Scaling Issue?

[SLEJ]

Hi, I'm new to this forum and new to pool ownership.

We had our pool built in mid Sept 2009 and had roughness in our hot tub from the beginning (as far as we know), which is connected to the pool. We have gray plaster in the pool and hot tub. We have spent the last two years trying to get the pool builder to warranty the plaster, and they just came back and said it's a scaling problem which is not covered in the warranty.

My question is, can scaling occur just in the hot tub and not anywhere else in the pool? The water return does go to the pool and the hot tub, so any chemical that I put in the pool (muriatic, chlorine, etc.) will go to the hot tub too. If it's possible that the hot tub gets scales and the pool doesn't, is it possible that the scaling only occur about 7 inched below the coping in the hot tub?

I would think that if I have scaling it issues in the hot tub, all the plaster in the hot tub would be affected. However, when I work my hand all the way around the hot tub, the plaster all smooth until I get down to about 7 inches from the coping, then it's really rough.

This is possible or is the builder trying not to honor they warranty?

We really haven’t had a chance to enjoy the hot tub because it’s too rough/sharp to sit in. Thanks in advance for your input.

[czechmate]

Have an experienced pool builder to look at the surface of the spa. Scalling on the gray surface is easy to tell. Pitting or corrosion by lack of calcium also.
The hot tub may have been lightly acid washed during plaster finish and not well washed of with fresh water.

[SLEJ]

Yeah, I was thinking about getting a third party to do the assessment, just for my sanity.

Does anybody know of a good person for this in the Northern Virginia area?

[chem geek]

You can most certainly have scale in the spa and not in the pool because the spa is at a higher temperature than the pool. Going from 80ºF to 104ºF raises the saturation index by about 0.2 units. Also, the aerating jets in the spa can raise the pH substantially, especially if your TA is already high so that can increase the saturation index even more, perhaps by 0.5 or more (e.g. from a pH of 7.5 in the pool to 8.0 in the spa).

[SLEJ]

That makes sense, thanks. The question is, then, do I treat my spa differently than my pool? They are both connected.

[czechmate]

You can not treat spa on its own.
It is common water with the main body. I would not heat it much over
90F since it is not needed for comfort, specially if you consume alkohol.
Further, plaster in the spa may suffer if you have calcite saturation index on the problem border.

[SLEJ]

Ok, thanks all for your help.