JRM75 Posted July 23, 2008 Report Share Posted July 23, 2008 I have a 11,000 gallon pool, It runs on a sand filter 17 hours a day. The return jets are manually placed upwards to move water-surface-debris and dirt to the skimmer. It is a pool that uses chlorine and sodium tetraborate (8 pounds a month). These are my weekly Pool water chemistry statistics: PH: varies each week, but the average is 7.688. This week it is 7.092 Free Chlorine: approximately 4ppm constantly Total Alkalinity: approx. 70 ppm (varies each week as well at about -20ppm to +20ppm) Cyanuric Acid: approx. 10.2 PPM constantly Calcium Hardness: 125.9 ppm I put 48 ounces of 51% sulfuric acid (diluted) weekly to balance out the PH rise from my chlorine in my pool. I also add 8 pounds of 20 mule Team BORAX once a month. I brush/vacuum the pool and backwash/rinse the filter weekly. Every 6 months I dump 50 pounds of Calcium Chloride in my pool to balance/increase hardness. I use chlorine-free shock and superchlorinate Bi-weekly. My pool's fiber glass is etching away, I have metal stains on floor+walls, and my pool's floor/wall paint is degrading very quickly for some reason. There are also some black smudges like hand prints on my fiberglass paint, which cannot be brushed off (even if I use ascrobic acid) My Pool isn't cloudy and it's pretty crystal clear as of now. But, How can I improve on the etching away of the fiberglass? Quote Link to comment Share on other sites More sharing options...
chem geek Posted July 23, 2008 Report Share Posted July 23, 2008 I don't understand your chemical regimen. Why are you adding 8 pounds of 20 Mule Team Borax once a month? That will significantly raise the pH unless you are adding acid at the same time and it will add 10 ppm to Borates every month which seems higher than any dilution from backwashing would justify. 50 pounds of Calcium Chloride would raise the Calcium Hardness (CH) by 491 ppm unless you are using the dihydrate form which would raise the CH by 371 ppm. This seems high though your current CH is at 126 ppm. Perhaps your backwashing volume is high. What source of chlorine are you using? Chlorinating liquid or bleach or Trichlor tabs/pucks? Non-chlorine shock as well as your sulfuric acid adds to sulfates and that could be causing problems with your fiberglass at high levels. You should not need to use non-chlorine shock nor need to superchlorinate if you are maintaining appropriate Free Chlorine (FC) levels relative to your Cyanuric Acid (CYA) level. Your CYA level also seems low. It seems to me that you are massively swinging your chemical balance, including the pH, and building up sulfates and borates significantly. I would also get your own good Taylor K-2006 or TF100 test kit since I wouldn't trust the numbers you are getting (are they from a pool store)? Was it the pool store giving you advice of using acid and borax? Richard Quote Link to comment Share on other sites More sharing options...
JRM75 Posted July 23, 2008 Author Report Share Posted July 23, 2008 I don't understand your chemical regimen. Why are you adding 8 pounds of 20 Mule Team Borax once a month? That will significantly raise the pH unless you are adding acid at the same time and it will add 10 ppm to Borates every month which seems higher than any dilution from backwashing would justify. 50 pounds of Calcium Chloride would raise the Calcium Hardness (CH) by 491 ppm unless you are using the dihydrate form which would raise the CH by 371 ppm. This seems high though your current CH is at 126 ppm. Perhaps your backwashing volume is high. What source of chlorine are you using? Chlorinating liquid or bleach or Trichlor tabs/pucks? Non-chlorine shock as well as your sulfuric acid adds to sulfates and that could be causing problems with your fiberglass at high levels. You should not need to use non-chlorine shock nor need to superchlorinate if you are maintaining appropriate Free Chlorine (FC) levels relative to your Cyanuric Acid (CYA) level. Your CYA level also seems low. It seems to me that you are massively swinging your chemical balance, including the pH, and building up sulfates and borates significantly. I would also get your own good Taylor K-2006 or TF100 test kit since I wouldn't trust the numbers you are getting (are they from a pool store)? Was it the pool store giving you advice of using acid and borax? Richard 1) I'm using sodium tetraborate as an alternative to my chlorine stabilizer, which reduces chlorine consumption (Even if UV rays eliminate them), plus it reduces algae growth and seems to make my water look more sparkly. 2) the calcium chloride I'm using says that it will only raise my calcium hardness to 400ppm, but I didin't mean that I dump it in one go (during the sixth month period I split between 25 pounds per 3 months, usually before the spring and summer months as I don't need to backwash as often) 3) I'm using liquid chlorine, and use up one jug per week. Even I sometimes have free chlorine in the pool it smells like there's always chloramines for some reason, that's why I superchlorinate and use one pound of shock (Potassium Monopersulfate) bi-weekly. 4) for the CYA levels, well it's pretty self-explanatory for the borates are the ones reducing the chlorine consumption in my pool, but usually I dump 9 pounds of cyunaric acid every 3 months to reach 120 ppm (although the ppm is high, but that's what my pool store recommends) 5) The readings/numbers for the chemicals in my pool are shown to me at my pool store when they test my water (they use a drop test or something that uses liquid,etc. testing). 6) the pool store also tells me that I should atleast add 64 ounces of acid every month and borax ( 2lbs per 10,000 gallons) if i want to be cheap about stabilizer, sodium bicarbonate, and algaecide. Quote Link to comment Share on other sites More sharing options...
