I have a 40,000 gallon vinyl lined inground pool. I am having a few issues that I am trying to resolve.
Cl levels are 2-4 ppm. I just addded 26 lbs of sodium bicarbonate in an attempt to raise pH...it's still below 6.4. (The alkalinity is correspondingly low).
The cyanuric acid is also zero. I have staining (light brownish rust color) on the plastic steps, returns and portions of skimmer covers that are under the water. I have a sand filter.
After reading your story I can see I need to get some stabilizer/conditioner (cyanuric acid) in pool, but what abour pH? Do I just keep adding more baking soda until pH is at proper levels?
Thanks for the question Larry
There are two things you can do right now. First is to raise the TA. That needs to be between 80 - 100ppm. Use 2.5lbs. of baking soda per 20,000 gallons to raise the TA 10ppm. Pump off, add it into the deep end and let it sit for 3 - 4 hours. Pump back on FILTER for 8- 10 hours, then retest and make another adjustment.
After you turn the pump back on FILTER, you can shock the pool using Dichlor chlorine. This is a stabilized form of chlorine. Once you reach the 30 - 35ppm CYA mark, stop with Dichlor and go back to regular liquid chlorine. Proper range for CYA is 30 - 50ppm.
Be careful when using Dichlor as it can get out of hand quickly. For every 10ppm of chlorine added with Dichlor, you'll raise the CYA by 9ppm. For every 10ppm of chlorine added with Trichlor tabs you'll raise the CYA by 6ppm.
Do these two steps morning and evening until the desired levels are met. Test the TA, pH, chlorine, and CYA.
Next is to raise the pH. It's 2.5 lbs. of bicarb to raise the pH 0.2
per 20,000 gallons. Broadcast this around the perimeter of the pool with the pump on FILTER. Sweep very well.
You need to figure out the kind of staining the pool has. It could be either organic or metal. Take a chlorine tab and put it on the stain for 5 - 10 minutes. If it fades it's organic and you'll need to shock the pool. If the stain doesn't fade or goes black, it's probably metal.
To confirm this, get some ascorbic acid (crushed up Vitamin C) and put it in an old sock or pantyhose and place it on the stain. If it fades, it metal and you need to do an ascorbic acid treatment. Details for the treatment are here:
If you have high metal in your water, you'll need to manually dose your pool with the metal sequestrant. Metal sequestrants that are based on HEDP, phosphonic acid and/or its derivatives are the most effective.
Some popular brands are Jack's Magic Blue, Purple, and Pink Pink Stuff, Metal Magic, Metal Free, & Metal Klear.
This is normally not a one shot deal. A metal sequestrant does not remove metal from pool water. It holds it in solution until it can get filtered. Then you backwash the metal out.
Because metal sequestrants break down over time and get filtered and backwashed out, you will need to add a bottle once per week.
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