calcium hardness decreasing

[TrevNJPool]

Just a question for my understanding. My CH has been decreasing since my first test results in early July. My original tests were 150. I added some to bring it up to closer to 200. It remained there for a few days then started decreasing. It is now down to 100. What causes the decrease? I know it doesnt really matter because i have a vinyle liner but would still like to keep it around 200. My newest test reults are:
FC 10
PH 7.1ish
CC 0
CH 100
TA 90
CYA 35

I havent added anything except for Borax for ph, bleach, cal-hypo

 

[RobbieH]

Would have to be a leak, or from you doing some major backflushing.

 

[chiefwej]

I wish my CH would go down on its own.

 

[TrevNJPool]

I have had to blow water out 2 times for a lot of rain and add some due to evaporation but no huge amounts of water. I thought that was one of those things that stayed in the water

 

[jblizzle]

The CH does stay in the water. The only way it is lowered is if you are replacing the pool water with water that has a lower CH (like rain). I think the CH can also go down if you are getting a LOT of calcium scaling, usually from having high CH and pH, not likely the issue here.

 

[SunnyOptimism]

Your FC is quite high for your current CYA level and your pH is a bit in the low side. Do you normally keep your pH and FC at those levels??


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[easttn]

What kind of test kit are you using?
Exactly what kind of Calcium product are you using?

 

[TrevNJPool]

The FC is drifting down at the present moment due to slamming because i found some algae when i returned home from vacation. I usually keep FC at around 7ppm. Since my FC was high i didnt bother raising the PH yet. Plan on doing that 2mrow once i can check the PH again

Using the TF100. Dont know what the CH product is. Put 25lbs in sometime in july. I keep records of my test results an noticed it was drifting down.

 

[Patrick_B]

The product isn't the problem. You are simply lowering it by adding fill water with less CH. I wouldn't worry much with your type of pool.