Staining? Mottling?

[censored]

Hey all, now that I have trouble free water, I want to start working on my staining. Kim and I started diagnosing this in my original thread which was geared toward my swamp, but now that my water is clear I would prefer to have a separate discussion geared to this.

So this is what my pool looks like:

Kim had me try the vitamin C test and here are my results:

The first is before. The second is after. It looks like the vitamin C ate through the center a little on the second pic. I tried a trichlor tab and no change.

Also a couple weeks ago I tried the vitamin C test but actually rubbed the tab onto the stain:

Thinking the white was just the powder from the pill being sanded down, I didn't really count that as anything but 2 weeks later it is still white... I would think the powder would have dissolved by now if the white was just vitamin residue.

So my thoughts and Kim's thoughts are it is worth a try to do an ascorbic acid treatment, so I went out and got 4 pounds, a sequesterant (Metal Free from Leslie's), and a 4.0 CULator. I haven't used them yet because my FC is still high from SLAM, but I thought I would try some of the ascorbic acid in a sock on the stain in the meantime... well that provided no change.

Thinking maybe acid wash, I tried a little in a PVC pipe right on one of the deeper stains, but that had no effect other than some faint black streaking down to the drain.

I had a plaster guy out here today and he said there is nothing that can be done short of replastering (of course he would say that) but I am starting to wonder if that is indeed true.

He also mentioned that the pool is supposed to be the grey color, not the beige or white.

I believe the plaster is close to 20 years old but other than this appears to be in good shape. Because of the age a local acid wash guy said he would not acid wash it.

Any thoughts?

Thanks.

 

[Patrick_B]

In this case, I think it's unlikely the results of an acid treatment will be satisfactory. It's pure speculation, but this is pretty extreme. As for doing one on a finish this old, I really don't know, but it may be risky. If you're prepared to go through a re-finish soon, I guess you can try, but I really think any benfit will be minimal. Sorry I can't add more than speculation, but you've probably come to about the same conclusions. Any chance of a re-do in the near future?

 

[duraleigh]

Yeah, I am with patrick_B. From the pics, it simply looks too extreme to hope an acid wash will do much.

I do think it will improve the look, perhaps, but not enough to make a significant difference.

This is all speculation so., if it were my pool, I think I would do the AA anyway just to see what happens.

You might also consider a long-term project of holding your pH down quite low (7.0) to see if that will remove some of the scale.

Your water looks great! Nice work!

 

[pooldv]

Agreed that the plaster is too old and the risks outweigh the benefits. I would hold the PH low, it might help some. Keep your CSI -0.2 to -0.4. Use Poolmath the tweak PH and TA to adjust your CSI. Keeping your CSI negative might help some and it will help you get as much life out of the existing plaster before you refinish it.

If you want to read more about it there is more here
Pool School - Calcium Scaling

and here
Langelier and Calcite Saturation Indices (LSI and CSI)

 

[censored]

Thanks for the replies. Looks like everyone is on the same page, skip the acid wash and try the AA but don't expect much. I just got the got the quote back from the re-surfacer. $4,900 for Diamond Brite -- seems reasonable enough to me. I probably won't do it this year since we just committed to solar, but hopefully before next season. I will probably just skip taking the PH out of balance and enjoy the swim season and hope for some good commissions to get the resurface There are no dangers of swimming like this are there?

And Dave, thanks for the compliment on the water, I owe it all to TFP!!!!!!!

 

[pooldv]

No danger at all, swim away. Your only issue is if/when it starts leaking.