Aussie Pool Guy Posted August 13, 2008 Report Share Posted August 13, 2008 I have a 11,000 gallon pool, It runs on a sand filter 17 hours a day. The return jets are manually placed upwards to move water-surface-debris and dirt to the skimmer. It is a pool that uses chlorine and sodium tetraborate (8 pounds a month). These are my weekly Pool water chemistry statistics: PH: varies each week, but the average is 7.688. This week it is 7.092 Free Chlorine: approximately 4ppm constantly Total Alkalinity: approx. 70 ppm (varies each week as well at about -20ppm to +20ppm) Cyanuric Acid: approx. 10.2 PPM constantly Calcium Hardness: 125.9 ppm I put 48 ounces of 51% sulfuric acid (diluted) weekly to balance out the PH rise from my chlorine in my pool. I also add 8 pounds of 20 mule Team BORAX once a month. I brush/vacuum the pool and backwash/rinse the filter weekly. Every 6 months I dump 50 pounds of Calcium Chloride in my pool to balance/increase hardness. I use chlorine-free shock and superchlorinate Bi-weekly. My pool's fiber glass is etching away, I have metal stains on floor+walls, and my pool's floor/wall paint is degrading very quickly for some reason. There are also some black smudges like hand prints on my fiberglass paint, which cannot be brushed off (even if I use ascrobic acid) My Pool isn't cloudy and it's pretty crystal clear as of now. But, How can I improve on the etching away of the fiberglass? High levels of calcium will be one of the main reasons for your fibreglass to be coming away as well as the sulfuric acid you are mixing into your water try a 13 to 1 mix of hydrochloric acid to water and only add 600ml (apologies for the metric units) a week that will lower both calcium hardness and ph and hopefully balance it. One would ask why you are using a chlorine free shock and superchlorinating it? Quote Link to comment Share on other sites More sharing options...
chem geek Posted August 13, 2008 Report Share Posted August 13, 2008 The sodium tetraborate does not perform the same function as Cyanuric Acid (chlorine stabilizer). It is a base that makes the pH rise and in larger quantities is an algaecide. Adding a little doesn't help -- getting to 50 ppm Borates is what is needed, but that is a lot of Borax AND acid added one after the other in batches -- or you can get Proteam Supreme Plus which is pH balanced (it's mostly Boric Acid). Once you get to the 50 ppm Borates level, you don't need to add more except to replace that lost from splash-out and backwashing or other dilution. 120 ppm CYA is too high unless you keep the Free Chlorine (FC) level at a minimum of 9 ppm. The pool store is wrong about the CYA level, but they are right about you using chlorinating liquid (or unscented bleach) since that prevents CYA from continuing to climb. If you want to keep the chlorine from getting used up as quickly, then you can have around 80 ppm CYA and keep a minimum of about 6 ppm FC, but you'll still probably need to add chlorine about twice a week getting it to around 10-12 ppm FC and so it drops not lower than 6 ppm in 3-4 days. I suggest you get your own test kit, the Taylor K-2006 you can get at a good online price here or the TF100 from tftestkits.com here with the latter kit having 36% more volume of reagents so is comparably priced "per test". You can also get LaMotte Borate test strips to test the Borates level. Richard Quote Link to comment Share on other sites More sharing options...
Jenine Lande Posted August 23, 2011 Report Share Posted August 23, 2011 Adding on to JRM75's comment, a test kit would probably be your best bet, they're priced depending on your pool routine and extremely convenient and at your reach when you need it. You can find it at a local family leisure pool supplies store and such. Not neglecting this routine and doing it periodically could help your fiberglass from etching away. Quote Link to comment Share on other sites More sharing options...
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