Removed calcium deposits but still have lines left

[Larry Lizard]

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Converted to TFPC a month ago and yesterday tried removing calcium deposits around the spa spillways. Using diluted (4:1) MA and a plastic scrub brush it all came off except for the lines you see on both sides of each spillway. Repeated applications of the acid did nothing to remove it - no fizzing at all. I tried again today and still no reaction even though my mixture still worked on areas I haven't gotten to yet. The lines are where the top edge of the buildups were and they have a slightly rough texture. Could something have leached out from the edge of the tiles (grout or mastic maybe) inside the spillways or the spa itself?

I was thinking about getting a "Magic Eraser" or some such thing, but thought I'd ask for ideas first.

Results of today's test:
FC - 7.0
CC - 0.5
pH - 7.6
TA - 90
CH - 170
CYA - 60
Converting to TFPC we drained about half of the water to get the stabilizer down, then added calcium. Pool Math shows my CSI at -0.08 currently, which I can live with.

Leslie's Pool test back on the 7th of June:
FC - 2.0
TC - 2.0
pH - 7.4
TA - 70
CH - 275
CYA - 100 (their max - it was still 70 after draining).
Assuming CYA was about 140 the CSI with these numbers would have been -0.51.

 

[pooldv]

Yes, you can try a magic eraser or scrape them with a razor blade or a stronger acid mixture. Yes, that's a good CSI number. Between -0.3 and +0.3 is ideal.

 

[Larry Lizard]

Was finally able to get back to the job this morning.

A 3:1 MA mix still didn't work, so I tried a window scraper that holds a single-edge razor blade. It worked surprising well but our tile isn't flat:

so it wouldn't get the low areas. I tried some 320 grit wet/dry sandpaper and that took it off nicely.

Thanks for your time, neighbor.

 

[pooldv]

Good deal. Nice tip on the wet/dry sandpaper.