7 month old replaster

[fgonz]

Okay, so after 7 months of replastering pool with dark gray color quartz and using BBB method religiously, i am starting to see whitish marks at bottom of pool. My CSI has always been maintained around -0.3 to -0.1.

My water balance has been steady and averaging the following during the first 7 months:

FC=4.0
PH= 7.5
TA=60 - 80
CYA=60
CH=300-400

My current readings are as follows:

FC=3.0
PH=7.4
TA=60
CYA=40
CH=500

Could the white marks be calcium scaling? My CSI average does not indicate that scaling would develop.

Would CH at 500 cause scaling?
Should i drain water?

Is there any other way of removing calcium scaling without draining pool?

 

[pwrstrk]

Usually you get scaling when your PH is too high. Your PH looks fine. Your CH is a tad high, but with keeping PH in check that should prevent scaling I would think. Not sure what the white spots could be. Could you post a picture of them ? There is an article in pool school on calcium scaling.
On another note your FC is at the min for your CYA level. Your target should be 7 and never below 3. When your CYA level was 60 your target FC should be 9 and never below 5. Just a heads up. ?

 

[eqbob]

Is it possible that you have some micro fractures in the plaster? Water seeping in behind them and 'eating' the readily available calcium on the underside could produce some white streaks like that. That happened in mine, although the the paster was 2 years old, not 7 months.

 

[fgonz]

how do i perform a no drain acid wash? would this be an effective option in an attempt to remove calcium scaling on 7 month old plaster?

 

[JasonLion]

When the scaling is localized, which it sounds like your is, you don't want to do a no drain acid wash, as it will damage the plaster everywhere that there isn't scaling. If it is very localized, you can use a PVC pipe to direct acid directly to the spots that are stained/scaled, though this gets very tedious if the scaling is more extensive.

With CH at 500, it doesn't take too much inattention for the PH to go up, which can sometime result in scaling, even if the periods of high PH are very short.

 

[fgonz]

what do you recommend? i am leaning towards draining pool to remove high CH. Plaster is fairly new and worried about any acid wash treatment causing more damage than good.