Hi, I think this is my first time posting here, although I have read a lot of posts over the years. Learned a lot, but still a lot I don't know.
I have a gunite pool (around 16K gallons) that is about two years old now. I do my own testing with one of the Taylor kits and have generally been good about watching the PH and FC levels. A bit spotty on the CYA and TA levels and rarely tested for CH. Well, now my CH has hit 960 and seems like it may still be climbing. I decided to drain some water out and refill to deal with it only to discover I have a calcium buildup ring on the tile all around the pool at the water level. I hadn't noticed it before because we have an automatic water filling device to compensate for water loss so now the water level doesn't really change at all. I am hoping to get ideas about how to best bring down my CH and also remove this buildup.
The current water readings are:
FC=1.2. (I usually shoot for 5-9 using Cal Hypo powder in 24 oz increments depending on how much use the pool got, temp, and if any algae is present. Didn't add Cal Hypo this time because am draining some water .)
PH=7.6. (My water has a naturally high PH - over 8 - and I am constantly battling the rise. I use muriatic acid (31%) in 26 oz amounts to bring it down.)
CYA=around 33. (This used to always be closer to 50 and 60, but has recently come down to the 30-40 range. I did have a period of time very recently where it was actually at 0 and I realized I had forgotten to check on the trichlor tablets I often use in the dispenser. Adding two seems to have solved that problem.)
TA=Around 85. Initially, this was in the 120s or so, but has been falling somewhat steadily over time. I recently got a reading of 40, but that could have been a mistake on my part, I suppose.
CH= 960! This used to be much lower at around the mid to high 300s, but apparently has risen quite a bit over the last two years. Unfortunately, I was not worried about this given the initial readings and never seeing signs of buildup so I hardly ever measured it. It was around 750 a year ago. Too bad I didn't realize that was a problem.
My average pool temps during the day right now are in the high 80s and sometimes low 90s (we have solar heating). After a couple hot days and especially if the kids use the pool a lot, my FC plummets and I have to add a lot of Cal Hypo. Sometimes I am slow to do so and start to see a little algae building up on the pool walls. Scrubbing it and adding the chlorine deals with it easily enough. My water is almost always crystal clear. We also have sheer descents so it can get a lot of aeration.
But, is using Cal Hypo a mistake at this point? Should I be switching to non-chlorine based oxidizer? Also, how much water should I attempt to replace? I am draining it right now via a garden hose and pool pump, but it is pretty slow going and I don't know how to turn off the automatic water filler either. A little concerned about the sun beating down on the gunite if water is drained below tile level (I live in the Sacramento area so temps are in 90s much of the time).
Separately, I have read that if my calcium buildup is the carbonate kind it isn't too hard to remove, but if is the silicate type, it is a real pain. I don't quite know what I have because I tried to test it with muriatic acid to see if it would foam, but while it did foam a tiny bit on the grout, it didn't on the tile. However, that could be due to there not being much actual material buildup on the tile since I can't even feel it with my finger - it's just ugly. Is pumice stone really the only way to try and remove it? Are there some chemicals I should try? Is muriatic acid a good way to do this without damaging the tile? I am attaching a picture of the buildup.
Lots of questions, I know, so I apologize. Thanks, in advance, for any help!
I have a gunite pool (around 16K gallons) that is about two years old now. I do my own testing with one of the Taylor kits and have generally been good about watching the PH and FC levels. A bit spotty on the CYA and TA levels and rarely tested for CH. Well, now my CH has hit 960 and seems like it may still be climbing. I decided to drain some water out and refill to deal with it only to discover I have a calcium buildup ring on the tile all around the pool at the water level. I hadn't noticed it before because we have an automatic water filling device to compensate for water loss so now the water level doesn't really change at all. I am hoping to get ideas about how to best bring down my CH and also remove this buildup.
The current water readings are:
FC=1.2. (I usually shoot for 5-9 using Cal Hypo powder in 24 oz increments depending on how much use the pool got, temp, and if any algae is present. Didn't add Cal Hypo this time because am draining some water .)
PH=7.6. (My water has a naturally high PH - over 8 - and I am constantly battling the rise. I use muriatic acid (31%) in 26 oz amounts to bring it down.)
CYA=around 33. (This used to always be closer to 50 and 60, but has recently come down to the 30-40 range. I did have a period of time very recently where it was actually at 0 and I realized I had forgotten to check on the trichlor tablets I often use in the dispenser. Adding two seems to have solved that problem.)
TA=Around 85. Initially, this was in the 120s or so, but has been falling somewhat steadily over time. I recently got a reading of 40, but that could have been a mistake on my part, I suppose.
CH= 960! This used to be much lower at around the mid to high 300s, but apparently has risen quite a bit over the last two years. Unfortunately, I was not worried about this given the initial readings and never seeing signs of buildup so I hardly ever measured it. It was around 750 a year ago. Too bad I didn't realize that was a problem.
My average pool temps during the day right now are in the high 80s and sometimes low 90s (we have solar heating). After a couple hot days and especially if the kids use the pool a lot, my FC plummets and I have to add a lot of Cal Hypo. Sometimes I am slow to do so and start to see a little algae building up on the pool walls. Scrubbing it and adding the chlorine deals with it easily enough. My water is almost always crystal clear. We also have sheer descents so it can get a lot of aeration.
But, is using Cal Hypo a mistake at this point? Should I be switching to non-chlorine based oxidizer? Also, how much water should I attempt to replace? I am draining it right now via a garden hose and pool pump, but it is pretty slow going and I don't know how to turn off the automatic water filler either. A little concerned about the sun beating down on the gunite if water is drained below tile level (I live in the Sacramento area so temps are in 90s much of the time).
Separately, I have read that if my calcium buildup is the carbonate kind it isn't too hard to remove, but if is the silicate type, it is a real pain. I don't quite know what I have because I tried to test it with muriatic acid to see if it would foam, but while it did foam a tiny bit on the grout, it didn't on the tile. However, that could be due to there not being much actual material buildup on the tile since I can't even feel it with my finger - it's just ugly. Is pumice stone really the only way to try and remove it? Are there some chemicals I should try? Is muriatic acid a good way to do this without damaging the tile? I am attaching a picture of the buildup.
Lots of questions, I know, so I apologize. Thanks, in advance, for any help!
Yes, the cal-hypo is related to your elevated CH level and scale problem along with allowing the pH to rise over 8.0. Those two things alone twill drive up your "CSI" level (see 
