I also have an indoor pool and it is used commercially as an aquatic Physical Therapy pool. Checking and maintaining FC and PH is very important to me. I use a 15-gallon liquid chlorine setup by Stenner that pumps a set amount of chlorine into the pool every day. I check FC at least twice a day. If it's low, I turn the pump up and so forth. I think that what you really want to know is whether or not the FC has changed from the last time you checked. I use a Lamotte Color Q and also the Taylor DPD-FAS. They consistently give me different results, but when one goes down, the other one does too, so I make the correction. They are always in the same ballpark. Taylor makes a little gizmo that you put on the bottle of powder and gives you exactly the same amount each time. I use it with a 10 ml sample and it turns pink every time. I agree that if yours doesn't, you have zero FC. If your room has windows, then you have to either add CYA or put a coating on the windows to block out ALL ultraviolet sunlight. If you don't, the Chlorine will dissipate in a matter of hours. My pool room has 3 smallish windows that have the coating so I don't use CYA. I have spent months dealing with pool chemicals but I think that now I have got the routine down. My 10,000-gallon pool "eats" a 15-gallon container of 12.5% CL in 3 months. It costs me $72.00 for a refill. The water temperature is also important. I read that for every 10-degree increase of pool temperature, the FC should be increased by 1 ppm. I keep my FC at 2.5-3 ppm. The temperature is 95 degrees. The nice thing about an indoor pool is that it's not affected by weather, rain, temperature shifts, etc. You can get into a routine. Also, I keep my TA around 75-80. Any higher and you'll be fighting PH. I add about 8 oz. of Muriatic Acid (Baume 22) every Monday. That keeps the PH between 7.4-7.6.
