 1.5-3.5ppm. Your pH should be between 7.6-7.8, not 7.2. You will use too much pool acid to keep it at that level. Total pool alkalinity (TA) is between 80-100, calcium hardness between 150-250, and cyanuric acid between 20-40ppm.
The maximum you should allow for TDS is 1,500ppm. There is really nothing that can be done to lower your TDS short of draining some or all of the pool water and starting over again. The best thing is to take your water into your local pool store for a proper TDS test.
There are basically two types of water testing kits:
1. Dropper Water Testing Kit
2. Test Strips
CYA is a stabilizer for your chlorine and is used for only outdoor swimming pools. A good water testing kit will have a CYA reading. Careful reading should be taken for CYA as sudden drops or increases will cause your chlorine to lose its effectiveness.
The first is a dropper kit that should include readings for chlorine, combined chlorine, (chloramines) pH, alkalinity, and hardness. The most widely used type of dropper test kit is called the FAS-DPD K-2006 Taylor Reagent. These pool water test kits commonly use a type of "test tube" and eye dropper application.
Adding the Reagents to the water produces a change in the test water color. Then this color change is compared with the accompanying chart. Some kits may have you "count" the drops and do a little math to get the correct reading. The two main kinds of dropper systems are called DPD and OTO pool water testing kits.
DPD, or N,N Diethyl-1,4 Phenylenediamine Sulfate, measures the free chlorine as well as pH, combined chlorine, hardness, cyanuric acid, and alkalinity. It's also called the "pink test system" due to the chlorine will, at first, become pink in color. You need to keep your DPD pool water testing kit fresh and away from direct light as this may skew your readings. The best for your money is the FAS-DPD K-2006 Reagent Test Kit.
DPD is a little more time consuming and complex due to the proper "swirling" technique, but when properly done you'll find this system of tests is the most accurate.
OTO, or OrthoTOlidene is the other brand of dropper pool water test kit. This pool water testing kit can test for all readings, but usually test for chlorine and pH, and is often called the Duo Test Kit. If you're going for a less expensive brand then this would be the pool water testing kit for you. Designed for a pool or spa with a smaller bather load and for the do-it-your-selfer, it's a complete system in a convenient package for great swimming pool care.
The 2nd type of test kit is called Test Strips. These strips allow you to simply dip the strip into the pool water then compare the various squares on the strip to the corresponding chart. The strips should include the levels of chlorine, pH, alkalinity, and hardness.
These strips are fast and easy and eliminate the need for taking samples and counting drops. The basic 3 and 4 square strips can measure chlorine (sanitizer) pH, alkalinity, and hardness all at the same time. You can get these swimming pool chemistry readings within a matter seconds. Remember to follow the instructions carefully and don't take any shortcuts while testing your chemicals.
Use your best judgment and get the best water testing kit for your situation. Some people like the DPD or OTO water testing kit. Some like the Test Strips. The main issue is to test your water on a regular basis, no less than once per week, maybe even twice, to get the best pool water that you deserve.