How do you know how much bleach you need to shock the pool? I have an octagon vinyl pool. About 16000 gal. Thanks for the info.
Shannonpb2 said:back washed to dump as much water as I could (not a whole lot) and put the water hose in. I dont know what good it will do. I cant use too much water. I have put 6 boxes of borax in over the day. The only thing that is happening is the water is getting cloudy. The PH has not budged. Should I put some more algaecide in? When i just did the test the color of the chlorine side was very light yellow (this AM was bright yellow). Any suggestions are appreciated.
Another question. Just curious: on print out from pool company is said my CYA is 100, But in the "ideal" column it list the CYA should be 30-200. What is the real "ideal" number I should shoot for?
chem geek said:I agree that it is important to know the true Total Alkalinity (TA) number. If it's really 10 (and not 100), then using a pH Up product would be the way to go to get the pH up since it will also increase the TA as well. pH Up is identical to Arm & Hammer Super Washing Soda (careful: not the laundry detergent) in case you wanted to get the store product instead (it's usually cheaper) and is also known as Soda Ash or Sodium Carbonate. If I assume the pH is 6.2 and the TA is 10, then for 16,000 gallons adding 6.6 pounds (about 11-1/2 cups) of pH Up / Soda Ash / Arm & Hammer Washing Soda will raise the pH to 7.5 and the TA to 57. I'd suggest adding about half that amount, wait an hour, then retest the pH to see where you are at. If the pH registers around 6.9, then add the second half (if it's higher, then report back and we'll let you know how much less to add).
Since you already bought 20 Mule Team Borax, then you can use that instead and it will take about twice as much by weight, so around 13.2 pounds (about 25 cups or almost 3 boxes since each weighs 76 ounces) of Borax to raise the pH to 7.5. Again, add about half the required amount and retest the pH after an hour to see where you stand. The Borax will raise the TA to around 35 ppm (if you added the full amount) so you can later add some Baking Soda to increase the TA further (about 15 cups of Baking Soda will increase the TA from 35 to 78 and will also raise the pH some to 7.64).
I suspect that you were using Trichlor tabs/pucks and that got the pH and TA low due to its high acidity. This would also explain the high CYA level since with Trichlor for every 10 ppm FC that they add, they also increase CYA by 6 ppm.
Richard
waterbear said:You have been using trichlor tabs and have not monitored your pH OR TA, correct? This is how you ended up with low pH and no measurable TA (all the bicarbonate has been converted to carbonic acid) I would go to the grocery store and get some Arm and Hammer Super Washing Soda from the Laundry aisle. It will raise your pH AND TA rather quickly. You will need about 1/2 the amount of this compared to the amount of borax you need. My suggestion would be to first take a deep breath.
Now add two lbs of the washing soda (btw, this is EXACTLY the same as pH increaser. It is also called soda ash or Sal Soda.) Wait about 1 hour with the pump running and test your pH. If it's still below 7.0 add another two lbs, wait about an hour and test again. Once you get your pH above 7.0 test your TA. You will need MUCH LESS of the washing soda than if you use borax and baking soda. THIS is the one case where washing soda (or pH increaser) IS the proper choice.
for testing the pH do not use strips, If you don't have a good test kit then get a cheap 2 way drop test for about $7. It will be your best choice for monitoring the pH right now.
Once you get the pH inline then we can tackle the rest.