I have a fibreglass pool that has spots no bigger that the head of a pin on the bottom and steps of a pool.....have tried vitamin C along with Bioguards product, metal free and stain free, ....nothing touches it
water balance is correct
any suggestions??
thnaks
dg
Comments
hi dennis,
the spots may be what is sometimes called "cobalting spots". some of the symptoms of that are possibly a tiny deposit, whether hard or oily. they usually appear in the immediate vicinity of a 'blister', and can even have a slight "smoke trail" going off in the direction of the water flow in the area. if this is 'cobalting', it can be temporarily cleaned up with a product sprinkled directly on the stain called "cobalt cure" by united chemical. they have a web site for sales (www.http://easypoolsupply.com), and i found the product at SCP. the main ingredient is oxalic acid, but joc hamilton made an enhanced formulation that has worked really well for me over the years. only problem is, there is no cure, only a temporary cosmetic clean up. cobalt spots (still not really knowing if that is what you have..but a picture might help) are caused by water that migrates through the glass and finds a concentration of cobalt salts, and then collects forming a blister which finally breaks back through the glass and weeps that liquified deposit. so solutions to the problem are too cost prohibitive to consider except in well financed situations. ;-) so i would agree with the last two comments!!
As tiny, invisible "pinholes" develop in thinner, older gel-coat, water and pool chemicals can react with cobalt in the fiberglass mixture to form a cobalt crystal. The appearance of these crystals has nothing to do with the pool cleanliness, sanitizers used, or other water chemistry. It is strictly related to the materials in the fiberglass.Once cobalt spots start forming, they become noticeable as a dark brown or black, pinhead sized crystals. The crystals slowly grow. A "rust" ring develops around them. If the crystal is on a vertical wall of the pool, then the ring streaks ½" to 1" down from the crystal.The crystals can be scraped off with a butter knife or a putty knife. The "rust" ring can be removed with a rubbing compound, or with a mild Muriatic acid/water solution (1 part acid to 10 parts water).Ascorbic Acid or vitamin "C" can be used as an acidic reducing agent in the removal of difficult metallic stains, like cobalt, from underwater surfaces.Commercial preparations like Cobalt Cure are specifically formulated for this problem. They can be very effective in the treatment of cobalt spots. These chemicals can be used in maintenance doses to prevent further buildup. If the problem is especially severe, standard chelating agents may also help.
Only remaining possibility is cobalting. It's caused by airholes in the swimming pool gel coat when it was applied.
This usually takes 20 or more years to occur. Unless, of course, you bought from a company that advertises "buy manufacturer direct". With those pools, it occurs in less than 5 years, along with many other problems that occur during the same time frame.
If you purchased from that manufacturer, then it is cobalt, and the only solution is to remove the so called "swimming pool gel coat". Then replace it with real swimming pool gel coat.
1st, this only applies if these are stains you're trying to remove but treatments don't work. Test the TDS and Stabilizer readings, if high to very high the sequestriants for stain removal are being limited by the TDS readings or over 100 stabilizer readings. Drain 2/3 of pool, dilution is the solution.
Thanks Rob M
I tried that approach but no good.......I've tried Natural Chemistry but that didn't work...Bio Guard has a product called "off the wall" that is my next adventure
thanks
dg