Help/advice with recent calcium deposits/flakes in pool

[CajunGuy]

Recently, I had to perform a short slam (for about a week) on my pool due to noticing a few small spots of algae. It was caused by a pool party for my daughter's birthday (about 20 kids in the pool) and combined with the extreme temps here (over 100 with heat index right now) it caused a small outbreak. I noticed it quickly though and got to slamming/scrubbing and immediately and took care of it...eventually passing criteria for OCLT.

Anyways, towards the end of the slam I began noticing a good bit of calcium flakes/deposits coming from the pool returns settling around the bottom edges of the pool. I've been cleaning it up daily, but it shows up again the next day. I recently had cleaned the salt cell about a week ago, so I walked over and noticed it already had a small amount of buildup between the plates. During the slam I boosted my salt cell production a few times to 100% to assist in getting FC up to where it needed to be. I was also using liquid chlorine throughout the entire slam. I also used two 1 lb packs of Burnout 73 (1 pack each night for 2 nights in a row in the middle of the slam). Prior to the slam, my CH was around 350...which is what is recommended for a gunite SW pool.

The odd thing is that I've NEVER really had a problem with calcium flakes entering my pool from my salt cell reversing polarity and "cleaning" itself. This was the first time this has ever really happened. My most recent test results from yesterday with my Taylor K2006 kit are as followed:

FC 5
CC 0
TA 110
pH 7.6
CYA - unable to check, but was around 80 last time it was checked about 2 weeks ago
CH - unable to check because I ran out of the hardness reagent, but it was 350ish about 2 weeks ago

What do you guys think is all of a sudden causing all the calcium flakes from the salt cell? I've read that a high TA may cause increase in calcium deposits from salt cell...not sure if this is true? Could it have been from ramping up my salt cell production to 100% a few times during the recent slam?

I was going to try and lower the TA to around 80 and see if it helps reduce the calcium flakes/deposits. I am very diligent in keeping my pH in check, so it never really gets above 7.8 and I don't have any calcium buildup around my pool's tile line.

Any helps or advice is greatly appreciated...thanks!

 

[rfrank1515]

I get this from my salt system when the PH is to high.

I wouldn’t think 7.8 would be too high but worth trying to lower a tad see if the symptoms change.

 

[mknauss]

To minimize the scale build up in your SWCG and the calcium flaking in your returns, keep CSI between -0.3 and 0. Based on your data above your CSI is just over 0 using a guess on salinity and water temperature.

Your observation of reducing your TA is correct. Lowering it to 80 (or a bit lower) will put your CSI in a good spot.

 

[jblizzle]

It is "high" CSI that will allow the calcium flakes to develop in the SWG.
You want to keep your CSI in the -0.3 to -0.1 range to prevent it.
I am guessing that with the SLAM, your pH was higher that normal and allow the scaling to start in the cell as well as the fact that you were running the cell more.

 

[CajunGuy]

To minimize the scale build up in your SWCG and the calcium flaking in your returns, keep CSI between -0.3 and 0. Based on your data above your CSI is just over 0 using a guess on salinity and water temperature.

Your observation of reducing your TA is correct. Lowering it to 80 (or a bit lower) will put your CSI in a good spot.

Ok, I'll lower it and shoot for 80. I have all 3 waterfalls on right now to help increase aeration and pH. I'll knock it back down to around 7.2-7.4ish every few days when it rises and then I'll recheck TA soon. I also clean the salt cell again when I get the chance. I have some hardness reagent that should be delivered this weekend, so I'll be able to update an accurate CH level too. Thanks for the advice!

- - - Updated - - -

It is "high" CSI that will allow the calcium flakes to develop in the SWG.
You want to keep your CSI in the -0.3 to -0.1 range to prevent it.
I am guessing that with the SLAM, your pH was higher that normal and allow the scaling to start in the cell as well as the fact that you were running the cell more.

So even thought I routinely keep my pH in check (it's always somewhere between 7.4 and 7.8) and I have no calcium buildup on my tile at the waterline...I can still get calcium deposits from the salt cell due to a high CSI?

I'm gonna try lowering my TA over the next few days/week and see if that helps as mentioned above.

 

[jblizzle]

Yes, because the environment within the cell is more alkaline and scale will happen there before on your pool.