Hello: I live in SW Michigan and have a rectangular, gunite pool. It is 36' x 18' and holds approximately 30,000 gallons. I have lived here and wrestled with this pool for 8 years. This year has been a real head-scratcher for me, but I guess I've just always had good luck. I believe I have mustard algae that keeps coming back within a week or so of eradication (or so I thought). I have been using AquaCheck 6 panel strips, but I am going to order a Taylor test kit via the links provided here. My CYA is low (0 or below) and PH high (8.4 range). TH, TC, FC all appear to be good. TA had been a bit high. I added 2 gallons of HCL last week and it helped. PH appears to be between 7.2 and 7.8, but CYA is still low (somewhere between 0 and 30, but closer to 0). TA came down closer to 180. I am vacuuming all visible algae to waste right now (pool level coming back up now) and will brush walls. I picked-up another 2 gallons of HCL and 10 gallons of liquid chlorine. I have more reading to do on your site, so not quite sure how many gallons of Chlorine I'll dump in. I'll add 1 gal of HCL and wait to test, but I'm guessing I'll end up adding both gals. It appears that my chlorine isn't working effectively with my CYA so low. Sorry for this yawn-inducing post, but... this is why I have joined. It didn't take me long to realize the moderators here know what they're doing. I appreciate reading and learning from all the experienced pool lovers here.