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Sorry if this is kind of a silly question, but could someone please tell me what I should keep all of my numbers at in a fiberglass pool? I have a Taylor test kit and try to keep those recommended numbers, but now I wonder if fiberglass has some different requirements. Thanks.
Tisha
fiberglass pools have a basically non reactive surface so water balancing is a bit easier. Generally the numbers used for a plaster pool are appropriate. There is some question on how much calcium, if any is needed for fiberglass but there seems to be some evidence that maintaining at least a 150 ppm calcium hardness can help prevent staining and 'cobalt spotting' (cobalt leaching out of the gelcoat.
Thanks, Evan. Is cobalting the same thing as blistering?
Tisha
not really. cobalt staining looks like little black or dark grey dots that get bigger and sometimes have a brownish ring around them.
Evan's right. Central target numbers on pools are safe on all chlorine-based pools (I know little about bromine and other non-chlorine pools).
The main reasons we tell people to follow different numbers for Calcium and Total Alkalinity on vinyl pools is:
1) Cost savings
2) Swings in measurements.
For example: a Concrete or plastered pool should have a calcium level of 200 to 400ppm
But your F/G pool needs less, and a vinyl pool doesn't really need any--so why should a vinyl pool owner spend $40 adding calcium that isn't needed?
Total Alk is touchier in concrete/plaster pools--125ppm is the max recommended level. But in vinyl (and probably in F/G) you can safely go to 180, and only at 200ppm should you ACTIVELY lower T/A.
Vinyl pools, however, are FAR more sensitive to low pH--it can damage the vinyl shortening its life. So if I had a concrete pool and pH was 6, I wouldn't worry, I'd just raise it. But in a vinyl pool I'd be dumping in boxes of Borax RIGHT NOW! (so my vinyl doesn't melt).
Finally, there's the numbers for SWGs. They aren't QUITE the same, but that's for a different thread!;)
Thanks guys. I love this forum.