Hello, I drained 3/4 of my pool, blasted off the scale, and refilled it towards the end of August. Using two softeners, I refilled it mostly with soft water and there's a soft water feed line attached, so this is not the typical Vegas hard water. My CH is typically in the low 240s. I then installed a SWG and finished adding salt by August 28. I test my water either daily or every couple of days, and since things settled down, I have a crystal clear pool and the water feels great -- no itching, burning, or anything. I get consistent readings, but some of them aren't what the Pool Calculator wants me to have and the goals set by the Pool Calculator are just WEIRD. These are today's readings:
FCL: 4.98 (a bit high because of being out of town for a couple of days -- usually around 3.5 or 3.8)
CH: 255 (usually around 240)
CSI: -0.2 (balanced)
Salt: I just entered 3400 ppm into the Pool Calculator because I do not have test results for salt. See below.
Here are the questions/issues:
1) The pool calculator says my ALK should be 60-80. I have never gotten it that low since refilling the pool. On Monday morning before leaving town, I tested the water and got a PH of 7.8 and ALK of 93. I'm almost always at 7.8 no matter how much acid the Pool Calculator tells me to use to get down to 7.5. Okay, so I figured I'm going out of town so here is my chance to get the PH way down and reduce the ALK. I used the calculator to tell me how to get the PH down to 6.9 and it told me to use a bit less than 3 quarts of muriatic acid (29%). Instead I actually used almost a full gallon and as you can see, the PH today (Thursday) is already (back at) 7.6 and the ALK is at 91. Thus I reduced the PH a whopping 0.2 and the reduction in ALK is within the margin of error. Two weeks ago my ALK was actually less than my current reading. It seems obvious that the Pool Calculator doesn't ask me to add enough acid, but I have no idea how much more I should be adding in order to reduce the ALK level.
2) The salt test strips I bought from the pool store tell me that there is only about 1100 ppm of salt in the pool. That is ridiculous -- I added 14 bags to my 19,000 gal pool as the bags recommend and the pool tastes pretty salty. The SWG wants 3400 ppm and is happily generating lots of chlorine at only 60-80% capacity. Do I need to get better results? Salt doesn't seem to change the results much on the Pool Calculator.
3) If I used the goal settings in the Pool Calculator (splitting the differences on the ranges), it says my CSI would be -0.34 with the "potential to become corrosive to plaster." Yet the same Pool Calculator shows that my existing values are "balanced" at -0.26 and I have had frequent results around 0.0 which are also shown as balanced. What gives? Why would the Pool Calculator give me GOALS that would result in plaster corrosion??? And of course if I add even more acid in order to get the PH down, the Pool Calculator is going to have a cow about plaster corrosion. I even tried adding the recommended amount of borate into the Pool Calculator goals to see what would happen, and that makes the "potential to become corrosive" worse yet.
4) Even though the Pool Calculator says my pool is balanced, I am still getting some scaling and calcium spots where the spa spills over into the pool. Thus far we have been able to eliminate it by spraying it with white vinegar, but maybe I should work harder to reach the Pool Calculator goals and risk the plaster corrosion in order to keep the &*%&& scale out? Maybe it makes a difference that my pool is Pebble-Tec instead of plaster???
I don't know what to believe any more. Am I overthinking this? I don't know whether I should trust the Pool Calculator or what.