Hello and welcome! We are glad you found us and thank you for becoming a subscriber. Some pools open in the spring with a high chlorine demand that you think is never gonna end and then one day it does. The answer is to keep shocking the pool and keep the chlorine consistently high. How high your chlorine needs to be depends on your CYA level. Since yours is 70, then you need to shock it up to 20. Test as many times a day as you can and each time add enough bleach to get back to 20. There is no such thing as testing/dosing with bleach too much. The more often, the faster you'll be done. In a pool this size, each quart of 6% bleach will add about 1.2ppm of chlorine. Once you get the chlorine level to hold overnight without losing more than 1ppm of chlorine, then you can let the cl level drift down. With a CYA of 70, you'll need to keep your chlorine between 5-10 all the time or you'll risk an algae bloom. Don't use any trichlor pucks or dichlor shock powder as these are both stabilized and will cause your CYA to continue to rise, and you don't want that! Just stick with bleach.
You're going to need to get a good test kit. Cheap test kits cannot measure chlorine levels as high as you are going to need to run. We recommend the Taylor K-2006 or 2006C which you can find in the Amazon link in my signature line. If you buy through the link, the Pool Forum makes a little money on the sale which helps us to keep this place going. Until you get the good kit, you can use a dilution method. Not super accurate, but better than nothing until that good test kit is in your hands. More about that here:
http://www.poolsolutions.com/gd/how-...d-testkit.html
Another issue that you have is that you need to get that pH up above 7.0 ASAP! Any reading below that is acidic and can damage your pool. Test kits cannot differentiate below 6.8, so your pH may be much lower than that actually. You can use 20 Mule Team Borax (laundry aisle at Walmart) to raise it. It is added slowly to the skimmer while the pump is running, breaking up any clumps. Start with a half a box. After a few hours, retest and redose until you get it between 7.2-7.8. High chlorine levels will give false pH results, so the best thing for you to do, is to get the pH in range before you start shocking the pool.
One last comment --- a 2hp pump is HUGE for this size pool. Sometimes too large of a pump causes things to blow right through the filter instead of being trapped in the sand. I have a 24ft AG and I have a full-rated 1/2 hp inground pump on my pool and it is plenty big.
Come back with more questions and keep us posted of your progress!
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