Scale Buildup with Low CH

[starman314]

Hi,

I am just learning how to balance the chemicals properly in my pool and would appreciate some help. Here's the info for my 46K gallon SWG pool:

FC: 8.5
pH: 7.4
TA: 100
CH: 150
CYA: 60
SALT: 2200
CSA: -0.52

I am working on bringing the FC level down to 4 and am planning to add 400lbs of salt to address the issue with the salt level.

The CH level appears low as well. However, we appear to have a significant amount of scale buildup along the deep end tile under a raised stone wall that borders the pool (see attached photo) and along the tanning ledge tile. Should we go ahead and raise the CH level to ~350-400 regardless? I'm assuming we would do that by adding calcium chloride (~100lbs) or calcium chloride dihydrate (~140lbs)?

If the CH level is low, why are we getting scale buildup? How do we get rid of the scale on the pool wall and prevent it from coming back?

 

[JamesW]

That's efflorescence from water coming through the wall from behind.

It's not related to the water chemistry.

If you have water features in the wall, there might be a leaky pipe.

Otherwise, the water is probably rain water that builds up and seeps through the wall.

Changing your water chemistry won't make any difference.

However, if you have a plaster pool, you should maintain the CSI between -0.3 and 0.0 to protect the plaster from corrosion.

 

[starman314]

That's efflorescence from water coming through the wall from behind.

It's not related to the water chemistry.

If you have water features in the wall, there might be a leaky pipe.

Otherwise, the water is probably rain water that builds up and seeps through the wall.

Changing your water chemistry won't make any difference.

However, if you have a plaster pool, you should maintain the CSI between -0.3 and 0.0 to protect the plaster from corrosion.

Thanks. This is helpful!

Would we remove the efflorescence using Muriatic acid like we would with scale?

Is there anything we can do to prevent or mitigate the issue in the future? Would a sealer on the tile help?

 

[JamesW]

Muriatic acid would probably work.

Test a small spot to see if it's safe. Maybe use a toothbrush and acid.

You probably need better drainage behind the wall.

Is that a water feature in the wall?

If yes, the plumbing going to it might be leaking.

The next time you run the water feature, watch for damp spots near the efflorescence.

Sealer might help some, but maybe not a lot.