Saltwater Pool, High TA and high CH - White flakes, Need some advise

[jwigginton]

Hello,

I'm new to the forum and just started testing the pool myself. I have been using the local pool stores for the past 4 months, but noticed some white flakes all over the bottom of the pool and so I order a K2006 Test kit to take things under control myself.

The pool color is nice, typically i've had to add about a quart of Muratic Acid every week or so to lower the pH, some stabilizer, etc. One time the pool store had me add 7lb of calcium hardness and I think that is what caused my issues, but looking for some advise. My readings are as follows:

FC - 1
CC -.5
PH 7.8
TA - 160
CH - 600-650
CYA - 60

I wasn't sure what the white flakes that settle on the bottom were, wasn't sure if it was left over stabilizer that didn't dissolve or the calcium hardness that I added. I purchased the Dolphin robot with the fine filters and it vacuums it all up, but it does come back, so it's not a one time thing, but I think Calcium scaling?

The pool is new (4 months).

Today, I put in enough acid to drop the PH to 7.0, but not sure how I'm going to try an aerate the pool. Any tips on that? Also based on the CH, do I need to drain some of the pool to get it back in order? If so, any easy way to do that?

Thanks for any tips or advise.

Regards,
Josh

 

[Jimrahbe]

Josh,

Welcome to TFP... A Great resource for all your pool questions...

I had the same thing happen to me when I added too much Calcium-up to my pool. The flakes went away in a week or so...

When my robot vacuumed it up it was more like toothpaste. I put some on a plate and add a few drops of Muriatic Acid (MA) and it bubbled like crazy, confirming it was Calcium.

I cleaned out my SWCG, which was about a year and a half old, and it had some, but not a lot of buildup..

An FC of zero or 1 is never a good thing. With a CYA level of 60 your very very minimum FC level is 3 ppm and you really should be shooting for at least 5 and I'd make it 6 or 7 ppm to be on the safe side. See this chart... https://www.troublefreepool.com/content/128-chlorine-cya-chart-slam-shock

I suggest you try lowering your TA, which would help you maintain your pH better. I would try to keep the pH between 7.7 and 7.8 with SWCG pool as it will be much easier. See this article about lowering TA... https://www.troublefreepool.com/content/129-how-to-lower-lowering-total-alkalinity

Thanks for posting,

Jim R.

 

[jwigginton]

Thanks for the tips. I'm not sure how my FC got so low, I'm going to boost my SWG to 60%, it's been at 40% and I've been told to boost it once a month or every other month. I'll see if 60% makes a difference in the next week or so. Thanks for the tip on the MA on the white flakes to validate it's calcium. I have cleaned my SWCG. There wasn't a much buildup on the cells. I'll look into lowering the TA.

 

[chiefwej]

I have both high TA and high CH in my fill water and the added problem of extremely high evaporation rates. I recently went through two full pool seasons with a CH over 1,000 with no scale. As you are already learning, lowering the TA with acid and aeration will help stabilize your pH. But The real key to avoiding scale is to carefully monitor your CSI. Put all your test results into PoolMath and it will give you your CSI. To avoid scale you should try to maintain a slight negative CSI. I shoot for somewhere between -0.10 and -0.30. As CH levels rise it becomes increasingly more and more difficult to keep it within that range. Eventually it's like walking a tightrope and then you drain, refill and start over.

 

[jwigginton]

Thanks for the tip on the CSI. From playing with the numbers I do see if I can keep my TA low with a lower ph and some other items, I can get a negative CSI. It's currently at +0.58.

I'm also thinking of just having the hose fill the pool and since I have an overflow it would slowly replace the existing water until I get a decent CH? Is that a bad idea? I'd need to test the water coming out of the spigot to see it's CH and TA, but I can rebalance the other chemicals ok once i get the CH down. Thoughts?

 

[chiefwej]

A 600 CH is manageable. But if your tap water is much lower (say 250-300) changing out some water will definitely make it easier. You will get the biggest advantage by doing larger changes. Say like a 50% drain and fill. A slow overfill program would take much longer and require much more water to yield the same result.

A CSI of +.58 and a SWG is the reason you have scale. PoolMath shows the danger point for scale at +.60 and the danger for plaster damage at -.60. If your CSI measures +.58 in the pool, I can assure you that is much higher inside the salt cell where your chlorine (and scale) are being produced. In fact that's why you need to keep the CSI lower in a SWG pool than you would in an ordinary liquid chlorine maintained pool.